Taubes-Guyenet debate. My analysis (V)

(Versión en español: hacer click aquí)

My notes on the fifth and last segment of the debate and my comments below them:

  • [GT 2h6m] The purpose of NuSI was to stop using these garbage poorly-designed studies, and design studies that asked the right questions. The pilot study was not randomized, and, therefore, you can’t infer causality.
  • [GT 2h7m] Sugar may be the something that you need to add to other carbohydrates to make them fattening. If you want to test this hypothesis, you have to do the experiments right.
  • [GT 2h8m] There is a new version of the Ludwig’s study being done. Whatever that study finds, Kevin Hall will probably look at it and find a reason to question it. This is how science works. There is counterevidence to everything. If there wasn’t, a journalist would not be required.
  • [Joe Rogan 2h9m] Why are sugary carbohydrates the most fattening?
  • [GT 2h9m] Stephan would say that they trigger food reward, I would say that they create a hormonal milieu in the body that overresponds to insulin. If you have a look in a textbook for what causes fat storage, insulin is the hormone that primarily regulates fat storage in your fat cells. Fructose is mostly metabolized in the liver and it may cause insulin resistance and, if it does, you overrespond to insulin.
  • [SG 2h10m] Sugar is the factor that makes us want to eat foods. It causes dopamine release in the brain and this sets our motivational levels to do some behaviors. Drugs act via dopamine.
  • [Joe Rogan 2h10m] But you’re saying that the same amount of carbohydrates, sugary carbohydrates versus vegetable carbohydrates, sugary carbohydrates are going to be more fattening.
  • [SG 2h10m] No, no, I didn’t say it was independently of calories. It is entirely dependent on calories. We have RCTs demonstrating this.
  • [Joe Rogan 2h11m] These RCTs, are they short-term?
  • SG 2h11m] Depends on how you define short-term. They are not lasting years and years.
  • [Joe Rogan 2h11m] Isn’t the issue long-term chronic effects?
  • [SG 2h11m] Possibly, but if you believe insulin is the cause, the effect of insulin on fat cells happens almost immediately. I am not aware of any mechanism that takes more than a few hours to occur. You shouldn’t have to wait months and months for this to occur.
  • [GT 2h11m] That doesn’t make any sense at all to me. He is kind of making this up as he goes along.
  • [SG 2h11m] Oh, Jesus!
  • [SG 2h14m] Insulin has effects on enzimes that cause fat cells to take up more fat and release less fat. That’s what that textbook talks about. That does not imply that insulin causes fat accumulation from day to day.
  • [SG 2h14m] When you eat a diet that is high in carbohydrates and low in fat, insulin goes up and your body restricts the fat from going out of fat cells, turns that down, not off, and then your body is burning carbs. If you eat a diet that is high in fat and low in carbohydrates, you secrete less insulin, those effects don’t occur on your fat cells, and that allows your body to burn the fat that you just ate. But at the end of the day, the amount of fat that you have on your body is the amount that you ate minus the amount that you burned. If you eat a low fat diet, you are not eating much and you are not burning much, but you’re in the same place as if you’re eating a lot of fat and burning a lot of fat. We know that this is true because varying the amount of carbohydrates makes no difference on RCTs. That’s how we know that what I just said is correct.
  • [GT 2h16m] One of the problems with modern nutritional science is that you do crappy studies, generate garbage, and then put together a lot of garbage and say we can find the truth in there. The answer is do better studies.
  • [GT 2h16m] The difference between fat ingested and fat expended has to be 10 kcal/d. No study was ever done that measured people ingesting 1500 kcal/d and expending 1490 kcal/d. For example, in the Kevin Hall study they didn’t measure ketones lost or energy in feces.
  • [Joe Rogan 2h18m] [He reads the effects of insulin in fat cells from a textbook]
  • [GT 2h20m] Keith Frayn, the author of the textbook explained to me for 20 minutes how insulin traps, determines, fatty acid trafficking accross the fat cell membrane, but when we talked about obesity he said it is because people eat too much. I told him he switched mechanisms: one mechanism for fat cells, a different mechanism for why people get fat. He said: “I never thought of that”. I asked him to come up with a hypothesis for obesity from the fat cell perspective, and he said “I can’t put energy balance aside”.
  • [GT 2h23m] All these people, including Stephan, they are so locked into this thinking, they can’t get away from it. Even when he says he is using a lot of studies, I can guarantee that if we have a look at all these studies, they assumed energy balance was the cause and they started with the wrong hypothesis.
  • [SG 2h24m] Gary, I preordered your book. I was so persuaded 10 years ago that I ate a low-carb diet for 6 months. I was fully convinced by your perspective. The thing that caused me to go away from that perspective is when I started to actually investigate evidence on my own. And evidence didn’t line up with what you were saying in your book. Your arguments in GCBC rely on historical narrative and speculation. And others who have looked at the same historical events have come to different conclusions than you have. And that includes me.
  • [SG 2h26m] I am post-Taubes. [He laughs]
  • [GT 2h27m] There are different ways to look at the evidence. Maybe you eat less on a low-carb diet because your insulin is low.
  • [SG 2h27m] Can you give me evidence that that is the reason?
  • [GT 2h27m] No.
  • [SG 2h28m] When you feed people, whether it is overfeeding or underfeeding, the carb to fat ratio of the diet makes almost no difference.
  • [GT 2h29m] In overfeeding experiments, they could make people overeat 10000 kcal/d of carbohydrate calories, but they couldn’t make people overeat more than 1000 kcal of fat. Is it because the carbs are doing something in the brain or is it that the carbs are doing something in the body? There are always two ways to look at it.
  • [GT 2h31m] Even if I am wrong, I assume that telling people to eat less sugar is a good thing.
  • [SG 2h32m] Not entirely, because you are telling people that only carbohydrate matters…
  • [GT 2h32m] I am not.
  • [SG 2h32m] You are telling people that caloric intake, and dietary fat intake and physical activity do not influence body fatness and are not important.
  • [GT 2h32m] I refuse to believe that someone who is obese got that way because they are sedentary.
  • [SG 2h32m] There is harm in what you’re saying because you are saying that other important factors are irrelevant.
  • [GT 2h32m] No. No. No. What I am saying about calories is that it is the wrong way to think about it. They are a way to measure the amount of food. You could use grams.
  • [GT 2h33m] [He reads a text]
  • [GT 2h34m] One of my problems with the whole overeating hypothesis is that it’s tautological. You don’t know if someone is overeating unless they’re fat, right?
  • [SG 2h34m] Incorrect. You can measure his calorie intake and you can know. I don’t know what you’re talking about.
  • [GT 2h34m] How do you know if I overeat?
  • [SG 2h35m] It depends on how you define that. But looking at your body composition I can tell you whether you’re overeating relatively to a lean person.
  • [GT 2h35m] Because I have excess body fat.
  • [SG 2h35m] Correct.
  • [GT 2h35m] Without knowing if I have body fat you cannot know if I am overeating, right?
  • [SG 2h35m] Uhhhh
  • [GT 2h35m] Doesn’t it strike you as circular?
  • [SG 2h35m] Theres is nothing circular about it. If you take somebody and increase their food intake they gain body fat. There is nothing circular about it. And if you reduce their calorie intake, they lose body fat. It’s so simple and direct.

Guyenet’s beliefs are contrary to scientific evidence

We can no longer doubt that Guyenet defends that calories determine if we gain body fat or we don’t:

  • [Joe Rogan 2h10m] But you’re saying that the same amount of carbohydrates, sugary carbohydrates versus vegetable carbohydrates, sugary carbohydrates are going to be more fattening.
  • [SG 2h10m] No, no, I did not say it was independently of calories. It is entirely dependent on calories. We have RCTs demonstrating this.

And, as he says in that fragment and he repeats later, he does not say that it is because of the laws of thermodynamics: he says that scientific experiments are what supports his claims. This is very important:

[SG 2h14m] We know that this is true because varying the amount of carbohydrates makes no difference on RCTs. That’s how we know that what I just said is correct.

Why is this relevant? Because Guyenet is unable to defend his pseudoscience arguing that it derives from the First Law of Thermodynamics. He says that what proves that he is right in his beliefs is that experimental evidence proves him right. Or, in other words, the real value of his ideology is conditioned by the lucidity of his interpretations of scientific evidence. And the scientific evidence he provides is:

  1. Very short-term experiments for which Guyenet ignores their duration and also ignores that there are differences between diets. His conclusion that there are no differences is just a lie.
  2. Absolute lack of long-term controlled experiments.

I do not say that it is his fault not to provide long-term evidence, but that the fact that it is not his fault doesn’t make relevant the short-term evidence he provides. In addition to that, he makes a simplistic and biased interpretation of those studies.

Morover, Guyenet is ignoring the abundant scientific evidence that shows that body fat accumulation is not determined by calories. The scientific evidence that refutes his hypothesis is endless. Two years ago I created a list with all the blog entries that presented scientific experiments that demonstrated this. The list includes almost 100 articles: see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see, see. And it’s been more than two years since I created the list, so we can find much more scientific articles in this blog that show the same results.

Why can’t Guyenet see the scientific evidence that refutes his hypothesis and instead of that he holds on to short-term experiments that do not show what he says? Faith is not scientific evidence. Although the controlled experiments that can be carried out in humans are short-term, that does not make those studies relevant nor does it allow us to make what happens in the long term up. The fact that Kevin Hall deduces from those short-term studies that for any practical purpose the composition of the diet does not matter is simply bad science. My bolds:

In other words, for all practical purposes “a calorie is a calorie” when it comes to body fat and energy expenditure differences between controlled isocaloric diets varying in the ratio of carbohydrate to fat. Kevin Hall, PhD

The effects of insulin are immediate

Another facepalm moment thanks to Guyenet. But this is typical Guyenet. Are there no long-term changes in the action of insulin? Is there a physiological process called “insulin resistance” that can make the effects of insulin change in the long term? Is Guyenet really saying what he is saying?

Another example. As we have seen in this blog (see), in people who have lost weight, the effect of insulin on LPL can be clearly altered, and the same happens with lipolysis, something that may be explained by the size of the adipocytes (see)

The composition of the diet is not relevant

[SG 2h14m] When you eat a diet that is high in carbohydrates and low in fat, insulin goes up and your body restricts the fat from going out of fat cells, turns that down, not off, and then your body is burning carbs. If you eat a diet that is high in fat and low in carbohydrates, you secrete less insulin, those effects do not occur on your fat cells, and that allows your body to burn the fat that you just ate. But at the end of the day, the amount of fat that you have on your body is the amount that you have minus the amount that you burned. If you eat a low fat diet, you are not eating much and you are not burning much, but you’re in the same place as if you’re eating a lot of fat and burning a lot of fat. We know that this is true because varying the amount of carbohydrates makes no difference on RCT. That’s how we know that what I just said is correct.

When insulin is high it is not necessary to get fat from the adipose tissue because we already have dietary carbohydrates to burn. OK. When insulin levesl are low (a diet high in fat and low in carbohydrates) Guyenet says that that does not happen, that is, low insulin does let the fat out of the fat tissue. But that is not really necessary because we already have dietary fat to burn, right? Does that really make sense in his narrative? I think he is right, but his message is inconsistent. You’d say he’s got into a muddle.

In any case, the interesting thing about this narrative is that, as he recognizes at the end of the quote above, it doesn’t have to be that way. He justifies his beliefs by saying that, in his opinion, this is what scientific experiments say.

That’s how we know that what I just said is correct.

Well, since well-controlled scientific experiments do not say that, neither those that exist, which are short-term, nor those that don’t exist, which would be long-term, the story that he is telling is worthless. What happened with the First Law of Thermodynamics as a justification for his pseudoscience?

The insulin hypothesis is not consistent with basic thermodynamics. Stephan Guyenet, PhD

Oh, yes, it is consistent. And Guyenet has not dared to say the opposite to Taubes.

Guyenet is in a post-Taubes phase

Guyenet claims that he has put behind him his belief in Taubes’ hypothesis. This is such a good argument because a long time ago Taubes also believed that Guyenet’s pseudoscience was correct. Taubes can also say that he is in a post-Guyenet phase. Why is Guyenet laughing?

We store the difference between what we eat and what we burn

[SG 2h14m] at the end of the day, the amount of fat that you have on your body is the amount that you ate minus the amount that you burned

Is there something wrong with Guyenet’s claim? In a summarized form, let’s say that expressing it like that is the first step for the deception to happen, which is to make people believe that the difference between our energy intake and our energy expenditure determines how much body fat we accumulate. Morover, notice that Guyenet’s expression only mentions two terms from the energy balance equation: by isolating those terms he is making them the relevant terms.

We could also say that every day we store as body fat what is stored in our adipose tissue. There is no information in this claim, in exactly the same way as there is no information in Guyenet’s sentence, but at least we focus our attention on the main character involved in fat accumulation. I refer to this entry of the blog for detailed comments on where the problem with Guyenet’s sentence lies.

Taubes’ ideas harm

That’s what Guyenet says. Or perhaps the ideas that have harmed the health of the population in the last century are those defended by Guyenet. There is zero self-criticism in Guyenet. He never questions his pseudoscience. But when someone explains the errors that are the foundation of his beliefs, instead of recognizing the grave error that is his ideology, he says that the critic damages the health of the population. No, it is not the critic: it is Guyenet who harms.

The circular thinking of “overeating”

The final part of the debate is very interesting. “Good Calories Bad Calories”, the book by Taubes, was published in 2007, i.e. 11 years ago. Guyenet has had plenty of time to understand the tautology on which his pseudoscience is based.

I do not know what you’re talking about.

Moreover, Guyenet has changed his message from the one he had a few years ago (see). As we have seen, he doesn’t dare to justify his beliefs by mentioning the First Law of Thermodynamics. Has he rectified his error without understanding Taubes’ explanations about tautologies and circular thinking? Does he really not know what Taubes is talking about? I don’t believe him. I can’t believe him.

About circular arguments, Taubes is absolutely right, and his explanations are impeccable. As he also explained in this debate, in the energy balance pseudoscience overeating is another way of saying body fat accumulation. In that paradigm, if you are not accumulating body fat, you are not overeating. And if you accumulate body fat, then you are overeating. Guyenet even acknowledges that to know if you have overeaten he would check your fat mass. In the energetic paradigm, a tautology is incomprehensibly mistaken for an explanation. The circular thinking is evident.

And the final explanation from Guyenet is very enlightening: he says that if you increase your intake or you reduce it, that makes you gain or lose body fat. It is the single cause fallacy, as I have already commented in this analysis. And we must take into account under what conditions it has been verified what Guyenet says: in the short term and with huge variations in the caloric intake. Or, in other words, it has never been proven in the circumstances in which the energy balance pseudoscience proposes that fattening happens in real life, which are long-term and with a very small increase in the caloric intake. Nor, as Taubes correctly points out, have alternative options been considered in the long term. What Guyenet claims that is “simple and direct”, is an undoubtedly erroneous belief born from fallacies and paralogisms. And Taubes explains this perfectly.

NOTE: I insist that the terminology of the energy balance paradigm can be used only if that pseudoscience is first proved correct. Caloric excess, caloric deficit, overeating, etc. are terms that belong to this paradigm. Before using these terms, it must be justified that they can be used.

Go to the conclusions
Go to the fifth part
Go to the fourth part
Go to the third part
Go to the second part
Go to the first part

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Debate Taubes-Guyenet. Mi análisis (V)

(English version: click here)

Mis notas sobre el último segmento del debate y tras ellas mis comentarios:

  • [GT 2h6m] El propósito de NuSI era dejar de usar estos estudios-basura mal diseñados, y diseñar estudios que hicieran las preguntas correctas. El estudio piloto no fue aleatorizado y, por lo tanto, no se puede inferir una causalidad.
  • [GT 2h7m] El azúcar puede ser algo que necesitas agregar a otros carbohidratos para hacerlos engordantes. Si quieres testear esta hipótesis, tienes que hacer los experimentos correctamente.
  • [GT 2h8m] Se está realizando una nueva versión del estudio de Ludwig. Independientemente de lo que encuentre ese estudio, Kevin Hall probablemente lo mirará y encontrará una razón para cuestionarlo. Así es cómo funciona la ciencia. Hay contra-evidencia para todo. Si no fuera así, no se haría falta un periodista.
  • [Joe Rogan 2h9m] ¿Por qué los carbohidratos azucarados son los que más engordan?
  • [GT 2h9m] Stephan diría que activan la recompensa de alimentos, yo diría que crean un medio hormonal en el cuerpo que responde en exceso a la insulina. Si busca en un libro de texto qué causa el almacenamiento de grasa, la insulina es la hormona que principalmente regula el almacenamiento de grasa en las células grasas. La fructosa se metaboliza principalmente en el hígado y puede causar resistencia a la insulina y, si lo hace, usted responde en exceso a la insulina.
  • [SG 2h10m] El azúcar es el factor que nos hace querer comer alimentos. Provoca la liberación de dopamina en el cerebro y esto establece nuestros niveles de motivación para realizar algunas conductas. Las drogas actúan a través de la dopamina.
  • [Joe Rogan 2h10m] Pero estás diciendo que con la misma cantidad de carbohidratos, carbohidratos azucarados versus carbohidratos vegetales, los carbohidratos azucarados engordarán más.
  • [SG 2h10m] No, no, no dije que fuera independientemente de las calorías. Es totalmente dependiente de las calorías. Tenemos RCTs que demuestran esto.
  • [Joe Rogan 2h11m] Estos RCTs, ¿son a corto plazo?
  • [SG 2h11m] Depende de cómo se defina a corto plazo. No duran años y años.
  • [Joe Rogan 2h11m] ¿No es el problema los efectos crónicos a largo plazo?
  • [SG 2h11m] Posiblemente, pero si crees que la insulina es la causa, el efecto de la insulina en las células grasas ocurre casi de inmediato. No tengo conocimiento de ningún mecanismo que tarde más de unas pocas horas en producirse. No debería tener que esperar meses y meses para que esto ocurra.
  • [GT 2h11m] Eso no tiene ningún sentido para mí. Se lo inventa sobre la marcha.
  • [SG 2h11m] ¡Oh, Jesús!
  • [SG 2h14m] La insulina tiene efectos sobre las enzimas que hacen que las células grasas cojan más grasa y liberen menos grasa. De eso trata el libro de texto. Eso no significa que la insulina cause la acumulación de grasa de día a día.
  • [SG 2h14m] Cuando consumes una dieta alta en carbohidratos y baja en grasas, la insulina aumenta y tu cuerpo restringe la salida de grasa de las células grasas, lo reduce, no lo elimina y así tu cuerpo quema carbohidratos. Si consume una dieta alta en grasas y baja en carbohidratos, secreta menos insulina, esos efectos no se producen en las células grasas y eso le permite a su cuerpo quemar la grasa que acaba de ingerir. Pero al final del día, la cantidad de grasa que queda en tu cuerpo es la cantidad ingerida menos la cantidad quemada. Si comes una dieta baja en grasas, no estás comiendo mucha y no estás quemando mucha, pero obtienes el mismo resultado que si estuvieras comiendo mucha grasa y quemando mucha grasa. Sabemos que esto es cierto porque variar la cantidad de carbohidratos no produce ninguna diferencia en los RCTs. Así es como sabemos que lo que acabo de decir es correcto.
  • [GT 2h16m] Uno de los problemas con la ciencia nutricional moderna es que haces estudios de mierda, generas basura y luego juntas mucha basura y dices que podemos encontrar la verdad ahí. La respuesta es hacer mejores estudios.
  • [GT 2h16m] La diferencia entre la grasa ingerida y la grasa gastada debe ser de 10 kcal/d. No se ha hecho ningún estudio que midiera a las personas una ingesta de 1500 kcal/d y un gasto de 1490 kcal/d. Por ejemplo, en el estudio de Kevin Hall no midieron las cetonas perdidas o la energía en las heces.
  • [Joe Rogan 2h18m] [Lee los efectos de la insulina en las células de grasa de un libro de texto] 
  • [GT 2h20m] Keith Frayn, el autor del libro de texto, me explicó durante 20 minutos cómo la insulina atrapa —determina el tráfico de— ácidos grasos a través de la membrana de las células grasas, pero cuando hablamos de obesidad, dijo que es porque la gente come demasiado. Le dije que me había cambiado los mecanismos: me daba un mecanismo para los adipocitos y un mecanismo diferente por el cuál las personas engordan. Dijo: “Nunca pensé en eso”. Le pedí que formulara una hipótesis para la obesidad desde la perspectiva de las células grasas y dijo: “No puedo dejar de lado el equilibrio energético”.
  • [GT 2h23m] Todas estas personas, incluido Stephan, están tan atrapados en este pensamiento que no pueden escapar de él. Incluso cuando dice que está utilizando muchos estudios, puedo garantizar que si analizamos todos estos estudios, todos asumieron que la causa era el equilibrio de energía y comenzaron con la hipótesis incorrecta.
  • [SG 2h24m] Gary, preordené tu libro. Estaba tan convencido hace 10 años que seguí una dieta baja en carbohidratos durante 6 meses. Estaba completamente convencido por tu perspectiva. Lo que me hizo alejarme de esa perspectiva fue cuando comencé a investigar las pruebas por mi cuenta. Y la evidencia no se alineó con lo que estabas diciendo en tu libro. Tus argumentos en GCBC se basan en la narrativa histórica y la especulación. Y otros que han analizado los mismos acontecimientos históricos han llegado a conclusiones diferentes a las tuyas. Y eso me incluye.
  • [SG 2h26m] Soy post-Taubes. [Ríe]
  • [GT 2h27m] Hay diferentes maneras de ver la evidencia. Puede ser que coma menos en una dieta baja en carbohidratos porque su insulina es baja.
  • [SG 2h27m] ¿Puedes darme evidencia de que ésa es la razón?
  • [GT 2h27m] No.
  • [SG 2h28m] Cuando se alimenta a las personas, ya sea sobrealimentación o subalimentación, la proporción de carbohidratos y grasas de la dieta casi no tiene ninguna relevancia.
  • [GT 2h29m] En experimentos de sobrealimentación, podrían hacer que las personas comieran en exceso 10000 kcal/d de carbohidratos, pero no podían hacer que las personas comieran en exceso más de 1000 kcal de grasa. ¿Es porque los carbohidratos están haciendo algo en el cerebro o es porque los carbohidratos están haciendo algo en el cuerpo? Siempre hay dos formas de verlo.
  • [GT 2h31m] Incluso si estoy equivocado, asumo que decirle a la gente que coma menos azúcar es algo bueno.
  • [SG 2h32m] No del todo, porque le estás diciendo a la gente que solo los carbohidratos son importantes …
  • [GT 2h32m] No lo hago.
  • [SG 2h32m] Le estás diciendo a la gente que la ingesta calórica y la ingesta de grasas en la dieta y la actividad física no influyen en la grasa corporal y no son importantes.
  • [GT 2h32m] Me niego a creer que algunos de los que son obesos llegaron a serlo porque son sedentarios.
  • [SG 2h32m] Hay daño en lo que estás diciendo porque estás diciendo que otros factores importantes son irrelevantes.
  • [GT 2h32m] No. No. No. Lo que estoy diciendo acerca de las calorías es que es una manera incorrecta de pensar en este asunto. Son una forma de medir la cantidad de comida. Podrías usar gramos.
  • [GT 2h33m] [Lee un texto]
  • [GT 2h34m] Uno de mis problemas con toda la hipótesis de comer en exceso es que es tautológico. No sabes si alguien está comiendo en exceso a menos que haya engordado, ¿verdad?
  • [SG 2h34m] Incorrecto. Puedes medir su ingesta de calorías y puedes saberlo. No sé de qué estás hablando.
  • [GT 2h34m] ¿Cómo sabes si comí en exceso?
  • [SG 2h35m] Depende de cómo lo definas. Pero observando la composición de tu cuerpo, puedo decirte si estás comiendo en exceso con respecto a una persona magra.
  • [GT 2h35m] Porque tengo exceso de grasa corporal.
  • [SG 2h35m] Correcto.
  • [GT 2h35m] Sin saber si tengo grasa corporal, no puedes saber si estoy comiendo en exceso, ¿verdad?
  • [SG 2h35m] Ummm
  • [GT 2h35m] ¿No te parece circular?
  • [SG 2h35m] No hay nada circular en esto. Si coges a alguien y aumentas su ingesta de alimentos, ganan grasa corporal, no hay nada circular en ello. Y si les reduces la ingesta de calorías, pierden grasa corporal. ¡Es tan simple y directo!

Las creencias de Guyenet son contrarias a la evidencia científica

Sobre si Guyenet defiende que todo es cuestión de calorías, más claro no puede ser que sí lo hace:

  • [Joe Rogan 2h10m] Pero estás diciendo que con la misma cantidad de carbohidratos, carbohidratos azucarados versus carbohidratos vegetales, los carbohidratos azucarados engordarán más.
  • [SG 2h10m] No, no, no dije que fuera independientemente de las calorías. Es totalmente dependiente de las calorías. Tenemos RCTs que demuestran esto.

Y, como dice en ese fragmento y repite más tarde, no dice que sea por las leyes de la termodinámica : dice que es lo que se deduce de los experimentos científicos. Esto es importantísimo:

  • [SG 2h14m] Sabemos que esto es cierto porque variar la cantidad de carbohidratos no produce ninguna diferencia en los RCTs. Así es como sabemos que lo que acabo de decir es correcto.

¿Por qué es importante? Pues porque Guyenet es incapaz de defender su pseudociencia argumentando que deriva de la Primera Ley de la Termodinámica: dice que lo que demuestra que él tiene razón en sus creencias es que se comprueba que es así en los experimentos científicos. O, en otras palabras, la validez de su ideología está condicionada por la lucidez de su interpretación de la evidencia científica. Y la evidencia científica que aporta es:

  1. Experimentos a cortísimo plazo para los que Guyenet ignora la duración de los experimentos e ignora que sí se encuentran diferencias entre dietas. Su conclusión de que no hay diferencias es simplemente mentira.
  2. Carencia de experimentos controlados a largo plazo.

No digo que sea culpa suya no tener evidencia de calidad a largo plazo, pero que no sea culpa suya no hace buena la evidencia a corto plazo que aporta, para la que, además, hace una interpretación simplista y sesgada.

Y Guyenet está ignorando la abundantísima evidencia científica que demuestra que la acumulación de grasa corporal no viene determinada por las calorías. La evidencia científica que demuestra incorrecta su hipótesis es interminable. Hace dos años creé un listado con todas las entradas del blog que presentaban experimentos cientificos que demostraban esto. Ésta es la lista de esos casi 100 artículos del blog: ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver, ver. Y han pasado más de dos años, en los que hemos visto más artículos que demuestran lo mismo.

¿Por qué Guyenet no ve la evidencia científica que refuta su hipótesis y se agarra a experimentos a corto plazo que no demuestran lo que él dice? Su fe no es evidencia científica. Aunque los experimentos controlados que se pueden hacer en humanos son a corto plazo, eso no los hace relevantes ni le permite inventarse lo que sucede a largo plazo. El hecho de que Kevin Hall, a partir de esos experimentos a corto plazo, diga que para cualquier propósito práctico la composición de la dieta no importa es sencillamente mala ciencia. Mis negritas:

para cualquier propósito práctico “una caloría es una caloría” cuando se trata de diferencias en grasa corporal y gasto energético entre dietas isocalóricas controladas que se diferencian en el ratio de carbohidratos a grasa. Kevin Hall, PhD

Los efectos de la insulina son inmediatos

El argumento de Guyenet es para echarse las manos a la cabeza. Pero con Guyenet estamos ya curados de espanto. ¿No hay cambios a largo plazo en la acción de la insulina? ¿No hay una cosa, por ejemplo, llamada “resistencia a la insulina” que puede hacer que los efectos de la insulina cambien a largo plazo? ¿De verdad Guyenet está diciendo lo que está diciendo?

Otro ejemplo. Como hemos visto en el blog (ver), en personas que han bajado de peso, la acción de la insulina en la LPL puede estar claramente alterada, y lo mismo pasa con la lipólisis, algo que quizá se explique por el tamaño de los adipocitos (ver).

La composición de la dieta no es relevante

[SG 2h14m] When you eat a diet that is high in carbohydrates and low in fat, insulin goes up and your body restricts the fat from going out of fat cells, turns that down, not off, and then your body is burning carbs. If you eat a diet that is high in fat and low in carbohydrates, you secrete less insulin, those effects don’t occur on your fat cells, and that allows your body to burn the fat that you just ate. But at the end of the day, the amount of fat that you have on your body is the amount that you ate minus the amount that you burned. If you eat a low fat diet, you are not eating much and you are not burning much, but you’re in the same place as if you’re eating a lot of fat and burning a lot of fat. We know that this is true because varying the amount of carbohydrates makes no difference on RCT. That’s how we know that what I just said is correct.

Con la insulina alta, no es necesario sacar grasa del tejido adiposo porque tenemos carbohidratos que quemar. Vale. Con la insulina baja (dieta alta en grasa y baja en carbohidratos) dice que eso no sucede, es decir, la insulina baja sí deja que la grasa salga del tejido graso, siendo que en realidad no es necesario pues ya está la grasa dietética para ser quemada. ¿De verdad tiene eso sentido en su narrativa? Yo lo veo cierto, pero incoherente en su mensaje. Se diría que se ha liado explicándolo.

En cualquier caso, lo interesante de esta narrativa es que, como él reconoce al final de la cita, no tiene por qué ser así. Lo justifica diciendo que lo cree así porque, en su opinión, es lo que dicen los experimentos científicos.

That’s how we know that what I just said is correct.

Vale, pues como los experimentos científicos bien controlados no dicen eso, ni los que existen, a corto plazo, ni los que no existen, a largo plazo, esta historieta que nos ha contado no vale nada. ¿Dónde quedó la Primera Ley de la Termodinámica como justificación de su pseudociencia?

the insulin hypothesis is not consistent with basic thermodynamics. Stephan Guyenet, PhD

Oh, sí, sí que es consistente. Y Guyenet no se ha atrevido a decir lo contrario con Taubes delante.

Guyenet está en una fase post-Taubes

Guyenet presume de estar en una fase más avanzada que creer en la hipótesis de Taubes. Menudo argumento: también Taubes creyó en su día correcta la pseudociencia de Guyenet, y podría, por tanto, presumir de estar en una fase post-Guyenet. ¿Qué argumento es éste? ¿De qué se ríe Guyenet?

Engordamos la diferencia entre lo que ingerimos y lo que quemamos

[SG 2h14m] al final del día, la cantidad de grasa que queda en tu cuerpo es la cantidad ingerida menos la cantidad quemada.

¿Es que no es correcto lo que afirma Guyenet? Digamos que expresarlo así es el primer paso para consumar la trampa, que es hacer creer que ingesta energética y gasto energético determinan cuánta grasa acumulamos. Nótese como en la expresión de Guyenet sólo hay dos términos de la ecuación del balance de energía: aislando esos términos los está convirtiendo en los relevantes.

También podríamos decir que cada día engordamos lo que es almacenado en el tejido adiposo. Esta afirmación no aporta nada, igual que no la aporta la frase de Guyenet, pero al menos centramos la atención en el tejido protagonista en la acumulación de grasa corporal. Remito a esta entrada del blog para un comentario más detallado de dónde está el problema con la frase de Guyenet.

Las ideas de Taubes hacen daño

Eso dice Guyenet. O a lo mejor son las ideas de Guyenet las que durante el último siglo han estado dañando la salud de la población. Hay cero autocrítica en Guyenet. Su pseudociencia no la cuestiona. Pero cuando se ponen sobre la mesa los errores en su pseudociencia, este tipo en lugar de reconocer el gravísimo error que es su ideología, reacciona diciendo que el crítico daña la salud de la población. No, no es el crítico: es Guyenet el que hace daño.

El pensamiento circular del “sobreconsumo”

La parte final del debate es muy interesante. “Good Calories Bad Calories”, el libro de Taubes, se publicó en el 2007, hace ya 11 años. Tiempo ha tenido Guyenet para entender la tautología en la que se basa su pseudociencia.

I don’t know what you’re talking about.

Es más, Guyenet ha cambiado su mensaje respecto del que sostenía hace unos años (ver). Como hemos visto, no se ha atrevido a intentar justificar sus creencias mencionando la Primera Ley de la Termodinámica. ¿Ha rectificado su error pero lo ha hecho sin entender las explicaciones de Taubes sobre la tautología y el pensamiento circular? ¿De verdad no sabe de qué habla Taubes? Yo no le creo. No puedo creerle.

En el asunto del pensamiento circular, Taubes tiene toda la razón, y lo explica perfectamente. También en el debate lo ha explicado: overeating, que podemos traducir como sobreconsumo o comer de más, es equivalente en la pseudociencia del balance energético a acumular grasa corporal: son dos formas de decir lo mismo. En ese paradigma, si no estás acumulando grasa corporal, no comes “de más”. Y si acumulas grasa corporal, entonces comes “de más”. Si es que hasta Guyenet dice que para saber si has comido “de más” lo que haría es comprobar si tienes grasa corporal. En el paradigma energético, la tautología es convertida incomprensiblemente en explicación. El pensamiento circular es evidente.

Y la explicación final de Guyenet me parece muy ilustrativa: dice que si aumentas la ingesta o la reduces, eso se traduce en más o menos grasa corporal. Es la falacia de causa única, como ya he comentado. Y hay que plantearse en qué condiciones se ha comprobado lo que Guyenet dice: a corto plazo y con variaciones de ingesta enormes. O, en otras palabras, no se ha comprobado en las circunstancias en las que la pseudociencia del balance energético propone que sucede en la vida real el engorde, que es a largo plazo y con una variación mínima en la ingesta. Ni, como bien apunta Taubes, se han examinado las opciones alternativas a largo plazo. Lo que Guyenet dice que es sencillo y directo, es simplemente una creencia errónea nacida de falacias y paralogismos. Y Taubes lo explica perfectamente.

NOTA: Insisto en que la terminología del balance energético se puede emplear sólo si esa pseudociencia se demuestra primero correcta. Exceso calórico, déficit calórico, sobreconsumo, etc. son términos que pertenecen a ese paradigma. Antes de emplear esos términos, hay que justificar que pueden ser usados.

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Taubes-Guyenet debate. My analysis (IV)

(Versión en español: hacer click aquí)

My notes on the fourth segment of the debate (next-to-last) and my comments below them:

  • [GT 1h33m] The sugar hypothesis: you add something about a western diet/lifestyle to populations, you get explotions of obesity and diabetes. My hypothesis is that sugar is the something that has to be added. Maybe it is sugary beverages.
  • [SG 1h34m] It’s always possible to tell stories to salvage your hypothesis, but that does not necessarily make the story correct. We don’t have any evidence to support what Gary just said. Quote from Christopher Hitchens: “That which is asserted without evidence, can be dismissed without evidence”. And that’s the way I feel about this particular story.
  • [SG 1h35m] I am going to talk about three different cultures that eat a lot of sugar and don’t have obesity. The Hadza in Tanzania eat a lot of honey. 15% of their calorie intake comes from honey. This is as much as americans eat and they eat fruit on top of this. The pygmies in the Congo also eat a lot of honey. Up to 80% from calories can come from honey during the rainy season. And they are lean.
  • [SG 1h38m] If you eat a lot of sugar but everything else is in place, the sugar is not enough to make them fat. I am not saying it doesn’t contribute, I think sugar does contribute, but it is not singlehandedly responsible as Gary has argued. The Kuna of Panama is the 3d culture. They eat white sugar.
  • [Joe Rogan 1h39m] In non westernized-civilizations you burn off so many calories…
  • [SG 1h40m] I 100% agree with you.
  • [Joe Rogan 1h40m] The thing about burning off the calories is that in westernized lifestyles you are just existing, they are doing nothing to burn the shit off. I think what Gary is getting at is that if you have this lifestyle and then with that lifestyle consume sugar you are going to get fat. I don’t think you can compare that to athletes and I don’t think you can compare that to hunther-gatherers. I remember being working out 4h/day and eating everything I was in the mood (soda, cookies, etc.), and not gaining any weight other than muscle.
  • [SG 1h42m] I agree that it is not as simple as sugar, but Gary argues that sugar is the primary cause of obesity and that physical activity does not matter, calorie intake does not matter.
  • [GT 1h42m] When we talk about the cause of obesity, I don’t believe obese people become obese because they are sedentary.
  • [Joe Rogan 1h42m] Don’t you think that an athlete has a high sugar demand and will burn that off?
  • [GT 1h42m] Absolutely.
  • [GT 1h43m] Can I go back to the Kuna? Stephan calls my stories, stories, which they are, but he calls his “evidence”. About the Kuna [he reads a text from an e-mail exchange with Guyenet] they eat a low amount of sugar (32 pounds of sugar per year) and we don’t know how that amount has changed over the years. [Guyenet laughs out loudly while Taubes speaks] I also don’t believe the data from the urbanized Kuna, who apparently drink only 3 8-oz soda per week, and they consumed more sugar back where they used to live.
  • [GT 1h45m] Stephan is constantly citing studies which only speak about one hypothesis, like the overfeeding studies, or that are poorly constructed and poorly done. About the Hadza, I already told him that I don’t think it is a refutation of my hypothesis, since my hypothesis is that when you add sugar to the diet of any population you get obesity. May be the Hadza have been eating honey for 1000s of years. May be when they inmigrated to this area they had obesity then. I don’t think finding a hunter-gatherer population that eats honey and doesn’t have obesity is a refutation, Stephan does.
  • [GT 1h47m] My non-for-profit funded a study with 40 kids that had NFLD.They could eat fruit, as much as they wanted, but no added sugar and no sugary beverages. The fatty-liver disease resolved. We can’t talk about the mechanism. May be it was the weight loss.
  • [GT 1h48m] About the metaanálisis from Hall, it is putting together all the junk-science that has been done in the last 50 years, while ignoring any quality of the studies. And they did a poor job. In one study I checked, they even confused a 400 kJ decrease in energy expenditure with a 400 kcal decrease [N.T. 400kJ=95kcal].
  • [GT 1h49m] You have to do the right studies if you want to get the right answer.
  • [GT 1h50m] Stephan openly rejected this study that NuSi funded with 12 million dollars. There are basically 3 preople out there that are convinced that everything people like me are saying is wrong.  They keep coming over and over again. Kevin Hall claims that he has refuted the carbohydrate-insulin model. When his study comes out supporting it, he works to find out why the study is wrong. We all do the same thing. The goal is ultimately to do the right study, because we have to remember what is on the line here.
  • [GT 1h51m] For decades people have thought as Stephan does, and there is an alternative hypothesis and we have to find if it is true because people are dying out there.
  • [SG 1h51m]  This alternative explanation has been investigated extensively, included studies that were funded by his own organization, NuSi. 2 out of the 3 studies were a clear refutation of his hypothesis. There is a remarkable correlation between studies undermining your beliefs and you thinking those studies are garbage. [Guyenet smiles]
  • [SG 1h52m] About the Hill and Peters studies, if you can’t actually find specific problems with the studies, you can’t just dismissed them.
  • [GT 1h53m] I gave you a problem with the study: it was designed based on the assumption it was supposed to test.
  • [SG 1h52m] Ok, it wasn’t designed how Gary wanted it to be designed.
  • [SG 1h53m] The Kuna. The primary basis for Gary’s book is that when sugar comes into this cultures they become fat. I am pointing out 3 cultures that eat high levels of sugar and are not fat. In reference [22] we can see that in the Cuban economic crisis the intake of sugar went up, 28% of caloric intake, double what Americans eat. Their calorie intake went down and they had to walk a lot because of the lack of gasoline. If Gary is right and calories don’t matter, only refined carbohydrates and sugar, obesity should have gone through the roof. The prevalence of obesity declined by half: from 14% to 7%. The rate of underweight increased only slightly. As soon as they went back to their original diet, obesity went up.
  • [GT 1h57m] I would have to read the study to figure out what the problem is.
  • [Joe Rogan 1h57m] What about the NuSi studies?
  • [GT 1h57m] Well, this is a game people play. My issue with Stephan is that he speaks as if though he knows, with this authority.
  • [SG 1h58m] The 2 first studies refuted Gary’s hypothesis. Gary is about the only person who thinks they did not refute his beliefs. The scientific community is pretty unanimous.
  • [GT 1h59m] The first study was a pilot study that depends on what you look at, you can think it refutes a belief. Kevin Hall tends to believe that obesity is an energy balance problem, David Ludwig and his colleagues tend to believe what I believe. If you believe Kevin interpreted correctly his study (the one funded by NuSi), then it is not supportive of carbohydrates being responsible of driving insulin and insulin being driving fat accumulation. The David Ludwig’s study reported the opposite. David has critisized Kevin’s study and Kevin’s has critisized David’s study. The middle study was a free-living study done by Christopher Gardner. The low-carb diet was not a meaningful low-carb diet and they told both groups not to eat sugars and refined grains, which are by my hypothesis the most fattening carbohydrates. They tested two diets and neither of them had sugar nor white bread. It was a poorly done study, it didn’t answer the question.
  • [SG 2h3m] Caloric deficit was self reported, so it is not actually accurate.
  • [SG 2h4m] There was a 2-fold difference in carbohydrate intake.
  • [GT 2h4m] If you believe the food frequency questionares that you just said we don’t know whether can be believed.
  • [SG 2h4m] I agree with you that refined carbohydrates and sugar are the most fattening types of carbohydrates.
  • [Joe Rogan 2h5m] OMG, we can do an agreement?
  • [GT 2h5m] The question is why. Is it because people eat too much of them?
  • [SG 2h5m] If you believe Gary’s hypothesis, since any type of carbohydrate increases insulin levels more than fat does, if that matters for fat loss, these groups had a 2-fold difference in carbohydrate intake, even though it was predominantly healthy carbs. You should have seen something, not the same amount of weight loss in both groups.
  • [Joe Rogan 2h5m] But they are not high in sugar, right? Your argument has been always about sugar, right?
  • [GT 2h5m] Stephan is right: I defend my hypothesis. He does the same. We all do it. And every study ever done has plenty of reasons not to believe it. This is why independent replications is something you always want.

The ad populum fallacy

[SG 1h58m] The 2 first studies refuted Gary’s hypothesis. Gary is about the only person who thinks they did not refute his beliefs. The scientific community is pretty unanimous.

The ad populum fallacy is the appeal to the popularity of an opinion as a reason to accept it. The number of people who believe a claim is true is irrelevant in relation to whether it is correct or not. Taubes is aware that his ideas go against the prevailing opinions.

Guna, Cuba and Hadza

I think it would be a mistake to ignore the examples of the Guna, Hadza or the economic crisis in Cuba. Let’s see how they live and how healthy they are.

The Guna are presented by Guyenet as consumers of a large amount of white sugar. Actually, according to his calculations, the “high” consumption of white sugar (sucrose) is 36g/d. That amount includes 1/3 cup of sweetened drink per day. That is a consumption of a 12-oz soda per 4-5 days. According to this study, 23% of their calories come from dietary fat.

Is this an adequate example that you can consume a large amount of sugar and still not have obesity? In my opinion, this example tells us nothing about what happens in a Westernized culture. If, for example, they live on islands and due to their high fish intake they have a good omega-3 to omega-6 ratio, it is possible that this protects them from their —apparently very low— white sugar consumption.

The case of the Cuban economic crisis from 1989 to 2000 is another of the examples presented by Guyenet. As we can see in the graph below, which is included in the article linked by Guyenet, the energy intake was reduced around 750 kcal in the center years of the aforementioned period.

More data: the diet was very low in fat (13% of calories in 1993) and in protein, with only 46 g/d, only 10% of caloric intake (see):

The population had to walk or to use bicycles everywhere due to the lack of motorized transport (see):

Starting in 1990, this new situation, which produced changes in the nutritional status of some groups of the population, combined with a forced increase in the level of physical activity. As a result of the general scarcity of motorized transport, the population began to walk and use bicycles for their daily movements.

There was an increase in the cases of: anemia in pregnant women, chronic protein deficiency, underweight pregnant women, underweight births, etc. In other words, with a nutritionally-very poor diet, based on sugar and rice, when forced to exercise, and consuming much fewer calories than recommended, this population lost weight in the short term (see). And this happened despite consuming around 150g of sugar per day.

The prevalences of obesity in Havana were 11.9 percent, 5.4 percent, and 9.3 percent in 1982, 1994, and 1998, respectively.

As a summary, they lost weight transiently by being hungry with an unsustainable low-energy diet, that was nutritionally deficient and very low in fat, while they were forced to have more physical activity, just as if they were in a concentration camp. Under these conditions, sugar was not enough to produce obesity in the short term. Okay.

As for the Hadza, they apparently consume a large amount of honey during part of the year (source) and generally they do not have excess weight. Assuming that the food that is brought into their camps represents the foods that are available in each month of the year, the following graph would show that a high consumption of honey only happens during, approximatedly, half of the year.

It should be noted that what they consume is neither white sugar nor refined honey: it is honey with bee larvae, which contains more protein and fat than commercially processed honey:

Although only small amounts of protein (mainly free amino acids) are found in liquid honey (Bogdanov et al. 2008), wild honeys contain higher levels of protein and fat, most likely because they contain trace amounts of bee larvae, whereas cleaned and commercially processed honey does not (source)

On the other hand, the diet of the Hadza seems to be very low in dietary fat, with only 11% of the calories coming from fat (see). Could this be the key factor that makes honey not fattening for the Hadza? In any case, there may be other relevant factors, such as the speed of ingestion and honey’s texture, or low levels of omega-6 in their diet.

The Hadza’s story is an interesting one.

Do these stories refute the sugar hypothesis? If they do, we need a better hypothesis that is also based on physiology, not to go back to worship the energy balance pseudoscience.

And if the sugar hypothesis is unambiguously refuted, whatever hypothesis steps up as the next prime suspect has to be very carefully considered. (i.e., not the simplistic notion that people eat too much and move too little). We need a hypothesis that holds the promise of explaining the epidemics everywhere. Gary Taubes

The three studies that NuSI funded:

  • The pilot experiment (Kevin Hall)
  • DIETFITS experiment (Cristopher Gardner)
  • The weight maintenance experiment (David Ludwig)

As we have already discussed in the 3rd part of this analysis David Ludwig’s experiment, I focus on the other two.

” Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men “

In this 2016 video we have Kevin Hall bragging about refuting the carbohydrate-insulin model with a not-randomized pilot experiment!! (diets are applied in one sequence only and there is no control group) while on the background there is a poster whose title says the opposite of what he explains in the video (see): “Energy expenditure increases following an isocaloric ketogenic diet in overweight and obese men.”

The increase he found wasn’t enough for him, because he set a requirement as high as he liked so the difference between diets was reported as irrelevant (see): he demanded a difference of 300-600 kcal/d.

These data, although somewhat confounded by ongoing weight loss, suggest that large isocaloric changes in the proportion of dietary carbohydrate to fat transiently increase EE by only ∼100 kcal/d after adjusting for body weight and composition. […] the carbohydrate–insulin model predicts that the KD would lead to increased EE, thereby resulting in a metabolic advantage amounting to ∼300–600 kcal/d (21, 22). Our data do not support EE increases of that magnitude.

So, we see that Hall thinks of a 100 kcal/d difference between diets as small. It is awkward, though, because Hall believes that 10 kcal/d of caloric surplus explain the current obesity epidemic in the USA (see). In other words, he says a 100 kcal/d difference between diets is too little because he demands 300-600 kcal/day to the ketogenic diet, just because he wants to demand that. This is god-level zealotry. And he gets it published in a scientific journal!

We did not include a control group that did not receive the KD or a group that had the diets delivered in the reverse order.

The order of the diets can make, for example, the energy expenditure greater during the first diet, since no weight has yet been lost and there is more fat and non-fat mass. That’s why it was a pilot study, because it was non-randomized and not designed to detect differences between groups. It was not meant to draw conclusions, but rather to learn how to properly design a subsequent bigger study that would have enough statistical power (see). Did you say that the study has limitations? It doesn’t matter: when you think it can be useful to support your pseudoscience, you use the outcome as if it were a randomized experiment.

Moreover, in this experiment the authors (Kevin Hall among them) failed to keep the weight of the participants stable (see).

A major limitation of our study is the unintentional weight loss. Despite slight positive energy balance during the chamber days, the overall negative energy balance amounted to ~300 kcal/d and was likely due to greater spontaneous physical activity on nonchamber days.

It is an invaluable practical demonstration of the actual value of Hall’s ideas about how our body works. Bias? Cognitive dissonance? Zealotry? It’s Kevin Hall, PhD.

Guyenet summarizes this experiment saying that there are no differences. The article says the opposite of what Guyenet says, despite the limitations of the study, which probably played against the ketogenic diet:

The isocaloric KD was not accompanied by increased body fat loss but was associated with relatively small increases in EE that were near the limits of detection with the use of state-of-the-art technology.

“Was asociated.” Another inconvenient truth for Guyenet.

” Effect of Low-Fat vs. Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion “

This experiment, led by Christopher Gardner, is commented in this blog post. Since in that link we can read a detailed analysis, I go directly to the relevant facts. The  participants were supposedly doing a caloric restriction of 500 kcal/d. We see in the following figure the evolution of their body weight:

evolpeso2

After 12 months, one group lost a mean of 5.3 kg while the other one lost a mean of 6.0 kg:

Weight change at 12 months was −5.3 kg for the HLF diet vs −6.0 kg for the HLC diet (mean between-group difference, 0.7 kg [95% CI, −0.2 to 1.6 kg]).

There was a difference between diets, but it didn’t reach statistical significance. But the important thing is that in the second half of the study both groups gained weight back. Why did they regain part of the lost weight? Is this what the CICO hypothesis predicts? The problem for Guyenet is as follows:

  • If he claims that the outcome shows no differences between diets, he has to assume that the intake data is reliable. Otherwise he doesn’t know if the caloric restriction was the same in both groups.
  • If he thinks that eating less is a valid weight loss strategy, he can’t accept the intake data as correct.

If he says that the intake data of this study are reliable, this experiment shows that the hypocaloric diet is a failure as a weight loss diet. That would be another refutation of Guyenet’s hypothesis. Are reliable the intake data from this study, Guyenet?

Taubes makes this point: “it’s the same data that you said that they were not reliable because they were self-reported”.

NOTE: Kevin Hall’s low level as a scientist and his lack of rigor are evident in his articles (seesee).

NOTE: it’s not obvious that nonindustrialized populations such as the Hadza have a high energy expenditure that allows them to eat as much as they want and not get fat (source).

Go to the conclusions
Go to the fifth part
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Go to the third part
Go to the second part
Go to the first part

Debate Taubes-Guyenet. Mi análisis (IV)

(English version: click here)

Mis notas para el cuarto (y penúltimo) segmento del debate, y mis comentarios tras las mismas:

  • [GT 1h33m] La hipótesis del azúcar: agregas algo que está en una dieta/estilo de vida occidental a las poblaciones, obtienes explosiones de obesidad y diabetes. Mi hipótesis es que el azúcar es ese algo que hay que agregar. Puede que sean las bebidas azucaradas.
  • [SG 1h34m] Siempre es posible contar historias para salvar tu hipótesis, pero eso no necesariamente hace que la historia sea correcta. No tenemos ninguna evidencia para apoyar lo que Gary acaba de decir. Cito a Christopher Hitchens: ‘Lo que se afirma sin evidencia, se puede descartar sin evidencia’. Y así es como me siento yo sobre esta historia en particular.
  • [SG 1h35m] Voy a hablar sobre tres culturas diferentes que consumen mucho azúcar y no tienen obesidad. Los Hadza en Tanzania consumen mucha miel. El 15% de su ingesta calórica proviene de la miel. Esto es tanto como los estadounidenses comen, y comen fruta además de esto. Los pigmeos en el Congo también comen mucha miel. Hasta el 80% de las calorías pueden provenir de la miel durante la temporada de lluvias. Y están delgados.
  • [SG 1h38m] Si comes mucha azúcar pero todo lo demás está en su sitio, el azúcar no es suficiente para hacernos engordar. No estoy diciendo que no contribuya, creo que el azúcar sí contribuye, pero no es el único responsable como argumenta Gary. Los Guna de Panamá son la tercera población. Estos consumen azúcar blanco.
  • [Joe Rogan 1h39m] En civilizaciones no occidentalizadas quemas tantas calorías …
  • [SG 1h40m] Estoy 100% de acuerdo contigo.
  • [Joe Rogan 1h40m] Lo que pasa con la quema de calorías es que en los estilos de vida occidentalizados simplemente se existe, no hacen nada para quemar la mierda. Creo que lo que Gary está tratando de decir es que si tienes este estilo de vida y con este estilo de vida consumes azúcar, vas a engordar. No creo que puedas comparar eso con los atletas, y no creo que puedas comparar eso con los recolectores-cazadores. Recuerdo que hacía ejercicio 4 h/d y comía todo lo que me apetecía (refrescos, galletas, etc.) y el único peso que ganaba era músculo.
  • [SG 1h42m] Estoy de acuerdo en que no es tan simple como el azúcar, pero Gary sostiene que el azúcar es la causa principal de la obesidad y que la actividad física no importa, que la ingesta de calorías no importa.
  • [GT 1h42m] Cuando hablamos de la causa de la obesidad, no creo que las personas obesas se vuelvan obesas porque son sedentarias.
  • [Joe Rogan 1h42m] ¿No crees que un atleta tiene una alta demanda de azúcar y la quemará?
  • [GT 1h42m] Absolutamente.
  • [GT 1h43m] ¿Puedo volver a los Guna? Stephan llama a mis historias “historias”, que lo son, pero él llama a las suyas “evidencia”. Acerca de los Guna [GT lee un texto de un intercambio de correos electrónicos con SG] comen una cantidad baja de azúcar (32 libras de azúcar al año) y no sabemos cómo esa cantidad ha cambiado con los años. [Se escucha a Guyenet reír mientras habla Taubes] Tampoco me creo los datos de los Guna urbanizados, que aparentemente beben sólo 3 botes de bebidas azucaradas por semana, y que consumían más azúcar en el lugar del que vienen.
  • [GT 1h45m] Stephan está constantemente citando estudios que sólo hablan de una hipótesis, como los estudios de sobrealimentación, o que están mal construidos y mal hechos. Acerca de los Hadza, ya le dije que no creo que sea una refutación de mi hipótesis, ya que mi hipótesis es que cuando agregas azúcar a la dieta de cualquier población obtienes obesidad. Puede ser que los Hadza hayan estado comiendo miel durante miles de años. Puede ser que cuando emigraron a esta área tuvieran obesidad. No creo que encontrar una población de cazadores-recolectores que coma miel y no tenga obesidad sea una refutación, Stephan sí lo cree.
  • [GT 1h47m] Mi organización sin fines de lucro financió un estudio con 40 niños que tenían hígado graso. Podían comer fruta, todo lo que quisieran, pero sin azúcar agregada ni bebidas azucaradas. La enfermedad del hígado graso se resolvió. No podemos hablar del mecanismo. Puede ser que fuera por la pérdida de peso.
  • [GT 1h48m] Sobre el metaanálisis de Hall, se juntó toda la ciencia basura que se ha hecho en los últimos 50 años, mientras se ignora la calidad de los estudios. E hicieron un mal trabajo. En un estudio que verifiqué, incluso confundieron una disminución de 400 kJ en el gasto de energía con una disminución de 400 kcal [NT 400kJ = 95kcal].
  • [GT 1h49m] Tienes que hacer los estudios correctos si quieres obtener la respuesta correcta.
  • [GT 1h50m] Stephan rechazó abiertamente este estudio que NuSi financió con 12 millones de dólares. Básicamente, hay 3 personas que están convencidas de que todo lo que la gente como yo dice está mal. Parecen no cansarse nunca. Kevin Hall afirma que ha refutado el modelo carbohidratos-insulina. Cuando su estudio lo apoya, él se mueve para averiguar por qué el estudio está equivocado. Todos hacemos lo mismo. El objetivo es, en última instancia, hacer el estudio correcto, porque tenemos que recordar lo que está en juego aquí.
  • [GT 1h51m] Durante décadas las personas han pensado como Stephan, y hay una hipótesis alternativa y tenemos que averiguar su es correcta porque las personas se están muriendo.
  • [SG 1h51m] Esta explicación alternativa se ha investigado exhaustivamente incluso con estudios financiados por tu propia organización, NuSi. 2 de los 3 estudios fueron una clara refutación de tu hipótesis. Existe una notable correlación entre los estudios que socavan tus creencias y que creas que esos estudios son basura. [Guyenet ríe]
  • [SG 1h52m] Sobre los estudios de Hill y Peters, si no puedes encontrar problemas específicos con los estudios, no puedes desecharlos sin más.
  • [GT 1h53m] Te indiqué un problema con el estudio: fue diseñado en base a la suposición que debía probar.
  • [SG 1h52m] Ok, no fue diseñado como Gary quería que fuera diseñado.
  • [SG 1h53m] Los Guna. La base principal del libro de Gary es que cuando el azúcar entra en estas culturas, engordan. Estoy señalando 3 culturas que comen altos niveles de azúcar y no están gordas. En la referencia [22] podemos ver que en la crisis económica cubana aumentó la ingesta de azúcar, un 28% de la ingesta calórica, el doble de lo que consumen los estadounidenses. El consumo de calorías bajó y tuvieron que caminar mucho debido a la falta de gasolina. Si Gary tiene razón y las calorías no importan, si sólo importan los carbohidratos refinados y el azúcar, la obesidad debería haberse disparado. La prevalencia de obesidad se redujo a la mitad: del 14% al 7%. La tasa de personas con peso muy bajo aumentó ligeramente. Tan pronto como volvieron a su dieta original, la obesidad aumentó.
  • [GT 1h57m] Tendría que leer el estudio para descubrir cuál es el problema.
  • [Joe Rogan 1h57m] ¿Qué pasa con los estudios de NuSi?
  • [GT 1h57m] Bueno, este es un juego al que juega la gente. Mi problema con Stephan es que habla como si lo supiera, con esta autoridad.
  • [SG 1h58m] Los 2 primeros estudios refutaron la hipótesis de Gary. Gary es prácticamente la única persona que piensa que no refutó sus creencias. La comunidad científica es bastante unánime.
  • [GT 1h59m] El primer estudio fue un estudio piloto que, depende de lo que mires, puedes pensar que refuta una creencia. Kevin Hall tiende a creer que la obesidad es un problema de equilibrio energético, David Ludwig y sus colegas tienden a creer lo que yo creo. Si crees que Kevin interpretó correctamente su estudio (el financiado por NuSi), entonces no apoya que los carbohidratos sean responsables de estimular la insulina y que la insulina esté impulsando la acumulación de grasa. El estudio de David Ludwig reportó lo contrario. David ha criticado el estudio de Kevin y Kevin ha criticado el estudio de David. El estudio intermedio fue un estudio en condiciones de vida libre realizado por Christopher Gardner. La dieta baja en carbohidratos no era una dieta significativa baja en carbohidratos y les dijeron a ambos grupos que no comieran azúcares y granos refinados, que, según mi hipótesis, son los carbohidratos más engordantes. Probaron dos dietas y ninguna de ellas tenía azúcar ni pan blanco. Fue un estudio mal hecho, no respondió a la pregunta.
  • [SG 2h3m] El déficit calórico fue autoreportado, por lo que no es realmente exacto.
  • [SG 2h4m] Hubo una diferencia de 2 veces en la ingesta de carbohidratos.
    [GT 2h4m] Si crees en lo que dicen los cuestionarios de frecuencia de alimentos, algo que acabas de decir que no sabemos si se puede creer.
  • [SG 2h4m] Estoy de acuerdo contigo en que los carbohidratos refinados y el azúcar son los tipos de carbohidratos que más engordan.
  • [Joe Rogan 2h5m] ¡Oh, dios mío!, ¿podemos acordar algo?
  • [GT 2h5m] La pregunta es ¿por qué? ¿Es porque la gente los come en exceso?
    [SG 2h5m] Si crees en la hipótesis de Gary, ya que cualquier tipo de carbohidrato aumenta los niveles de insulina más que la grasa, si eso es importante para la pérdida de grasa, estos grupos tuvieron una diferencia de 2 veces en la ingesta de carbohidratos, aunque eran carbohidratos predominantemente saludables. Se debería de haber visto algo, no la misma cantidad de pérdida de peso en ambos grupos.
  • [Joe Rogan 2h5m] Pero no son altos en azúcar, ¿verdad? Tu discurso siempre ha sido sobre el azúcar, ¿verdad?
  • [GT 2h5m] Stephan tiene razón: defiendo mi hipótesis. Él hace lo mismo. Todos lo hacemos. Y cada estudio realizado tiene muchas razones para no creerlo. Es por eso que las replicaciones independientes es algo que siempre quieres que se haga.

La falacia ad populum

[SG 1h58m] Los 2 primeros estudios refutaron la hipótesis de Gary. Gary es prácticamente la única persona que piensa que no refutaron sus creencias. La comunidad científica es bastante unánime en esto.

La falacia ad populum es la apelación a la popularidad de una opinión como una razón para aceptarla. La cantidad de personas que creen una afirmación es irrelevante en relación a si es correcta o no. Taubes ha reconocido que sus afirmaciones van en contra de la opinión prevaleciente.

Guna, Cuba y Hadza

Creo que sería un error ignorar los ejemplos de los Guna, Hadza o la crisis económica en Cuba. Vamos a ver cómo viven y qué salud tienen.

Los Guna son presentados por Guyenet como consumidores de una gran cantidad de azúcar blanco. En realidad, de acuerdo con sus propios cálculos, ese consumo “elevado” de azúcar blanco (sacarosa) es de 36 g/d. Incluido en ese cálculo está 1/3 de taza (cups) de bebida azucarada al día. Teniendo en cuenta que un bote equivale a 1.5 tazas, eso es un consumo de un bote de bebida azucarada cada 4-5 días. Según este estudio, un 23% de las calorías proceden de grasa dietética.

¿Es éste un ejemplo adecuado de que se puede consumir una gran cantidad de azúcar y aun así no tener obesidad? Para mí este ejemplo no sirve para demostrar nada sobre lo que sucede en una cultura occidentalizada. Si por ejemplo al vivir en islas y gracias a un alto consumo de pescado su dieta tiene el ratio adecuado de omega-3 a omega-6, es posible que eso les proteja de ese consumo —aparentemente muy bajo— de azúcar blanco.

El caso de la crisis económica cubana de 1989 a 2000 es otro de los ejemplos presentados por Guyenet. Como vemos en la gráfica, sacada del artículo enlazado por Guyenet, durante esos años la ingesta energética se desplomó unas 750 kcal a mediados del referido periodo.

No sólo eso: la dieta era bajísima en grasa (13% de las calorías en 1993) y en proteína, con sólo 46 g/d, un 10% de la ingesta calórica (ver):

Y a esto le unimos que se veían obligados a ir andando o en bicicleta a todas partes por falta de vehículos a motor (ver):

A esa situación nueva, que produjo modificaciones del estado nutricional en algunos grupos de la población, se sumó, a partir de 1990, el aumento forzoso de la actividad física: a consecuencia de la escasez generalizada del transporte motorizado la población comenzó a caminar y a usar la bicicleta para sus desplazamientos cotidianos.

Hubo incremento en los casos de: anemia en embarazadas, deficiencia crónica de proteína, embarazadas con peso por debajo de lo normal, nacimientos con niños faltos de peso, etc. Es decir, que con una dieta muy pobre nutricionalmente, basada en azúcar y arroz, obligados a tener actividad física, y consumiendo muchas menos calorías de las recomendadas, perdieron peso a corto plazo (ver). Y lo hicieron a pesar de consumir unos 150g diarios de azúcar.

The prevalences of obesity in Havana were 11.9 percent, 5.4 percent, and 9.3 percent in 1982, 1994, and 1998, respectively.

En definitiva, perdieron peso transitoriamente pasando hambre con una dieta insostenible energéticamente, nutricionalmente deficiente y muy baja en grasa, y forzados a tener una mayor actividad física, todo ello como si estuvieran en un campo de concentración. En esas condiciones el azúcar no fue suficiente para producir obesidad a corto plazo. Pues vale.

En cuanto a los Hadza, aparentemente consumen una gran cantidad de miel durante parte del año (fuente) y en general no tienen nada de exceso de peso. Dando por supuesto que la comida que llega a los poblados representa lo que está disponible en cada mes del año, el siguiente gráfico mostraría que un elevado consumo de miel sólo existe durante la mitad del año, más o menos.

Hay que resaltar que lo que consumen no es azúcar blanco y ni siquiera es miel purificada: es miel con larvas de abeja, que contiene más proteína y grasa:

Although only small amounts of protein (mainly free amino acids) are found in liquid honey (Bogdanov et al. 2008), wild honeys contain higher levels of protein and fat, most likely because they contain trace amounts of bee larvae, whereas cleaned and commercially processed honey does not (fuente)

Por otro lado, la dieta de los Hadza parece ser bajísima en grasa dietética, con sólo un 11% de las calorías procedentes de grasa (ver). ¿Puede ser ese dato clave para que la miel no les engorde? Podría haber otros factores relevantes, como por ejemplo la velocidad de ingestión y textura de la miel, o bajos niveles de omega-6 en su dieta.

Sea como fuere, el de los Hadza es un caso interesante.

¿Estas historias refutan la hipótesis del azúcar? Si lo hacen, necesitamos una hipótesis mejor, una que también esté basada en la fisiología, no seguir adorando la pseudociencia del balance energético.

Y si la hipótesis del azúcar se refuta de manera inequívoca, cualquiera que sea la siguiente hipótesis que se postule como principal sospechosa  debe ser considerada cuidadosamente (es decir, no la simplista noción de que las personas comen demasiado y se mueven muy poco). Necesitamos una hipótesis que pueda mantener la promesa de explicar las epidemias en todas partes. Gary Taubes

Los tres estudios que financió NuSi:

  • El experimento piloto (Kevin Hall)
  • Experimento DIETFITS (Cristopher Gardner)
  • El experimento de mantenimiento de peso (David Ludwig)

Como del experimento de David Ludwig ya hemos hablado en la tercera entrega de este análisis, me centro en los otros dos.

Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men

En este vídeo de 2016 tenemos a Kevin Hall alardeando de haber refutado el modelo carbohidratos-insulina con un experimento piloto ¡¡no aleatorizado!! (pues sólo se aplican las dietas en un orden y carece de grupo control) teniendo a sus espaldas un póster cuyo título decía todo lo contrario de lo que él explicaba en el vídeo (ver): “El gasto energético aumenta después de una dieta cetogénica isocalórica en hombres con sobrepeso y obesos”.

Pero a él el aumento no le parecía suficiente, porque puso el listón de exigencia donde le vino en gana para que la diferencia pareciese poco importante (ver): pedía una diferencia de 300-600 kcal/d.

These data, although somewhat confounded by ongoing weight loss, suggest that large isocaloric changes in the proportion of dietary carbohydrate to fat transiently increase EE by only ∼100 kcal/d after adjusting for body weight and composition. […] the carbohydrate–insulin model predicts that the KD would lead to increased EE, thereby resulting in a metabolic advantage amounting to ∼300–600 kcal/d (21, 22). Our data do not support EE increases of that magnitude.

Estos datos, aunque algo confundidos por la pérdida de peso en curso, sugieren que los grandes cambios isocalóricos en la proporción de carbohidratos en la dieta con respecto a la grasa aumentan la EE de manera transitoria en solo 100 kcal/d después de ajustar el peso corporal y la composición. […] el modelo de carbohidrato-insulina predice que la KD conduciría a un aumento de la EE, lo que resultaría en una ventaja metabólica que asciende a –300–600 kcal / d (21, 22). Nuestros datos no soportan incrementos de EE de esa magnitud.

A Hall 100 kcal/d de diferencia entre dietas le parecen poca cosa. Es curioso, porque el propio Hall cree que 10 kcal/d de superávit calórico explican la actual epidemia de obesidad en USA (ver). O sea que 100 kcal/d de diferencia entre dietas le parece poca cosa porque él exige de 300 a 600 kcal/d de diferencia a la dieta cetogénica, porque le apetece exigir eso. Esto es fanatismo nivel dios. ¡Y lo publica en revistas científicas!

We did not include a control group that did not receive the KD or a group that had the diets delivered in the reverse order.

No incluimos un grupo de control que no recibiera la dieta cetogénica ni un grupo que recibiera las dietas en el orden inverso.

El orden de las dietas puede hacer, por ejemplo, que el gasto energético sea mayor durante la primera dieta, pues todavía no se ha perdido peso y hay más masa grasa y no grasa. Por eso era un estudio piloto, porque era no aleatorizado y no pensado para detectar diferencias entre grupos. No estaba destinado a sacar conclusiones, sino a aprender para hacer un estudio posterior bien hecho y con potencia estadística suficiente (ver). ¿Que el estudio tiene limitaciones? ¡Qué más da! Si crees que sirve para hacer avanzar tu pseudociencia usas el resultado como si fuera un experimento aleatorizado.

En este experimento, además, los autores (Kevin Hall entre ellos) fracasaron en el propósito de mantener estable el peso de los participantes (ver).

A major limitation of our study is the unintentional weight loss. Despite slight positive energy balance during the chamber days, the overall negative energy balance amounted to ~300 kcal/d and was likely due to greater spontaneous physical activity on nonchamber days.

Una limitación importante de nuestro estudio es la pérdida de peso involuntaria. A pesar del ligero balance de energía positivo durante los días de cámara, el balance de energía negativo total ascendió a aproximadamente 300 kcal/día y probablemente se debió a una mayor actividad física espontánea en días sin cámaras.

Es una impagable demostración práctica de lo que valen las hipótesis de Hall sobre cómo funciona nuestro cuerpo. ¿Sesgo? ¿Disonancia cognitiva? ¿Fanatismo? Es Kevin Hall, PhD.

Guyenet resume este experimento como que no hay diferencias. El artículo dice lo contrario que Guyenet, a pesar de las limitaciones del mismo, que probablemente jugaban en contra de la dieta cetogénica:

The isocaloric KD was not accompanied by increased body fat loss but was associated with relatively small increases in EE that were near the limits of detection with the use of state-of-the-art technology.

La KD isocalórica no estuvo acompañada por un aumento de la pérdida de grasa corporal, pero estuvo asociado a aumentos relativamente pequeños en el EE [gasto energético] que estaban cerca de los límites de detección con el uso de tecnología punta.

“Was associated”. Otra verdad inconveniente para Guyenet.

Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion

Este experimento, que es liderado por Christopher Gardner, está comentado en esta entrada del blog. Como allí está el análisis detallado, voy directamente a lo relevante. Se supone que los participantes estaban haciendo una restricción calórica de 500 kcal/d. Y ésta que vemos es la evolución del peso corporal:

evolpeso2

En un grupo se perdieron 5.3 kg y en el otro 6.0 kg al cabo de 12 meses:

Weight change at 12 months was −5.3 kg for the HLF diet vs −6.0 kg for the HLC diet (mean between-group difference, 0.7 kg [95% CI, −0.2 to 1.6 kg]).

Hubo diferencia entre dietas, pero no alcanzó significancia estadística. Pero lo relevante es que en la segunda mitad del estudio recuperaron peso ambos grupos. ¿Por qué recuperaron peso? ¿Es esto lo que la hipótesis CICO predice? Éste es el problema para Guyenet:

  • Si dice que no hay diferencias entre dietas, tiene que dar por buenos los datos de ingesta. De otro modo, no sabría si la ingesta energética fue la misma en ambos grupos.
  • Si cree que “comer menos” es un método eficaz para adelgazar y mantener el peso perdido, tiene que poner en duda los datos de ingesta.

Si da por buenos los datos de ingesta, este experimento demuestra que la dieta hipocalórica es un fraude como dieta de adelgazamiento. Esto sería una nueva refutación de sus propias hipótesis. ¿Son fiables los datos de ingesta de este estudio, Guyenet?

Y así se lo hace ver Taubes:

[GT 2h4m] Si crees en lo que dicen los cuestionarios de frecuencia de alimentos, algo que acabas de decir que no sabemos si se puede creer.

NOTA: El bajo nivel como científico y la falta de rigor de Kevin Hall quedan patentes en sus artículos (ver,ver).

NOTA: no demos por obvio que pueblos no industrializados como los Hadza tienen un gran gasto energético que les sirve para comer lo que quieran y no engordar (fuente).

Ir a las conclusiones
Ir a la quinta entrega
Ir a la cuarta entrega
Ir a la tercera entrega
Ir a la segunda entrega
Ir a la primera entrega

Taubes-Guyenet debate. My analysis (III)

(Versión en español: hacer click aquí)

My notes on the 3rd segment of the debate and my comments below them:

  • [SG 1h2m] When you use accurate methods you find that people with magical metabolism, those who have obesity and don’t eat very much, seem to not exist any more.
  • [SG 1h3m] I want to talk about studies where they increase calorie intake. If we want to understand why people get fat, we can look at studies that overfed people on fat or carbohydrates exclusively. In one study they calculated the energy requirements and then they increased that by 50% with fat or carbohydrate. This is Horton’s study, reference [16]
  • [SG 1h4m] If Gary’s hypothesis is correct, these people should have gained fat in the carbohydrate overfeeding but not the fat overfeeding. These people were in a metabolic ward, so the researchers could monitor everything. No cheating. No inaccuracy.
  • [SG 1h6m] What they found is that at the end of a 2-week period of overfeeding, the carb and fat group gained exactly the same amount of body fat. In a 2nd study they did the same thing and found the same result. 3-week-long experiment. Different insulin responses, different amounts of carbohydrate and fat, exact same amount of fat gain. This demonstrates that insulin is not what gets fat into fat tissue. Calorie intake is what controls that.
  • [GT 1h7m] The paradigm you work in determines the questions you ask. This experiment assumes people get fat by overfeeding. They think they are just doing what happens naturally. They are answering the question of whether people can get fat by overfeeding. This experiment is built on the paradigm they want to test.
  • [GT 1h7m] [Comments about the relationship of Peters JC, Hill JO. with Olestra and the sugar industry]
  • [GT 1h10m] 10 kcal/d, less than a bite of food, explains obesity. How do we explain those 10 kcal/d? Is the brain somehow regulating that? Or is it due to a disregulation in the body that traps fat in the fat cells or prevents fat from being used for fuel? If someone drinks 5 beers a day, may be he/she only stores 10-20 kcal/d, how does that happen and why does it go here and not there?
  • [GT 1h12m] It is not that hard to imagine that someone during a relative famine can store 10 kcal/d. If they are only eating 1200, 10 get stuck in the fat cells and 1190 are excreted or expended. Nothing in the laws of physics says so. In animal models you can disassociate obesity from eating too much.
  • [Joe Rogan] In essence you’re saying that even if someone is consuming a lot or a few calories each day, 2000 kcal/d, if those calories are consumed in the form of sugar, the body will store part of them, even if the body is not receiving enough food, while if you consume protein, vegetables, etc. your body will not do that.
  • [GT 1h13m] This brings us to the subject of evidence and mechanism.
  • [Joe Rogan] But you’re saying that, right? If two people follow the same caloric intake, one of them with 2000 kcal/d of chicken, fish, vegetables, and the other one of 2000 kcal/d of milkshakes and sugary drinks, pasta and BS, that person is going to gain a certain amount of calories and put them to fat, regardless [of calories].
  • [GT 1h14m] Yes, that is the hypothesis. And that hypothesis can be tested. Stephan thinks it has been tested 80 times, I think they have done a bad job of testing it. And we both tend to reject the studies that we do not like, when we define “don’t like” as not having the answer that we think is correct.
  • [Joe Rogan] But You, Stephan, you think that this is not correct. You say that in the study where they add additional fat and additional carbohydrates, they both gain the same amount of weight.
  • [SG 1h14m] That’s right. If Gary’s hypothesis is correct, you have to see different levels of fat gain.
  • [Joe Rogan] It was a short term study?
  • [SG 1h14m] Yeah, it was a short-term study. 2 and 3 weeks. It is very short. But if insulin is the hormone that puts fat into fat cells, you should see any kind of difference, some kind of effect on fat gain.
  • [GT 1h15m] One problem with overfeeding studies is that one of the hypothesis says energy balance is dependent on the macronutrient content of the food. Therefore you are going to have different levels depending on what the macronutrient content is.
  • [GT 1h16m] Ludwig’s study is an example. They saw different levels of energy expenditure depending on the carbohydrate content of the diet. The lower the carbohydrate the higher the energy expenditure.
  • [GT 1h18m] Experiments should take into account all the competing hypothesis. If there is a threshold effect of insulin, which actually there is, you don’t actually expect to see any difference between groups, since they are both in the plateau of the insulin response. If it actually is activated in both groups, both hypothesis predict the same fat gain.
  • [GT 1h20m] Anecdote about an obese friend. My hypothesis is that he would have gained weight regardless of eating or not 300 kcal extra a day, because his insulin was elevated.
  • [SG 1h20m ] It is easy to tell stories, it is not easy to tell stories that are supported by scientific evidence.
  • [SG 1h20m ] 29 studies have measured energy expenditure on diets differing on carbohydrates and fat content. When you put all these studies together, it makes almost no difference in the metabolic rate if people are eating carbohydrates or fat. In fact, the very small difference favors high-carbohydrate diets.
  • [SG 1h21m] The study Gary says (Ludwig’s) is the one that reports the biggest difference among those 28+1 studies.
  • [SG 1h22m] In Ludwig’s study, some of the participant’s data are literally physically impossible. If you remove the clearly erroneous data, the study no longer reports a higher energy expenditure on a low-carbohydrate diet and is consistent with the previous 28 studies.
  • [SG 1h23m ] In regards of the 10 kcal/d, Gary, I continue to have the feeling that you don’t understand human energetics, because that is not how it works.
  • [GT 1h23m] You are insulting me, you have to stop doing that. You keep acting as if you think I am an idiot.
  • [SG 1h23m] It only takes a small amount of extra calories to make someone gain fat. As they get fat their calorie needs go up.
  • [GT 1h24m] How does the brain do that?
  • [SG 1h24m] I didn’t say the brain does that. The point is that by the time they have obesity, they are consuming 20-35% more calories than they were when they were lean. It is not one of 2 cokes a day that is allowing them to remain obese, they are consuming 20-35% more. It’s not 10 extra calories.
  • [SG 1h26m] If you eat 10 kcal more than you need, you store them.
  • [SG 1h27m] Sugar intake has been declining in the USA during the last 20 years, it peaked in 1999 and it is now 15-23% lower than it was in 1999. Obesity has increased during the last 20 years. The same in the UK.
  • [SG 1h29m] Taubes counterargument is that the amount of sugar we consumed 20 years ago may influence us today.

Arrogance is not the same as assertiveness

In this segment we have Guyenet again qualifying Taubes’ opinions as story-telling, presuming to defend an opinion based on scientific evidence and stating that his interlocutor does not understand the energetics of the human body. I insist on the warning that we should not take Guyenet’s arrogance as a symptom that he is right or that he knows what he is talking about. Arrogance is only a sign of arrogance, nothing else. And do not mistake arrogance for assertiveness.

Guyenet disinforms about sugar

I start with the end of the debate segment. Guyenet cites at 1h27m the fact that, in the USA and in the UK,  the rate of obesity continues to rise although sugar consumption has been declining in the last decades. The argument is inappropriate for a person with a college degree, specially if this person has a PhD. It doesn’t matter how arrogant he is: his argument is unquestionably stupid.

Why is it stupid? It is explained in these two articles:

In the following graph I show the annual sugar intake in the USA (blue curve) from 1980 to 2015 and the annual increment in the percentage of obese adults (orange curve):

As we see, there could be a causal relationship between sugar consumption and body weight, since changes in sugar consumption correlate with the growth rate of obesity. When the consumption of sugar goes up, obesity grows faster. And there is also a good correlation in the case of sugar-sweetened beverages. This is not proof of a cause-and-effect relationship, but a cause-effect relationship can’t be ruled out with these data.

Well, Guyenet, who has a Ph.D., assumes that if sugar is fattening there must be a direct relationship between sugar consumption (blue curve) and the integral of the orange curve (i.e. the accumulated value), something that does not make any sense when assuming that sugar is fattening, which is the hypothesis that he wants to refute. If he had just represented the data in another way, as we have seen in the graph above, he would have found that direct relationship that he believes does not exist.

pastedimage

And since he doesn’t find a direct relationship where nobody expects it to be, he assumes that sugar cannot be an important factor in the obesity epidemic. Regardless of whether this is true or not, regardless of the relevance of sugar in the obesity epidemic, Guyenet’s argument is blatantly wrong. For more detailed explanations of Guyenet’s mistake, I refer to the two blog posts (English language in both of them) I linked above.

Let’s not mistake arrogance for competence.

False dichotomy fallacy

[SG 1h6m] This demonstrates that insulin is not what gets fat into fat tissue. Calorie intake is what controls that.

Even if Guyenet were right about insulin, it doesn’t follow that calorie intake controls fat accumulation. He is using the false dichotomy fallacy. His claim that calorie intake is what controls body fat accumulation has to be proved.

Taubes’ arguments

Some of Taubes’ arguments seem remarkable to me:

  • 10 kcal/d, which is less than a mouthful of food, explains obesity. How do we explain those 10 kcal/d?
  • It is not so difficult to imagine that someone during a relative famine can store 10 kcal/d. If they are only eating 1200 kcal/d, 10 remain in the fat cells and 1190 are excreted or spent.
  • In animal models one can find the dissociation between obesity and eating too much.

Guyenet avoids addressing the first argument, as I explain below. Guyenet says that eating too little you cannot get fat, as we saw in part II of my analysis. In regards of the third one, and this is something we have seen in this blog, experiments with animals do show that they can gain body fat without an increased intake. How can Guyenet explain his irrational belief that overeating is a requirement for weight gain in humans?

Overconsumption experiments

This is one of the most interesting parts of the debate. Guyenet begins by citing the overconsumption experiment by Horton et al. 1995 in which extra food is given in the form of fat or in the form of carbohydrates. And Guyenet says, literally, that if the carbohydrate-insulin hypothesis were correct, differences between both diets should have come up, and he says that fat gain was the same in both groups.

We have already commented this experiment in the blog (see). Let’s watch again the graph of the fat balance (difference between ingested and oxidized fat) from this study:

As we can see, the first few days the 50% extra calories that are consumed as fat (black dots) are more fattening than when given in the form of carbohydrates (white dots). The two diets do not produce the same outcome, in contrast with what Guyenet says. This is very important, because anyone who hasn’t read this article and listens to Guyenet’s claims, is being deceived. Extra dietary fat makes you fatter than extra carbohydrates, at least in the two weeks of this experiment. And this is clearly stated by the authors of the experiment:

we find that for equivalent amounts of excessive energy, fat produces more accumulation of body fat than carbohydrates.

This is an inconvenient truth for Guyenet’s claims. And he hides this fact. He says that according to the carbohydrate-insulin hypothesis there should have been a difference between groups, and he says there is not. But the truth is that there are differences between groups, differences that refute Guyenet’s hypothesis, which is that the accumulation of body fat is determined by the caloric intake.

This demonstrates that insulin is not what gets fat into fat tissue. Calorie intake is what controls that. Stephan Guyenet, PhD

Guyenet uses this experiment as a refutation of Taubes’ hypothesis, but he hides that the experiment refutes his own hypothesis. It is not the calories in the diet what determines the accumulation of body fat. This experiment is very clear about this.

If we want to understand why people get fat, we can look at studies that overfed people […]

As I said, this is a very interesting part of the debate. And there are many clarifications I want to make. For example, that this type of experiments do not demonstrate that we gain fat because we eat more than we expend, which is Guyenet’s hypothesis. The overeating hypothesis is very complicated to test. How would it be tested? Imagine that we have two groups of participants to whom we give exactly the same food, but each day we give 10 kcal/d extra to one of the groups. As one group gets fatter than the other –if that actually happens— the intake would be adjusted to continue giving those 10 extra kcal/d that make them gain body fat. And, after 5 years, for example, that group would have gained 2.5 kg more than the other group, if the overeating hypothesis is correct. Of course, the experiment would have to be done with all kinds of diets, since checking the result only in one diet would not guarantee the same outcome with a different diet. I assume everybody can see the difficulty of carrying out this experiment with enough participants, for enough time, with enough control of the intake, testing a wide-enough set of diets and with enough control of the levels of physical activity to test this hypothesis. As the test cannot be performed under real conditions, what the overeating experiments do is change the conditions to achieve a much greater effect and much earlier. The experiment that Guyenet cites does something completely different from the situation of interest: they give 1000 or 1500 extra kcal/d each day on top of a specific diet, and, they assume that if that causes body fat accumulation, the mechanism by which people who do not force theirself to eat those extra 1000 kcal/d is the same as in that experiment, regardless of the diet composition. That approach is called the fallacy of a single cause, which is to suppose that when a cause of an effect has been found, that one is the only possible cause for that effect. The reason why a person gets fat when they are not forced to eat exorbitant amounts of food day after day may not have to do with the amount of food, but with its composition. That idea is what Taubes proposes. But that possibility is discarded without any further explanation by the advocates of the energy balance pseudoscience, like Guyenet. We can also interpret this error as a fallacy of continuum: although we do not know at which moment we are going to begin to gain weight “because of the excess” when we progressively increase the amount of food, something that will happen if you force yourself to eat much more than a normal person does, it does not follow that food ingestion in normal amounts and an abnormally high food intake are comparable situations. And these experiments claim that both situations are the same and aim to shed light on how obesity develops. And, as a matter of fact that is the way Guyenet introduces them: “if we want to understand why people get fat, we can look at studies that overfed people”.

The overeating experiments are the ones that can be done, and the ones that researchers can include in their CVs, but not necessarily those that bring light on the nature of obesity. Note, on the other hand, that those experiments do not test Taubes’ hypothesis: they do not change the composition of the food in order to produce a bigger or smaller insulin secretion. As Taubes says, these experiments assume that they are testing what happens naturally in the person who gains body fat. It is not necessarily true. They show that ONE WAY to gain body fat is to force an extreme food intake. One way, not necessarily the only one. This experiments do not show that this is the way in which those of us who do not force ourselves to eat exorbitant amounts of food gain weight.

Note from this experiment we only have fasting insulin data, not postprandial levels. Therefore, it is not possible to talk about relationships between fat accumulation and insulin levels. Guyenet assumes that for the high-carbohydrate extra load the secretion of insulin will be greater than for the high-fat extra load, but he does not know if it is true because that data is not in the article.

Another important aspect of this experiment is the time evolution of the outcome. At the very first days, the extra dietary load in the form of fat is more fattening than the dietary load in the form of carbohydrates, but as the days go by, the oxidation of fat is reduced in the high-carbohydrate-load diet, and after 14 days the two diets are almost equally fattening. What happens in the longer term? It is not tested, and we cannot make it up. In these unreal conditions, in the very short term, we know what happens, but in the long term we don’t know what will happen. We cannot draw conclusions about the effects of a diet from short-duration experiments, even if these experiments are the ones that can perform the best measures (see), because what they measure is irrelevant. The relevant outcome is the effect of a diet when it is followed for years.

Guyenet cites another overfeeding experiment (see), which, when examined in detail, doesn’t seem to prove anything. I analyzed it in a separate post, so the length of the present one was not increased. I just point out that the results in terms of body fat accumulation in that experiment are very unreliable and that Guyenet argues that there are different insulin responses in that experiment, when the authors actually said “no significant differences”. Another inconvenient fact that Guyenet misrepresents.

Hall and Guo’s meta-analysis

Guyenet mentions a meta-analysis by Hall and Guo that concludes that for any practical purpose, a calorie is a calorie.

In other words, for any practical purpose “a calorie is a calorie” when it comes to differences in body fat and energy expenditure between controlled isocaloric diets that differ in the ratio of carbohydrates to fat. Hall and Guo .

We have also seen that meta-analysis in the blog (see). As we have just seen, the effect of a diet changes over time, so I represented the duration of the experiments with the effect on body fat. As we see in the following graph, most of the experiments included in the meta-analysis are less than two weeks long, practically all of them reporting less accumulation of body fat with the diets that have more carbohydrates and less fat:

But, as we see in the graph above, for the experiments of greater duration (around a month and a half) the result is favorable in general to the diets that have less carbohydrates.

Hall and Guo don’t take into account the duration of the experiments, they put all together in a meta-analysis and they conclude that there is not a clear winner, so there is no effect of the diet composition! Well, that’s wrong, the composition does matter. If you follow the Western standard diet, with 50-60% carbohydrates, a sudden increase of dietary fat can cause you to accumulate body fat during the first days after the diet change, an effect that is biiger than if you increase carbohydrates and reduce fat. The composition of the diet does matter. But if you follow a diet for two months, it may be the other way around. If you have the “practical purpose” of living more than two months, this meta-analysis does not rule out the importance of the diet composition. We don’t know what happens in the long term and we can’t make it up.

Again, let’s notice that Guyenet says that this meta-analysis finds no differences between diets: it’s not true, and anyone who listens to him is being deceived. But to say the truth is inconvenient for the pseudoscience he defends. There are differences between diets and that fact refutes his hypothesis that body fat is determined by the calories in the diet . You always have to check the data and trust no one.

Ludwig’s experiment

This experiment is commented in this blog post, and one of the authors describes it here.

What happened with this experiment? The first reaction was to try to discredit the study by stating that the way of calculating the results had changed, because the outcome was not what the researchers wanted.

Is that true? According to David Ludwig (see), the protocol of the experiment was unusually detailed (unlike other experiments, in which the authors don’t give many details and then they do whatever they fancy) and was incorrectly stated. As the experiment progressed, they were fixing mistakes. And, when they realized that the measure of the energy expenditure was wrongly specified: they fixed the mistake. This happened BEFORE BREAKING THE BLIND in the experiment. I say this again: they fixed the mistake before breaking the blind.

The error was recognized and corrected a priori. We obtained IRB approval for our final analysis plan on 06 Sept 2017, before the blind was broken (and indeed, before measurement of the primary outcome had been completed by our collaborator Bill Wong in Houston). Similarly, we corrected the Clinical Trials registry prior to breaking the blind. We provide documentation of this timeline, and additional detail, in the Supplement Protocol section.

This is important: they fixed the error in the protocol without knowing if that correction would benefit one outcome or another. Therefore, to affirm that the protocol was changed because the data did not reflect what they wanted, is defamation. But, of course, the outcome of this experiment was inconvenient for Hall, Guyenet and their friends.

What has Hall done? With the unblinded data, which was provided by the authors of the experiment, he has looked for alternative ways to calculate an outcome so the statistical significance is reduced (see). For example, calculating the effect of different diets not from the moment they start to be different, but from before that, introducing noise in the measure:

image_3641

I refer the interested reader to Petro’s analysis of Hall’s Hall’s jiggery-pokery:

Moreover, Guyenet says that there is dietary intake data for some participants that would violate the first law of thermodynamics, and that if the data from those participants is removed from the calculations the differences between diets disappear. This is not true. In this experiment we have both energy expenditure data and energy intake data, the latter being used as a corroboration of the former, since it is a fact that dietary intake data are inherently unreliable. As I understand it, Kevin Hall (see) decided to redo the analysis of the data by discarding the energy expenditure data of those participants whose energy intake data he thought was erroneous, a very questionable decision, since an error in the energy intake does not invalidate the corresponding energy expenditure data, which may still be correct. Even if the energy intake data is incorrect, the corresponding energy expenditure data is from of a person who maintains their body weight, and that’s what the experiment was about. By making that very debatable —-and convenient for him— reanalysis of the data, as the threshold for data elimination was lowered, the difference between groups was reduced, but the difference between groups was not eliminated as Guyenet claimed in the debate. In Hall’s words:

The intercept of the best fit line was 30 ± 3 kcal/d per 10% reduction in dietary carbohydrates and corresponds to the estimated dietary effect on TEE when all energy is accounted

A TEE increment by 30 kcal/d for every 10% reduction in the percentage of carbohydrates is a huge amount. An effect of that size can perfectly explain the difference between regaining the lost weight and keeping the lost weight. The difference between diets has not disappeared, it has only been reduced by this more than questionable data manipulation by Kevin Hall. Guyenet’s claim that there was no difference between diets is a lie.

It is Hall who has performed an alternative analysis of the data because the outcome of this experiment is inconvenient for the hypotheses on which he has based his career. And he has used unblinded data, knowing exactly what he had to change to achieve the desired result. Accuse the other side of what you are guilty.

Remember these actions by Hall and Guyenet, because later in the debate Guyenet will accuse Taubes of saying that experiments are garbage when they do not support his beliefs:

There is a remarkable correlation between studies undermining your beliefs and you thinking about those studies as garbage. Stephan Guyenet, PhD

Does he talk about Taubes or is he talking about Hall and himself? Huge hypocrisy!

10 kcal/d

Finally, we have the Guyenet’s insult to Taubes, saying that, in his opinion, he doesn’t understand human energetics (n.b. I didn’t know that there are special energetics for humans). Taubes asked him to stop treating him like he was an idiot. And Guyenet’s insult precedes him telling something that everyone knows, which is that when you get fat you usually have an increased energy intake and an increased energy expenditure. Is that what Taubes doesn’t understand? What a clarification from this energy genius named Guyenet.

But let’s not lose sight of Guyenet’s maneuver: as he cannot talk about “excess” in a person who accumulates 10 kcal/d and has still not gained weight, what he does to avoid explaining that situation is to talk about a situation that has nothing to do with it, which is that of a person who is already obese. Then he defines “excess” as the difference between what that person eats and what a lean person eats.  He says that people do not lose weight because they eat more than lean people. That is his belief, but he doesn’t know if it’s because of that or it isn’t. This is just his baseless belief. But he has avoided talking about the fattening process and has made it clear that, in his opinion, if you are overweight, you eat too much and that’s why you don’t lose your extra weight. This is a good trick, but the only thing that shows is his inability to answer Taubes question.

Taubes understands what Guyenet is explaining, but he doesn’t believe that body fat gain is caused by too much energy. And he believes that it is possible to gain weight without an increased intake, something that Guyenet believes is a requirement to gain weight. Guyenet insults him but he is not able to explain why Taubes’ view is wrong.

Go to the conclusions
Go to the fifth part
Go to the fourth part
Go to the third part
Go to the second part
Go to the first part

Debate Taubes-Guyenet. Mi análisis (III)

(English version: click here)

Mis notas sobre el tercer segmento del debate y a continuación mis comentarios:

  • [SG 1h2m] Cuando utilizas métodos precisos, encuentras que las personas con metabolismo mágico, quienes tienen obesidad y no comen mucho, parecen no existir.
  • [SG 1h3m] Quiero hablar sobre estudios en los que aumenta la ingesta de calorías. Queremos entender por qué las personas engordan, podemos ver estudios que sobrealimentaron a las personas con grasas o carbohidratos exclusivamente. En un estudio, se calcularon los requerimientos de energía y luego aumentaron eso en un 50% con grasas o carbohidratos. Este es el estudio de Horton, referencia [16]
  • [SG 1h4m] Si la hipótesis de Gary es correcta, estas personas deberían haber ganado grasa en la sobrealimentación de carbohidratos pero no en la sobrealimentación con grasa. Estas personas estaban en un pabellón metabólico, por lo que los investigadores podían monitorizar todo. Sin trampas. No hay inexactitudes.
  • [SG 1h6m] Lo que encontraron es que al final de un período de 2 semanas de sobrealimentación, el grupo de carbohidratos y grasas ganó exactamente la misma cantidad de grasa corporal. En un segundo estudio hicieron lo mismo y encontraron el mismo resultado. Experimento éste de 3 semanas de duración. Diferentes respuestas de insulina, diferentes cantidades de carbohidratos y grasas, exactamente la misma cantidad de ganancia de grasa. Esto demuestra que la insulina no es lo que mete la grasa en el tejido graso. La ingesta de calorías es lo que controla eso.
  • [GT 1h7m] El paradigma en el que trabajas determina las preguntas que haces. Este experimento presupone que las personas engordan por sobrealimentación. Piensan que están haciendo lo que ocurre naturalmente. Están respondiendo la pregunta de si las personas pueden engordar con la sobrealimentación. Este experimento se basa en el paradigma que quieren someter a prueba.
  • [GT 1h7m] [Comentarios sobre la relación de Peters y Hill con Olestra y la industria azucarera.]
  • [GT 1h10m] 10 kcal/d, que es menos que un bocado de comida, explica la obesidad. ¿Cómo explicamos esas 10 kcal/d? ¿Está el cerebro de alguna manera regulando eso? ¿O se debe a una desregulación en el cuerpo que atrapa la grasa en las células grasas o evita que la grasa se use como combustible? Si alguien bebe 5 cervezas al día, puede que sólo almacene 10-20 kcal/d, ¿cómo sucede eso y por qué va aquí y no aquí? [señala partes del cuerpo]
  • [GT 1h12m] No es tan difícil imaginar que alguien durante una hambruna relativa puede almacenar 10 kcal/d. Si sólo están comiendo 1200, 10 se quedan en las células grasas y 1190 se excretan o se gastan. Nada en las leyes de la física lo dice. En modelos animales se puede encontrar la disociación entre obesidad y comer demasiado.
  • [Joe Rogan] En esencia, estás diciendo que incluso si alguien consume muchas o pocas calorías cada día, 2000 kcal/d, si esas calorías se consumen en forma de azúcar, el cuerpo almacenará parte de ellas, incluso si el cuerpo no recibe suficiente comida, mientras que si consumes proteínas, vegetales, etc., tu cuerpo no hará eso.
  • [GT 1h13m] Esto nos lleva a la pregunta de la evidencia y al mecanismo.
  • [Joe Rogan] Pero estás diciendo eso, ¿cierto? que si dos personas siguen la misma ingesta calórica, una de ellas con 2000 kcal/d de pollo, pescado, verduras y la otra de 2000 kcal/d de batidos y bebidas azucaradas, pasta y BS, esa segunda persona ganará una cierta cantidad de calorías y las acumulará como grasa, independientemente [de las calorías].
  • [GT 1h14m] Sí, esa es la hipótesis. Y esa hipótesis puede ser probada. Stephan cree que ha sido probado 80 veces, yo creo que hicieron un mal trabajo al probarlo. Y ambos tendemos a rechazar los estudios que no nos gustan, cuando definimos “no me gusta” como no tener la respuesta que creemos que es correcta.
  • [Joe Rogan] Pero tú, Stephan, crees que esto no es correcto. Dices que en el estudio donde agregan grasa adicional y carbohidratos adicionales, ambos ganan la misma cantidad de peso.
  • [SG 1h14m] Correcto. Si la hipótesis de Gary es correcta, hay que ver diferentes niveles de ganancia de grasa.
  • [Joe Rogan] ¿Fue un estudio a corto plazo?
  • [SG 1h14m] Sí, fue un estudio a corto plazo. 2 y 3 semanas. Es muy corto. Pero si la insulina es la hormona que pone grasa en las células adiposas, debería ver algún tipo de diferencia, algún tipo de efecto sobre el aumento de grasa.
  • [GT 1h15m] Un problema con los estudios de sobrealimentación es que una de las hipótesis dice que el balance de energía depende del contenido de macronutrientes de los alimentos. Por lo tanto, va a tener un valor diferente según el contenido de macronutrientes.
  • [GT 1h16m] El estudio de Ludwig es un ejemplo. Vieron diferentes niveles de gasto de energía dependiendo del contenido de carbohidratos de la dieta. Cuanto más bajos los carbohidratos, mayor será el gasto de energía.
    [GT 1h18m] Los experimentos deben tener en cuenta todas las hipótesis en competencia. Si hay un efecto umbral de la insulina, como es la realidad, no esperamos ver ninguna diferencia entre los grupos, ya que ambos están en la meseta de la respuesta de la insulina. Si realmente se activa en ambos grupos, ambas hipótesis predicen la misma ganancia de grasa.
  • [GT 1h20m] [Anécdota sobre un amigo obeso]. Mi hipótesis es que habría ganado peso sin importar si comía o no 300 kcal extra por día, porque su insulina estaba elevada.
  • [SG 1h20m] Es fácil contar historias, no es fácil contar historias respaldadas por evidencia científica.
  • [SG 1h20m] 29 estudios han medido el gasto de energía en dietas que difieren en carbohidratos y contenido de grasa. Cuando se juntan todos estos estudios, casi no hay diferencia en la tasa metabólica si las personas comen carbohidratos o grasas. De hecho, la muy pequeña diferencia favorece las dietas altas en carbohidratos.
  • [SG 1h21m] El estudio que dice Gary (de Ludwig) es el que reporta la mayor diferencia entre esos 28+1 estudios.
  • [SG 1h22m] En el estudio de Ludwig, algunos de los datos de participantes son literalmente físicamente imposibles. Si se eliminan los datos claramente erróneos, el estudio ya no reporta un mayor gasto energético en una dieta baja en carbohidratos y es consistente con los 28 estudios anteriores.
    [SG 1h23m] En lo que respecta a las 10 kcal/d, Gary, sigo teniendo la sensación de que no entiendes la energética humana, porque no es así como funciona.
  • [GT 1h23m] Me estás insultando, tienes que dejar de hacer eso. Sigues actuando como si creyeras que soy un idiota.
  • [SG 1h23m] Sólo se necesita una pequeña cantidad de calorías adicionales para hacer que alguien gane grasa. A medida que aumenta la grasa aumentan sus necesidades calóricas.
  • [GT 1h24m] ¿Cómo hace eso el cerebro?
  • [SG 1h24m] No dije que el cerebro hiciera eso. Mi mensaje es que cuando se tiene obesidad, se consume entre un 20 y un 35% más de calorías de las que se consumían cuando se estaba delgado. No es 1 ó 2 botes de coca-cola más al día lo que les permite permanecer obesos, ya que consumen un 20-35% más. No son 10 calorías adicionales.
  • [SG 1h26m] Si consume 10 kcal más de lo que necesita, las almacena.
  • [SG 1h27m] La ingesta de azúcar ha estado disminuyendo en los EEUU durante los últimos 20 años, llegó a su punto máximo en 1999 y ahora es un 15-23% más bajo que en 1999. La obesidad ha aumentado durante los últimos 20 años. Lo mismo en el Reino Unido.
  • [SG 1h29m] El contraargumento de Taubes es que la cantidad de azúcar que consumíamos hace 20 años puede influir en nosotros hoy.
  • [GT 1h30m] Reduciendo de 20 a 17 cigarrillos/día, ¿esperamos ver una reducción en las tasas de cáncer de pulmón?
  • [SG 1h30m] Se esperaría una caída.
  • [GT 1h30m] La pendiente podría reducirse un poco. Si realmente observamos la tasa de crecimiento, la prevalencia parece estar estancada 6 ó 7 años más tarde.
  • [SG 1h30m] Eso no es correcto.
  • [GT 1h31m] También hay un efecto generacional. Cada generación es más susceptible. Eso ha estado sucediendo en los Estados Unidos y en todo el mundo. Los niños de madres obesas y diabéticas tienen un mayor riesgo de ser obesos.

Arrogancia no es lo mismo que asertividad

En este segmento tenemos a Guyenet nuevamente calificando las opiniones de Taubes de historietas, presumiendo de defender una opinión basada en evidencia científica y afirmando que su interlocutor no entiende la energética del cuerpo humano. Insisto en la advertencia de que no confundamos la arrogancia de Guyenet con un síntoma de que tiene razón o de que sabe de lo que habla. La arrogancia sólo es síntoma de arrogancia, nada más. Y no hay que confundir arrogancia con asertividad.

La desinformación de Guyenet sobre el azúcar

Empiezo por el final del segmento. Guyenet cita en el instante 1h27m el dato de que la tasa de obesidad sigue subiendo aunque el consumo de azúcar se ha reducido en los últimos años. El argumento es impropio de una persona con una titulación universitaria, mucho más si hablamos de alguien con un doctorado. Da igual lo arrogante que sea: lo que está soltando es una indiscutible estupidez.

¿Por qué es una estupidez? Está explicado en estas dos entradas:

Hago un resumen. En la siguiente gráfica muestro el consumo anual de azúcar en USA (curva azul) desde 1980 hasta 2015 y el incremento anual en el porcentaje de adultos obesos (curva naranja):

Como vemos, podría haber una relación causal entre consumo de azúcar y peso corporal, pues los cambios en el consumo de azúcar tienen correlación con la tasa a la que crece la obesidad. A mayor consumo de azúcar, crece más deprisa la obesidad. Y la correlación es también llamativa en el caso de las bebidas azucaradas. No es prueba de causa-efecto, pero tampoco permite descartar causa-efecto.

Bueno, pues Guyenet, ¡¡que tiene un doctorado!!, lo que hace es suponer que tiene que haber una relación directa entre consumo de azúcar (curva azul) y la integral de la curva naranja, es decir, el valor acumulado, algo que no tiene ningún sentido si se supone que el azúcar es engordante, que es la hipótesis que quiere refutar. Si simplemente hubiese representado los datos de otra forma, como hemos visto en la gráfica anterior, habría visto esa relación que cree que no existe.

pastedimage

Y como no encuentra la relación directa donde nadie espera que la haya, da por supuesto que el azúcar no puede ser un factor importante en la epidemia de obesidad. Al margen de que eso sea verdad o no, al margen de cuál sea el papel del azúcar en la epidemia de obesidad, el argumento de Guyenet es manifiestamente erróneo. Si alguien quiere una explicación más detallada del gravísimo error de Guyenet, la tiene en las dos entradas que he citado antes.

No confundamos arrogancia con competencia.

Falacia de falsa dicotomía

[SG 1h6m] Esto demuestra que la insulina no es lo que mete la grasa en el tejido graso. La ingesta de calorías es lo que controla eso.

Aunque fuera cierto lo que Guyenet afirma, de eso no se deduciría que son las calorías las que determinan si hay acumulación de grasa corporal. Guyenet está empleando la falacia de falsa dicotomía. Su afirmación de que son las calorías las que controlan la acumulación de grasa corporal debe ser demostrada.

Los argumentos de Taubes

Como alguno de los argumentos de Taubes me parecen reseñables, los repito aquí:

  • 10 kcal/d, que es menos que un bocado de comida, explica la obesidad. ¿Cómo explicamos esas 10 kcal/d?
  • No es tan difícil imaginar que alguien durante una hambruna relativa puede almacenar 10 kcal/d. Si sólo están comiendo 1200 kcal/d, 10 se quedan en las células grasas y 1190 se excretan o se gastan.
  • En modelos animales se puede encontrar la disociación entre obesidad y comer demasiado.

El primer argumento Guyenet lo elude, como analizaré más adelante. Del segundo dice que no se puede engordar sin comer de más. Y, sobre el tercero, es una realidad que hemos visto en el blog que en los experimentos con animales se demuestra que se puede engordar sin que exista una ingesta aumentada. ¿Cómo puede justificar Guyenet su irracional creencia en que la sobrealimentación es un requisito para engordar en humanos? 

Experimentos de sobrealimentación

Ésta es una de las partes más interesantes del debate. Guyenet empieza citando el experimento de Horton et al. 1995. Experimento de sobrealimentación en el que se da comida extra en forma de grasa o en forma de carbohidratos. Y Guyenet dice, textualmente, que si la hipótesis carbohidratos-insulina fuese correcta, tendrían que verse diferencias entre dietas, y dice que no se ven: misma ganancia de grasa en ambos grupos, afirma.

Este experimento ya lo hemos visto en el blog (ver). Recordemos la gráfica del balance de grasa (diferencia entre grasa ingerida y grasa oxidada) que nos da ese estudio:

Como vemos, los primeros días el 50% extra de calorías que se da en forma de grasa (puntos negros) es más engordante que si se da en forma de carbohidratos (puntos blancos). Las dos dietas no producen el mismo resultado, a diferencia de lo que afirma Guyenet. Esto es muy importante, porque alguien que no conozca este experimento y simplemente escuche a Guyenet, está siendo engañado. La grasa dietética extra engorda más que los carbohidratos extra, al menos durante las dos semanas del experimento. Y así lo reconocen los autores del experimento:

encontramos que para cantidades equivalentes de energía excesiva, la grasa produce más acumulación de grasa corporal que los carbohidratos.

Pero para el argumento de Guyenet, ésta es una realidad inconveniente, y la oculta. Él dice que según la hipótesis carbohidratos-insulina debería haber diferencias entre grupos, y dice que no las hay. Pero la verdad es que sí hay diferencias entre grupos, lo que demuestra falsa la hipótesis de Guyenet, que es que la acumulación de grasa corporal la marcan las calorías ingeridas.

La ingesta de calorías es lo que controla eso.

Guyenet usa el experimento para hacer creer que éste refuta la hipótesis de Taubes, pero oculta que el experimento refuta su propia hipótesis. No son las calorías de la dieta las que determinan la acumulación de grasa corporal, y eso el experimento lo deja clarísimo.

Queremos entender por qué las personas engordan, podemos ver estudios que sobrealimentaron…

Como digo, es una parte muy interesante del debate. Y hay muchas aclaraciones que hacer. Por ejemplo, que en este tipo de experimentos no se está demostrando que engordemos porque comamos más de la cuenta, que es la hipótesis de Guyenet. La hipótesis del sobreconsumo es muy complicada de someter a prueba. ¿Cómo se haría? Imaginemos que tenemos dos grupos de participantes a los que damos exactamente la misma comida, pero cada día damos 10 kcal/d extra a uno de los grupos. Conforme vaya engordando un grupo más que el otro —si es que eso sucede, lo que es mucho suponer—, se ajustaría la ingesta para seguir dando esas 10 kcal/d extra que hacen engordar. Y, al cabo de 5 años, por ejemplo, ese grupo pesaría 2.5 kg más que el otro, si la hipótesis es correcta. Por supuesto, el experimento habría que hacerlo con todo tipo de dietas, pues comprobar el resultado sólo en una no garantizaría que el resultado fuera el mismo con una composición diferente. Supongo que vemos la dificultad de realizar este experimento con suficientes participantes, suficiente duración, suficiente control de la ingesta, suficiente abanico de dietas y suficiente control de los niveles de actividad física para testear esta hipótesis. Pues bien, como la situación real no se puede someter a prueba, lo que hacen los experimentos de sobrealimentación es extremar las condiciones para conseguir un efecto mucho mayor y mucho antes. Lo que se hace en el experimento que cita Guyenet es algo completamente diferente de la situación de interés: dan 1000 ó 1500 kcal/d extra cada día sobre la base de una dieta concreta, y, asumen, porque sí, que si eso causa acumulación de grasa corporal, el mecanismo por el que se produce acumulación en una persona que no fuerza a comer esas 1000 kcal extra cada día es el mismo que en ese experimento, al margen de la dieta que siga. Ese planteamiento se llama falacia de causa única, que es suponer que encontrada una causa de un efecto, ésa es la única causa posible para ese efecto. La causa por la que una persona engorda cuando no se fuerza a comer cantidades desorbitadas día tras día puede no tener que ver con la cantidad de comida, sino con la composición de la misma. Eso es lo que propone Taubes. Pero esa posibilidad es descartada sin más por los defensores de la pseudociencia del balance energético, como es el caso de Guyenet. También podemos interpretar este error como una falacia de continuum: aunque no sepamos en qué momento vamos a empezar a engordar “por culpa del exceso”, algo que sucederá si te fuerzas a comer mucho más de lo normal, de eso no se deduce que la ingesta normal de comida y la ingesta anormalmente excesiva de comida sean situaciones comparables. Y estos experimentos pretenden que ambas situaciones son lo mismo y pretenden arrojar luz sobre cómo se desarrolla la obesidad. De hecho, así es cómo Guyenet los introduce en el debate: “si queremos entender por qué engordamos, hablemos de experimentos de sobrealimentación”.

Los experimentos de sobrealimentación son los que se pueden hacer, y los que permiten llenar el CV a los investigadores, no necesariamente los que arrojan luz sobre la naturaleza de la obesidad. Nótese por otro lado cómo esos experimentos no someten a test la hipótesis de Taubes: no alteran la composición de la comida para producir una mayor o menor secreción de insulina. Como dice Taubes, estos experimentos asumen que están poniendo a prueba lo que sucede de forma natural en quien engorda. No es verdad que sea así. Demuestran que UNA FORMA de engordar es forzar la ingesta de forma anormal. Una forma, no necesariamente la única. No demuestran que ésa sea la forma en la que engordamos quienes no nos empeñamos en comer en cantidades desorbitadas.

Nótese que en este experimento sólo nos dan datos de insulina en ayunas, no niveles postprandiales, con lo que es imposible establecer relaciones entre acumulación de grasa y niveles de insulina. Guyenet da por supuesto que con la carga de carbohidratos la secreción de insulina va a ser mayor, pero no lo sabe pues ese dato no está en el artículo.

Otro aspecto importante de este experimento es el factor tiempo. Al principio, la carga dietética extra en forma de grasa es más engordante que la carga dietética extra en forma de carbohidratos, pero conforme pasan los días la oxidación de grasa se va reduciendo en la dieta con carga de carbohidratos, y al cabo de 14 días las dos dietas son casi igual de engordantes. ¿Y a más largo plazo? No se sabe, y no nos lo podemos inventar. En estas condiciones irreales, a muy corto plazo, sucede lo que estamos viendo, y a largo plazo no sabemos qué sucederá. No podemos sacar conclusiones sobre los efectos de una dieta a partir de experimentos de tan corta duración, aunque sean los que mejor miden las cosas (ver), porque la medida que hacen es irrelevante para lo que interesa, que es el efecto de una dieta mantenida años.

Guyenet cita otro experimento de sobrealimentación (ver), que, mirado en detalle deja grandes dudas sobre en qué medida se puede usar para demostrar nada. Lo comenté en una entrada aparte, para no alargar ésta. Sólo resalto que los resultados en términos de acumulación de grasa corporal en ese experimento son muy poco fiables y que Guyenet argumenta que hay diferentes respuestas de insulina en ese experimento, cuando los autores en realidad dijeron “sin diferencias significativas”. Otro dato inconveniente que Guyenet tergiversa.

El metaanálisis de Hall y Guo

Guyenet hace mención de un metaanálisis de Hall y Guo que concluye que para cualquier propósito práctico, una caloría es una caloría.

En otras palabras, para cualquier propósito práctico “una caloría es una caloría” cuando se trata de diferencias en grasa corporal y gasto energético entre dietas isocalóricas controladas que se diferencian en el ratio de carbohidratos a grasa. Hall y Guo.

También hemos visto ese metaanálisis en el blog (ver). Como acabamos de ver, el efecto de la dieta varía con el tiempo, así que me entretuve comparando la duración de los experimentos con el efecto en la grasa corporal. Como vemos en la siguiente gráfica, la mayoría de experimentos incluidos en el metaanálisis son de menos de dos semanas de duración, prácticamente todos ellos reportando menos acumulación de grasa corporal con la dieta que tiene más carbohidratos y menos grasa:

Pero, como vemos en la gráfica, para los experimentos de mayor duración (mes y medio) el resultado es favorable en general a las dietas que menos carbohidratos tienen.

Hall y Guo no tienen en cuenta la duración de los experimentos, los juntan todos sin más en un metaanálisis y concluyen que unos van para un lado y otros para otro, así que ¡¡todo da lo mismo!! Pues no, no da lo mismo. Si sigues la dieta estándar occidental, con un 50-60% de carbohidratos, aumentar bruscamente la grasa dietética te puede hacer acumular grasa corporal los primeros días tras el cambio de dieta, más que si aumentas los carbohidratos y reduces la grasa. No da lo mismo la composición de la dieta. Pero si la dieta la mantienes dos meses, puede que sea al contrario. Si tienes el “propósito práctico” de vivir más de dos meses, este metaanálisis no permite descartar la importancia de la composición de la dieta. No sabemos qué pasa a largo plazo y no nos lo podemos inventar.

Nuevamente, fijémonos en que Guyenet dice que este metaanálisis no encuentra diferencias entre dietas: no es cierto, y cualquiera que le escuche está siendo engañado. Pero reconocer lo contrario es inconveniente para la pseudociencia que él defiende. Sí se encuentran diferencias entre dietas y eso refuta su hipótesis de que la grasa corporal es determinada por las calorías de la dieta. Hay que mirar los datos siempre, sin fiarse de nadie.

El experimento de Ludwig

Este experimento está comentado en esta entrada del blog, y uno de los autores lo describe aquí.

¿Qué ha pasado con este experimento? Lo primero fue intentar desacreditar el estudio afirmando que se había cambiado la forma de calcular los resultados, porque no salía lo que los investigadores querían.

¿Fue así? Según Ludwig (ver), el protocolo a seguir era inusualmente detallado (a diferencia de otros experimentos, en los que no detallan nada y luego hacen lo que les conviene) y estaba incorrectamente establecido. Conforme avanzaba el experimento, los autores fueron corrigiendo cosas. Y, llegado el momento, se dieron cuenta de que la medida del cambio en el gasto energético estaba mal especificada: corrigieron el error ANTES DE QUITAR EL CIEGO del experimento. Repito: cambiaron el protocolo antes de quitar el ciego.

The error was recognized and corrected a priori. We obtained IRB approval for our final analysis plan on 06 Sept 2017, before the blind was broken (and indeed, before measurement of the primary outcome had been completed by our collaborator Bill Wong in Houston). Similarly, we corrected the Clinical Trials registry prior to breaking the blind. We provide documentation of this timeline, and additional detail, in the Supplement Protocol section.

El error fue reconocido y corregido a priori. Obtuvimos la aprobación del IRB para nuestro plan de análisis final el 6 de septiembre de 2017, antes de que se rompiera el ciego (y de hecho, antes de que nuestro colaborador Bill Wong en Houston completara la medición del resultado primario). Del mismo modo, corregimos el Registro de Ensayos Clínicos antes de romper el ciego. Proporcionamos documentación de la secuencia temporal de hechos y detalles adicionales en la sección Suplemento Protocolo.

Esto es importante: corrigieron el error sin saber si esa corrección beneficiaba un resultado u otro. Por tanto, afirmar que se cambió el protocolo porque los datos no reflejaban lo que se quería, es sencillamente difamar. Pero, claro, el resultado era inconveniente para Hall, Guyenet y compañía.

¿Qué ha hecho Hall? Pues con los datos en abierto, ¡¡ya sin ciego!!, proporcionados por los propios autores del experimento, buscar formas alternativas de calcular un resultado que reduzcan la significancia estadística (ver). Por ejemplo, calculando el efecto de las diferentes dietas no desde el momento en que empiezan a ser diferentes, sino desde tiempo antes, introduciendo ruido en la medida:

imagen_3641

Sobre esto último, remito al lector interesado al análisis de Petro de los trucos de birlibirloque de Hall:

Por otro lado, Guyenet dice que hay datos de ingesta de los participantes que no cuadran porque violarían la primera ley de la termodinámica, y que si se eliminan de los cálculos desaparecen las diferencias entre dietas. No es cierto. En este experimento se dieron medidas tanto de gasto energético como de ingesta energética, estas últimas como corroboración de las primeras, pues son inherentemente poco fiables. Lo que yo entiendo es que Kevin Hall (ver) decidió rehacer el análisis de los datos descartando los datos de gasto energético de aquellos participantes cuyos datos de ingesta energética fueran sospechosos de ser muy erróneos, una decisión muy discutible, pues un error en la ingesta energética no invalida los datos de gasto energético, que pueden seguir siendo correctos. Aunque el dato de ingesta energética sea incorrecto, ese gasto energético es el de una persona que mantiene el peso corporal, y de eso iba el experimento. Al hacer ese muy discutible —y conveniente para él— reanálisis de los datos, conforme se reducía el listón de eliminación de datos, se reducía la diferencia entre grupos, pero no se eliminó la diferencia entre grupos como afirma Guyenet en el debate. En palabras de Hall:

The intercept of the best fit line was 30±3 kcal/d per 10% reduction in dietary carbohydrates and corresponds to the estimated diet effect on TEE when all energy is accounted

30 kcal/d más de gasto energético por cada 10% de reducción en el porcentaje de carbohidratos es una magnitud enorme. Esa magnitud puede explicar perfectamente la diferencia entre recuperar el peso perdido y no recuperarlo. No ha desaparecido la diferencia entre dietas, sólo se ha reducido en esta más que discutible maniobra manipuladora de datos de Kevin Hall. La afirmación de Guyenet de que no había diferencia entre dietas era una mentira.

Es decir, es Hall el que ha hecho un análisis alternativo de los datos porque el resultado es inconveniente para las hipótesis en las que ha basado su carrera. Y lo ha hecho sin ciego, sabiendo exactamente qué tenía que cambiar para conseguir el resultado deseado. Ya se sabe: acusa a la otra parte de aquello de lo que eres culpable.

Recordemos estas maniobras de Hall y Guyenet, porque más adelante en el debate Guyenet acusará a Taubes de calificar los experimentos como basura cuando son contrarios a sus creencias:

There is a remarkable correlation between studies undermining your beliefs and you thinking those studies are garbage. Stephan Guyenet, PhD

Existe una notable correlación entre los estudios que socavan tus creencias y que creas que esos estudios son basura.

¿Habla de Taubes o hace referencia a sí mismo y a Hall? ¡Cuánta hipocresía!

Las 10 kcal/d

Para acabar, tenemos el insulto de Guyenet a Taubes diciéndole que en su opinión no entiende la energética humana (n.b. yo no sabía que había una energética especial para humanos). Taubes le pidió que dejara de tratarle como si fuera idiota. Y el insulto de Guyenet sucede como preámbulo a contar algo que sabe todo el mundo, que es que cuando engordas normalmente tienes una ingesta energética aumentada y un gasto energético aumentado. ¿Eso es lo que Taubes no entiende? Menuda aclaración de este genio de la energía que es Guyenet.

Pero no perdamos de vista la maniobra de Guyenet: como no puede hablar de “exceso” en una persona que acumula 10 kcal/d y que todavía no ha engordado, lo que hace es eludir dar una explicación a esa situación e irse a un caso que nada tiene que ver, que es el de una persona ya obesa. Y ahí hace referencia como “exceso” a la diferencia entre lo que se come en ese caso, respecto de esa persona cuando era delgada. Y dice que no adelgazas porque comes más que cuando eras delgado. Cree que es así, pero no sabe si es por eso o no, son sólo sus creencias sin fundamento, pero en todo caso ha evitado hablar del proceso de engordar y ha dejado claro que para él si tienes exceso de peso, comes de más y por eso no adelgazas. Buena maniobra de evasión, pero lo único que demuestra es su incapacidad para dar respuesta a la pregunta de Taubes.

No es que Taubes no entienda, es que Taubes no cree que la acumulación de grasa corporal la produzca un exceso de energía. Y cree que es posible engordar sin una ingesta aumentada, algo que Guyenet considera requisito para engordar. Guyenet le insulta pero no es capaz de argumentar que la visión de Taubes sea errónea.

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Taubes-Guyenet debate. My analysis (II)

(Versión en español: hacer click aquí)

My notes from the second segment of the debate (second half hour of it) and my comments below the notes:

  • [SG 29m] The brain actually regulates body fatness. No one should be surprised by this.
  • [GT 30m] One of the problems is “intellectual phase-lock” [a condition in which dogmatic beliefs prevent certain questions from being asked]. The obesity research community left out of its research endocronilogy in the 1960s, i.e. the hormonal/metabolic regulation of body fatness, oxidation, etc. Everything they have done since has been interpreted incorrectly. Leptin is a good example. They assumed what leptin does is control the brain, but perhaps a lot of what leptin does is done in the periphery. In the search for genes associated with body type all the genes act below the neck (insulin-regulated genes), but with excess body fat they decided they are in the head. The question is that when they look, they are programmed to think body fat is caused by overeating, so they look in the brain.  
  • [SG 35m] They don’t start with any assumption.
  • [GT 36m] Genes can have different jobs in different cells of the body, but if you think that the problem is in the brain, that’s where you look. 
  • [GT 36m] Stephan’s book is supposed to be about obesity, but in fact you never mention anything about the hormonal regulation of fat accumulation. It is just not there and it has to be there. [we can hear the laughter of Guyenet while Taubes speaks] 
  • [GT 37m] Stephan is the defender of the orthodoxy, and I’m the one who comes along and says “you have psychologists and psychiatrists running the field, while endocrinologists solved it”. 
  • [GT 37m] What has the brain to say about the fact that body fat accumulates in some parts of the body and not in others? [Again we can hear Guyenet laughing while Taubes speaks] 
  • [SG 38m] When looking at the genes associated with total body fatness, the thing that causes obesity, genes related to the brain pop up, whereas when looking for genes related to the body fat distribution, we see insulin-related genes, for example in the people who have body fat around their waist.
  • [SG 39m] [sarcasm about Taubes talking about leptin] “this is good”, because he does not normally mention leptin. Researchers do not talk about the peripheral actions of leptin because it has been shown that the effects of leptin are via the brain, not because they wear blinders . [Guyenet taks about himself as a researcher: “WE focus”]. In the experiments in which the leptin receptors are knocked-out in the brain or in the hypothalamus you get obesity, which shows that the brain is a key site of action.
  • [GT 40m] A key site of action. 
  • [SG 41m] The brain is this site of action that causes this to happen. We understand very well how leptin works. People with obesity don’t lose fat because they have a higher set point in their adipostat. When a person loses weight there is a reaction in the brain circuits that regulate body fatness that drives an increase in their cravings and hunger. It does that until the fat comes back. Body fat is regulated by a negatively feedback loop that is controlled by leptin.
  • [Joe Rogan 44m] When you are eating a sugary diet, a high-calorie diet, your body will get fatter, right? 
  • [SG 44m] It depends on how many calories you are eating.
  • [GT 44m] Leptin is not only produced in response to the size of the adipocyte, but also in response to the entry of glucose into the adipocyte, which is partly mediated by insulin. 
  • [GT 45m] Everything that is said has two interpretations, depending on which paradigm you are looking at. And the paradigms are essentially different. 
  • [GT 46m] 8 years ago Stephan and I first fell out when I acted inappropriately in the Ancestral Health Symposium. 
  • [GT 46m] Knowing that more people are entering a room than leaving does not tell us why the room is getting crowded. In obesity, why you are getting fatter has been left out and people decided that overeating was somehow an explanation. 
  • [GT 47m] To know what is the influence of the environment on obesity we must ask ourselves if  we can find an epidemic of obesity without this “modern food environment”. And I found out about the Pima in 1902: poor, malnourished, suffering through famine for 40 years, and yet the women of the tribe, who do all the hard work, were obese. We can then disassociate obesity from the “modern food environment” and the ultra-processed foods. We have obesity despite the existence of famine. [We hear Guyenet laughs]
  • [Joe Rogan 48m] What was the cause of the women becoming obese?
  • [GT 48m] They were “reservationized” and they began eating western foods. You can find the same in the Sioux.
  • [GT 49m] Any population transitions to a Western diet or western diet/lifestyle become obese and develop metabolic syndrome. Genetics aren’t that important thing, the important thing is what’s triggering it in the environment. I think it is certain foods. 
  • [GT 50m] Double burden of obesity: we have obese mothers with malnourished children. And this occurs in populations that have not been able to “overeat”. And if they could have eaten more, why are their children starving? How do we explain obesity in the mothers without assuming that the mothers are overeating? 
  • [Joe Rogan 51m] Stephan, are there populations in the world that are obese and that are not consuming a Western diet, that are not eating sugary products? 
  • [SG 51m] Probably not, because once you have an industrialized food system that is going to include sugar. But there are populations that eat a lot of sugar and are not obese.
  • [SG 52m] Gary has told a story, his version of the Pima story. Let me tell you the version of the story that appears in the scientific literature. They were a society that depended on agriculture, but with the arrival of farmers (settlers of european descent) the river that supplied them was diverted and the government began to provide them with food: calorie dense refined foods, flour, lard and sugar. And they became very obese. Other Pima who, right accross the border, maintained their traditional high-carbohydrate and agricultural lifestyle, were much leaner and healthier.
  • [SG 54m] Gary, you seem to believe that people can gain weight even if they are eating too few calories …
  • [GT 54m] Yes 
  • [SG 54m] These are very casual observations, story-telling. When you look at the data, what you see obese people consume between 20 and 35% higher than people who are lean. Those data come from the most accurate methods that we have. Gary’s model says that is a consequence, a result, of gaining weight, while my model says that that is actually required for the fattening effect to occur. What happens if you reduce the calorie intake by that same amount? It does not matter if you do it by restricting carbohydrates or fat, these experiments have been done, they lose weight.
  • [Joe Rogan 56m] You’re saying that by consuming low amounts of calories but high amounts of sugar, it does not make sense that one can become obese that way. 
  • [SG 56m] Right.
  • [GT 56m] We can find cases where there is obesity without excess food, such as Trinidad in the 1960s. Two thirds of adult women were obese, and there was famine, malnutrition and stunted children. Data say that they consumed fewer calories than those recommended by the WHO for a healthy diet. The brain hypothesis does not explain why a mother is obese while her children are starving. If she has to eat superfluous calories to get fat, which is what that hypothesis says, why isn’t she giving those calories to her children? My hypothesis is that the explanation is that it is the macronutrient content of the diet what triggers obesity. 
  • [GT 59m] There are experiments on which the animals get fat even if they are starving. 
  • [SG 59m] They are experiments done on animals with mutations related to leptin.
  • [GT 59m] The point is that if my body accumulates fat at intake levels at which a thin person can’t, I will gain fat eating the same amount. 
  • [SG 59m] The caloric intake data for Trinidad are not reliable. There is no reason to believe that people were eating 1800 kcal/d and becoming obese. Accurate measures of caloric intake from people who say that they are consuming 1200 kcal / d, say that they consume more calories than thin people. What Gary says is only observed when inferior methods are used to measure calorie intake.
  • [GT 1h1m] I insist on my question: obese mother with starving children. The existence of the starving children strongly suggests that there is not a lot of food available. And we have to explain the obesity in the mother. 
  • [SG 1h1m] There are many reasons why a child may have malnutrition in a non-industrial situations. I don’t have an explanation but it is not necessarily for the reason that Taubes says.

It depends on how many calories you are eating

Guyenet, PhD, the same guy who just a few minutes earlier said that a diet with fat and sugar produced effects that cannot be completely replicated with only sugar or only fat, now worships the energy-balance dogma:

  • [Joe Rogan 44m] When you are eating a sugary diet, a high-calorie diet, your body will get fatter, right? 
  • [SG 44m] It depends on how many calories you are eating.

This is the same guy who believes that sugar can make you fat because it is palatable, regardless of how many calories it has. But when he is interested in showing support to the official dogmas, then he says that calories are what makes us gain fat. Guyenet is a master of cognitive dissonance. Or a master of decepcion who is betting to two horses at the same time.

There is no obesity if westernized food is not present

They both agree on that. It is clear, I would add, that it is not a dysfunction in the brain what causes obesity. An analogy can make this clear: if I prick someone with a needle and that person bleeds, the cause of the bleeding is not the lack of a band-aid: it’s been the needle prick what has caused the bleeding. Even if we know that a band-aid stops the bleeding. Speaking of obesity, if your genetic endowment is better than that from other people, maybe it protects you from “food” that you shouldn’t be eating, but what causes obesity in those other people is the insult, not their faulty brain: the cause is the stimulus, that is, what they are eating and they shouldn’t be eating.

Let’s see an example. Suppose we have two people (person A and person B) who are exposed to two different environmental conditions (conditions 1 and 2) for a time, with the following results in terms of body weight gain:

Person \ Environment  1 two
A 0 kg +6 kg
B 0 kg +7 kg

Even if we found a relationship between genetics and weight gain that explained the difference between those +6 and +7 kg, what is the real cause of the weight gain in this example? It is only an example, but it makes clear that although the differences between people’s fat mass under environment #2 can have a genetic explanation, not necessarily that fact tells us anything meaningful about the actual cause of their obesity.

On the other hand, Guyenet argues that there are populations that consume a lot of sugar and they are not obese. He will give details later in the debate. What I want to emphasize is that his counterargument does not prove anything about the reasons why we get fat in the western world, not even in case we believe the data of those populations are reliable. They just don’t live under the same conditions we do. For example, there could be a synergistic effect of sugar with seed oils (high omega-6) or with some endocrine disruptor, and finding out a population that has a high consumption of sugar and no obesity, in the absence of other factors typical of the western world, cannot be used to exonerate sugar in societies in which sugar coexists with a different set of dietary and environmental factors. Or maybe these people spend a lot of time outdoors (under the sun) and respect their circadian rhythms and that fact protects them in a certain way from sugar, and that is not our case. Or maybe those populations follow very low-fat diets in which sugar is not so harmful to their health. Who knows.

Obese mothers and undernourished children

The “double burden of obesity” is the coexistence of obesity and undernutrition in a population (see). For example, in the following graph we have BMI (body mass index) versus age in refugee camps in Western Sahara. As we can see, in all ages there are both people with clear obesity and people with very low BMI:

And in this study in a quarter of the households coexist obesity and malnutrition:

Our results demonstrate that both stunting (in children and women) and obesity (in women) are highly prevalent among Sahrawi refugees, with central obesity being even more prevalent and appearing at a younger age in women than obesity. Second, more households were affected by overweight and central obesity than by under-nutrition, although the latter affected over one-third of households. Third, an important proportion of refugee households, one in four, are affected by the double burden of malnutrition.

How do you explain that there is an obese mother who has an undernourished child? Guyenet puts into question the data provided by Taubes, that is, he says that a woman cannot gain weight by consuming only 1800 kcal/d.

[SG 1h0m] What Gary says is only observed when inferior methods are used to measure calorie intake

Is that so? Does the obese mother overeat while her child is starving? This is hard to believe.

[Joe Rogan 56m] You’re saying that by consuming low amounts of calories but high amounts of sugar, it does not make sense that one can become obese that way. 
[SG 56m] Correct.

Let’s mention four scientific experiments I have already commented in the blog. In the first one (see), we have a group of rats, the HS group that consumes a diet high in sugar. As we can see in the table below these lines, this groups consumes about 100 kcal/d, while the HF group consumes about 200 kcal/d. The body weight and body fat data tell us that the group that consumes 100 kcal/d finishes the experiment with more weight and more fat mass than the one that consumes 200 kcal/d. Can you get fat while eating too little? Yes, you can.

This is an experiment in animals and, therefore, absolutely controlled. There are no reasons to doubt caloric intake data in animal experiments.

The second experiment (see) shows that the same food, and therefore with the same calories, is much more fattening when consumed as powder than when consumed as pellets. The graph shows in pale pink the evolution of the body weight of three dietary groups that consume much fewer calories than the group represented with empty circles, and yet, the evolution of their body weight is practically the same as in that group:

This means that in this experiment, while eating much less food, those three groups of rats are gaining weight at the same rate as rats that consume more calories. I insist: in the experiments with animals the caloric intake is not poorly measured. The trick of questioning the reliability of the caloric intake is unwarranted here.

In the third experiment ( see ) the group of mice that eats the lowest amount of calories (white points) is the one that gains more weight and more body fat:

In the fourth experiment (see), the diet of the rats is identical in terms of nutrients and calories, differing only in their glycemic index. To prevent rats in the high-glycemic-index diet from gaining more weight than the other group, their intake had to be considerably reduced, as shown in the graph a the top:

Despite the reduced intake compared to the other group and despite having practically the same weight as they have, the high-glycemic group finished the experiment with 71% more body fat: 98 g vs 57 g. And they are eating less food:

[SG 54m] Gary, you seem to believe that people can gain weight even if they are eating too few calories …

Gary Taubes believes that it is possible what the  four scientific experiments above show is possible. The question is why Guyenet doesn’t think it is possible. Doesn’t Guyenet know what has been published in the scientific literature?

Anyway, I think Guyenet is entitled to doubt the data. What is unacceptable is the arrogance of saying that Taubes’ arguments are story-telling and of presuming that his own opinion is supported by scientific evidence.

Gary has told a story, his version of the Pima story. Let me tell you the version of the story that appears in the scientific literature.

As we will see in other segments of the debate, the “anecdotes” that Guyenet will use (the Kuna, the Cuban economic crisis or the Hadza) are observations that are quite similar to the cases explained by Taubes, i.e. the Pima, the Sioux and Trinidad. Story-telling or science in both cases, no matter who puts them on the table. Guyenet uses plenty of derogatory comments towards the Taubes’ arguments and presumes of being the defender of what the scientific evidence says. Why does Guyenet think he is better than Taubes? He is not even a researcher any more, in contrast with what he implies in the debate: he is a writer and a scientific consultant. Not only does he use the fallacy of authority, he does it by bragging about being what he isn’t.

People who suffer from obesity eat too much

I put together here three of Guyenet’s arguments:

  • obese people eat between 20 and 35% more calories than lean people
  • in the Guyenet model eating a lot is a requirement to gain weight
  • if you reduce the intake in that same amount it does not matter if you do it by restricting carbohydrates or fat, the experiments say that you lose weight

The first point already appeared in the first segment, but I insist on it because I find it interesting. Gary Taubes argues in the debate that to develop obesity it is enough to accumulate 10 kcal/d, and that this is not explained by an “excessive” consumption, because of that “excessive” intake that there may be every day only 10 kcal/d end up being storead as body fat. As Guyenet cannot justify saying 10 ridiculous kcal/d are an “excess”, what he does is redefine “excess” as the difference between what you eat when you are already obese and what a lean person eats. With this trick he converts those 10 kcal into a much larger amount, and this allows him to go on using the term “excess”. In any case it is a rhetorical trick that he uses to avoid answering the question. And in doing so, he blames the victim for his weight problem: if you have obesity Guyenet says that you overeat even if you maintain your weight, even if you eat what your body asks or needs to function. We should not fall in his trap: we are not talking about the person who already has excess weight: the one who is gaining weight does so at a rate of 10 kcal/d. Does this accumulation of energy occur because this person eats 10 excess kcal/d compared to the person who does not gain fat? That is the question that Guyenet avoids to answer. Because nobody can accept that 10 kcal/d are an “excess”. And maybe that fat accumulation is not produced by the “excess”, but instead by the composition of the diet. Guyenet has beliefs, but he may be wrong in his beliefs.

Moreover, Guyenet uses this argument as an explanation for the “dual burden of obesity”, but he is not using data from the populations cited by Taubes. He doesn’t know if that is the case of those populations.

The second argument is that an increased intake is a requirement to gain weight in Guyenet’s obesity model. Well, we have seen four scientific experiments that show that, in such a case, his model is wrong. And I find it very interesting that he uses the term “requirement”, because precisely one of the errors on which his pseudoscience is based is to assume that an increased intake with respect to the energy expenditure is a requirement to gain weight. It is not!! That belief is based on errors of reasoning, and I have explained thousands of times in the blog (and we are near the point where saying a thousand times is not an exaggeration): see, seeseesee.

Finally, Guyenet says that by reducing the caloric intake people lose weight. Guyenet is deceiving the hundreds of thousands of people who have seen this debate.The scientific experiments show that people lose weight in the short term, but the lost weight is almost always regained in the long term, even when the energy restriction is maintained (see, see). That’s what the scientific evidence shows, not what Guyenet is telling. What’s more, he could ask Kevin Hall, PhD what happens when you try to make someone lose weight by applying that method (seesee). But hey, it’s no surprise that Guyenet deceives people with clearly wrong arguments. This has an explanation: this guy is Guyenet, PhD.

In regard to this, let’s remember an experiment (see , see) in which a group of mice is forced to eat only 66% of the calories consumed by the rest of the mice (who follow different diets). As we can see, after the initial drop in their body weight they gain weight.

Have those mice lost adherence to the caloric restriction? No. They have gained weight while eating a small amount of food.

NOTE: all the terminology of the energy paradigm is in question. It is not obvious that the term “excess” (or “caloric excess”) can be used associated to body fat gain .

Go to the conclusions
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