Science behind the Dukan Diet: Ketosis, Carbohydrate Restriction and Metabolic Effects

August 24, 2011

in Introduction

Why do I investigate facts in favor of the Dukan Diet? The method proved to be effective. I followed it to lose 40+ lbs and I know people who also were able to successfully lose weight thanks to the Dukan Diet. Therefore, in spite of all the critics, there must be some valid science behind the method. I am here to find it.

Why do I investigate the diet’s objectors arguments? I don’t blindly follow everything I’m said. I always take both sides of the story into consideration. There were some voices raised against the dukan’s plan and I am willing to investigate whether they are based on a solid ground or not.

I took the liberty to find some scientific research on the low-carb, low/medium-fat and high-protein nutrition plans to back up the hypothesis of the effectiveness of the Dukan’s method. Here’s what I found out.

The effects of carbohydrate restriction

This fragment is based on a study ‘Carbohydrate Restriction has a More Favorable Impact on the Metabolic Syndrome than a Low Fat Diet’. All quotes (if not indicated otherwise) come from: (US National Library of Medicine). The said study treats the topic in a great detail. I took the liberty of choosing only a few excerpts to illustrate my point of view and back up my thesis with some real scientific knowledge.

Calorie intake

About spontaneous reduction in calorie intake caused by high-protein menu:

CRD (Carbohydrate Restricted Diet) provides a spontaneous reduction in calorie intake. The higher consumption of the high-protein foods implies a lower calorie intake even if the amount of the food eaten was not intentionally limited. I would account that for the high-protein foods overall lower calorific value and the fact that digesting protein takes significantly more time and energy than the digestion of carbohydrates.

An excerpt from the above-mentioned study:

Although not specifically counseled to reduce calories, there was a reduction in total caloric intake (…) Spontaneous reduction in calories on CRDs was first shown by LaRosa in 1980, and there are several studies showing that, in practice, people tend to remove carbohydrate without replacement of either fat or protein. Interventions where weight loss is at least an implied goal may generally have this effect.

I can speculate that, since the Dukan diet is both low-carb and low-fat, the effect of restricting carbohydrates and fats in the same time can amplify the weight loss effect. On the other hand, the dukan method doesn’t cut off all the carbs or fats and thus, despite what some people imply, I consider the Dukan’s method presents quite a balanced menu. It’s worth mentioning here that, amidst the protein rich foods Dukan recommends, there are three groups that stand above others: fish, seafood and diary. Fish and seafood provide healthy fats and fat-soluble vitamins while diary is a very good source of calcium.

Glycemic and Insulin Improvement

All subjects in this study were overweight and had elevated values for leptin at baseline, an indication of leptin resistance.

Leptin is a protein hormone that plays a key role in regulating appetite and metabolism. Leptin is an appetite suppressant but obese people are said to be resistant to its effects. The result is that in leptin insensitive people the body doesn’t an adequate satiety feeling. The said study shows that the dietary restriction of carbohydrates contributes to rebuilding the leptin sensitivity in obese patients.

These values were markedly reduced in subjects following the CRD (-42%) (…) The significantly greater decrease in leptin in subjects following the CRD persisted after normalization of values to body mass and fat mass.

Untoward Metabolic effects of the low-carb nutrition plans

A paper on ‘Metabolic Effects of High-Protein, Low-Carbohydrate Diets’ by Margo A. Denke, MD covers some of the low-carb, high-protein nutrition plans’ side-effects (I chose only a few that concerns the Dukan’s method):


Children following these ketogenic diets have higher rates of dehydration, constipation, and kidney stones. Other reported adverse effects include hyperlipidemia, impaired neutrophil function, optic neuropathy, osteoporosis, and protein deficiency. Source: ‘Metabolic Effects…’ by Margo A. Denke

While I don’t argue with the above-quoted it is a matter of interpretation whether the dukan diet is that much ketogenic. What’s even more important is to make a distinction between ketogenesis, ketosis and ketoacidosis.

The latter is a pathological metabolic state that, even when following the ketogenic diet, can be easily prevented by sufficient hydration and not prolonging the strict dieting periods (as in Dukan’s Attack Phase which is advised to be carried out for no longer than 7 days).

As far as the Dukan’s plan is concerned, the greatest ketogenic effect is to be expected at the very beginning of the diet (the Attack Phase) which only lasts for only a few days. Later on, the menu extends and one is advised to supplement his or her meals with a number of vegetables that, to my knowledge, further counteract the occurrence of the unwanted ketoacidosis.

On the other hand, ketosis is:

(…) a functional aspect of fat-based energy metabolism, induced by prolonged fasting or a low-carbohydrate diet. Source:

This means there’s no much risk of any untoward effects in relatively healthy people and the ketosis itself is the mechanism that provides the weight loss every dieter count for:

When the body is in ketosis the individual tends to feel less hungry (…) The body switches from being a carbohydrate-burning organism into a fat-burning one. The fat stores become a primary energy source, and the person loses weight. Source:

Exclusion of fruits, vegetables, and grains

Because they exclude fruits, vegetables, and grains, low-carbohydrate, high-protein diets are deficient in micronutrients. Children consuming low-carbohydrate ketogenic diets have reduced intakes of calcium, magnesium, and iron. Source: ‘Metabolic Effects…’ by Margo A. Denke

Again, when we talk about the dukan Diet, it is worth mentioning that after the attack Phase the menu is being gradually extended. After the Phase II the food list contain starchy food, grains and fruit. I don’t see much of a risk of any of the above-mention minerals deficiency. Let’s take a quick look at the 100 safe food list:

Foods rich in calcium: diary (e.g. yogurt, quark), fish (sardines, sprats), tofu.

Foods rich in magnesium: fish (halibut, cod), oat bran, spinach.

Foods rich in iron: liver, mussels, fish, beef, oat bran

In my opinion, there’s no reason to worry about any micronutrients deficiency. On the other hand, you can always supplement your diet with vitamin tablets if you believe that’s necessary. I don’t.

There’s one more study I came across that shows that moderate ketosis (increased availability of ketone bodies) may bring some more health benefits than just weight loss.

In a low-carbohydrate diet, the increased availability of fatty acids and ketone bodies may inhibit aggressive glycolytic cancers. Source:

High-protein intake

Doctor Denke suggests that, in short, high-protein intake puts additional burden of kidneys. This is true and, basically, this is how the metabolism of protein works. The Dukan Diet is not suitable for people with kidney problems but there’s no evidence that it may harm the urinary system in healthy people. Moreover, as stated before, the periods of high protein intake during the diet alternate with the periods of a balanced protein-vegetable menu ensuring that the risk of the body’s over taxation is minimized.

This is my review on some scientific study on the various effects of the low-carb diet. There’s another article on some common Dukan Diet Cons here.

{ 4 comments… read them below or add one }

teresa powell January 25, 2012 at 5:37 PM

having followed the dukan diet to the letter ,I lost 25lbs succesfully . Being very happy withmy weight I continues my oatbran daily , protein thursdays ,excersice regular but this past 2mths my weight is creeping back I gained 3kgs , now I have introduced wine back into my diet ,in moderation, could this be the reason , as I feel that I did previously gain with alcohol, hope you can answer my dilema as I do not want togain the weight again , but feel that alcohol is apart of my social life and it would be good to have the privelage without the weight issue as previous .


Elena February 13, 2012 at 7:33 PM

Hi there, I am not a doctor, I consider myself as a safer on the Dukan diet.
Like you I have started on November and lost 13 lb, so I have reached the ideal weight, I started to try bread and some cheese… during 2 weeks – 2.5 kg back. I feel so bad and started to read more information on the any possible sources. If you have some thoughts, please share it with me. I would appreciated it. -elena.kameneva at


admin February 13, 2012 at 7:55 PM

Have you stayed on the diet for all the 4 stages?


Elena February 13, 2012 at 10:31 PM

Not yet… I have started 3rd face 2 weeks ago. I am thinking to go back for some Protein days, let say 2-3. And after that again PP and VP, but where is exit?


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