(versión en español: pinchar aquí)

Spanish health authorities, when talking about «fad diets», say that «ketone creation is dangerous when it is prolonged in time«. They also say that ketosis is a «dangerous metabolism disturbance«.

They criticize the pollution that comes from the low-carb car and they don’t realise that the high-carb car doesn’t create pollutants because it doesn’t even have an engine. Moreover, it’s a lie: the low-carb car does not contaminate. Ketones are not dangerous.

I am an engineer, not a physician, so may be my approach is wrong… Nevertheless, I ask. Is it possible to lose weight without raising the ketone or triglycerides levels in your blood? Is the «official diet» able to do that? If ketones are not created, where do the fatty acids end up when you burn fat on a low-fat diet?

Losing weight on a low-carb diet:

Low-carb diets are characterized by low levels of blood glucose and insulin.

When there is a decrease in circulating glucose and insulin concentration:

These are signals for adipose cells to increase lipolysis and release nonesterified fatty acids and glycerol into the circulation.  […] The nonesterified fatty acids are removed by the liver and converted into ketoacids, which then diffuse out of the liver into the circulation. The increase in nonesterified fatty acids results in a concentration-dependent exponential increase in ketoacids […]; glucagon facilitates this process […].

Is that dangerous? For example, what are the effects of a 24-week ketogenic diet?

«Long-term effects of a ketogenic diet in obese patients» (Exp Clin Cardiol. 2004 Fall; 9(3): 200–205)

The present study shows the beneficial effects of a long-term ketogenic diet. It significantly reduced the body weight and body mass index of the patients. Furthermore, it decreased the level of triglycerides, LDL cholesterol and blood glucose, and increased the level of HDL cholesterol. Administering a ketogenic diet for a relatively longer period of time did not produce any significant side effects in the patients. Therefore, the present study confirms that it is safe to use a ketogenic diet for a longer period of time than previously demonstrated.

Another one (56-weeks): Long term effects of ketogenic diet in obese subjects with high cholesterol level (Mol Cell Biochem. 2006 Jun;286(1-2):1-9. Epub 2006 Apr 21):

This study shows the beneficial effects of ketogenic diet following its long term administration in obese subjects with a high level of total cholesterol. Moreover, this study demonstrates that low carbohydrate diet is safe to use for a longer period of time in obese subjects with a high total cholesterol level and those with normocholesterolemia.

Ketones are substances that are made when the body breaks down fat for energy. If your blood glucose is within a safe range and you are losing weight, the presence of ketones may be perfectly normal.

 

Losing weight on a low-fat diet:

The short answer:

High-carb diets increase blood insulin levels and insulin inhibits lipolysis. Without lipolysis you can’t lose body fat. No wonder high-carb diets very seldom work for weight loss.

You can jump now to the conclusions at the end of the post.

The long answer:

Let’s forget about insulin and let’s assume lipolysis is mostly not inhibited. In hepatocytes, nonesterified fatty acids (NEFA) resulting from lipolysis can be used for (see diagram below) a) energy production (Kreb’s cycle), or b) re-packaged into triglycerides and exported as very low density lipoproteins (VLDL) or c) stored within the liver, or d) converted to ketones.

If the «official high-carb low-fat diet» were useful for losing weight, it would promote lipolysis and therefore increase also (see diagram above) one or more of the following:

1. ketone levels in the blood. And, if you were to lose a lot of weight, that effect would be prolonged in time, right? Didn’t they say that was dangerous? It is NOT!
2. triglyceride (TG) levels in the blood, a well-stablished risk factor for CVD. Don’t they know that is dangerous?
3. fat stored in the liver, creating a fatty-liver (but not all the re-esterified TG can be stored in the liver, so this is not an option). Don’t they know that is dangerous?

Esterified fatty acids in the liver would not vanish in the air. Where would they go: ketones or TG in the blood? If low-fat diets worked for weight loss, they would be dangerous! (according only to their own words because ketones are not a danger for healthy people)

But forget those dangerous effects because high-carb diets increase blood insulin levels and insulin inhibits lipolysis. Without lipolysis you can’t lose body fat. No wonder high-carb diets very seldom work for weight loss.

As I said at the beginning of this post, the high-carb «car» doesn’t create pollutants because it doesn’t even have an engine. It doesn’t burn fat, so obviously there are no undesired end-products.

Conclusions:

• Low-carb diets (and ketosis) are a healthy option for weight loss
• High-carb (low-fat) diets are the perfect recipe for making people obese

Further reading:

• Ketosis – advantaged or misunderstood state? (Part I) by Peter Attia
• Ketosis – advantaged or misunderstood state? (Part II) by Peter Attia
• Is ketosis dangerous? by Peter Attia
• ¿Existe diferencia entre cetosis y cetoacidosis? by Ana Muñiz