The Dukan Diet is a popular protein-intensive weight loss diet that was designed and popularized by French doctor Pierre Dukan. After helping an obese patient lose weight early on in his career, Dr Dukan developed a sustained interest in nutrition and effective weight loss (1). He published three other books before publishing the global bestseller The Dukan Diet (2000), which has since sold over 11 million copies and been translated into 14 languages (2). The diet has been surrounded by controversy since its inception, for reasons detailed below. Find out for yourself the pro and cons of the Dukan diet with our complete Dukan diet review.
The Four Stages of the Dukan Diet
Part of the Dukan Diet’s appeal lies in allowing adopters to eat as much as they want, provided that stick to protein-rich food and religiously avoid fats and carbohydrates. It promises a loss of up to 10 pounds during the first week, followed by a loss of 2-4 pounds per week until the target weight is reached (4). Many people have found the diet easy to follow, since it provides a clear list of restrictions and does not involve calorie counting.
Dr Dukan has argued that accelerated weight loss is achieved by limiting the body’s caloric intake. Protein-intensive foods contain fewer calories per gram than foods rich in fats and carbohydrates, are more filling, and require more time and metabolic energy to digest while yielding fewer calories. This forces the body to burn stored fat for energy, thus prompting hasty weight loss.
Scientists have observed that the prescription to increase one’s daily protein intake while reducing carbohydrate consumption is common in many popular diets. This generally promotes weight loss because the high intake levels of protein increases the amount of energy expanded during digestion (via a higher thermic effect of feeding) while prompting premature satiety when eating (5). The reduction in carbohydrate and fat intake, on the other hand, reduces total serum cholesterol and promotes glucose tolerance, allowing adherents to achieve clinically relevant weight loss (6).
1. Dukan Diet Attack Phase
During the Attack phase, the Dukan Diet limits adopters to any of the 68 natural animal proteins (e.g. red meat, white meat, organ meat, seafood, eggs) and several plant proteins (e.g. tofu), 1.5 tablespoons of oat bran and 6 to 8 cups of water a day (to help eliminate the ketones produced by protein digestion) (7). The restriction of carbohydrates causes the body to shift from a state of glycolysis to ketosis, where the concentration of ketone bodies in the blood increases as fat is burned for energy (8). While ketosis is a generally benign state, it could lead to ketoacidosis (ketones are acidic, and acidosis occurs a sustained excess of ketone bodies causes blood pH to fall below 7.35) in individuals who are predisposed to the condition (9).
As with the other phases, regular exercise (particularly brisk walking) is encouraged to facilitate fat burning. This phase typically lasts up to 10 days, depending on the amount of weight to be lost.
Oat bran is the sole source of carbohydrates during this phase, and it has also been included because of its other beneficial properties: (1) it contains soluble fiber, which reduces the absorption of low-density lipoprotein (LDL) (i.e. ‘bad’ cholesterol) into the bloodstream; (2) soluble fiber absorbs an average of 25 times its volume in liquid, forming a large gel-like substance (a bolus) in the stomach that creates a feeling of fullness; (3) the formation and ingestion of the bolus slows down the processes of sugar assimilation and the absorption of dietary fat during digestion, helping to maintain low and stable blood sugar levels (10).
Oat bran was chosen over oatmeal since it contains approximately 50% more fiber and soluble fiber than oatmeal. It also contains higher levels of protein, calcium, iron, thiamin, phosphorus, riboflavin, magnesium, and zinc (11).
2. Dukan Diet Crusie Phase
During the second phase, the Dukan Diet allows the consumption of 32 non-starchy vegetables (alongside the 68 allowed proteins. This allows for cucumbers, collard greens, celery, asparagus, mushrooms, and zucchini, while barring carrots, sweet potatoes, potatoes and sweet corn. Naturally, the reintroduction of vegetables ensures that the important vitamins, minerals, and fiber needed for a healthy diet are not permanently omitted.
Adopters alternate between Pure Protein (PP) and Pure Vegetables (PV) days in a 1:1 ratio, depending on the amount of weight to be lost. Those who aim for greater weight loss can adopt a greater alternation, e.g. four days of PP followed by four days of PV (12). During this phase, most individuals aim to lose an average of 2 pounds each week.
3. Dukan Diet Consolidation Phase
This phase is aimed at preventing users from regaining the weight they lost. Its length is proportional to the amount of weight lost: five days for every pound. During this phase, the Dukan Diet prescribes the same proteins and vegetables from the previous two phases – but without the need to alternate between PP and PV days. However, one day of the week should be designated as PP.
In addition, adopters should consume the following: one to two fruit servings, two slices of whole-grain bread and 1.5 ounces of cheese each day; two starchy food servings per week; one serving of lamb and roast pork per week; one to two ‘celebration meals’ each week (which includes 1 appetizer, 1 entrée, 1 dessert and 1 glass of wine) (13).
4. Dukan Diet Stabilisation Phase
The final phase restores full spontaneity in terms of food choice – provided that three ‘non-negotiable’ practices are maintained: (1) 3 tablespoons of oat bran are consumed each day; (2) one PP day per week; (3) regular exercise is incorporated, e.g. by always taking the stairs instead of the lift (14).
Dukan Diet Reviews
The Dukan Diet is particularly restrictive in the early stages. While users have a free range in choosing protein options, they have to be careful to ensure their food is prepared without oil and butter (using herbs and spices to add in flavor is recommended). Meals suited for the Attack phase include steamed chicken, boiled eggs, fat-free yogurt, steak, smoked salmon and tofu kebabs. Salads and steamed vegetables can be reintroduced during the Cruise phase, before more food options become available in the Consolidation and Stabilisation phases.
Vegetarians and vegans will face severe dietary restrictions when attempting this diet, given its emphasis on lean sources of protein. Seitan, tempeh, and tofu are allowed as vegetable protein options, but beans, nuts, and lentils have been omitted.
Precautions
While the Dukan Diet claims that medical studies have validated its safety and effectiveness, it has received its fair share of criticism (15). When the US News and World Report conducted its Dukan diet review, it listed lethargy, bad breath and constipation as side effects, and pointed out that the high protein intake could lead to long-term health problems (16).
An independent Polish scientific review of the Dukan diet which studied 51 women, arrived at the same conclusion, observing excessive protein intakes and levels of potassium, iron and vitamins A, D and B2 alongside low levels of vitamin C and folates. While the women who participated in the study reported an average weight loss of 15 kg after 8-10 weeks of dieting, many also registered nutritional abnormalities, flagging concerns of them acquiring kidney and liver disease, osteoporosis and cardiovascular disease in the long run (17).
Australia’s government-funded HealthDirect reviewed the Dukan diet and warned that the Dukan Diet’s strict restrictions of carbohydrates can be harmful and unsustainable in the long term, since carbohydrate-rich foods provide the energy, fibre, vitamins and minerals needed for a healthy diet (18). HealthDirect does also note, however, that some of its principles – limiting the consumption of excessive fats and refined carbohydrates, promoting regular exercise, water consumption and regular intake of vegetables and lean protein – are congruent with Australian dietary recommendations.
Meanwhile, the British Dietetic Association (BDA) has listed the Dukan Diet as the number 1 diet to avoid in 2010, 2011 and 2012 (19).
Conclusion
The logic of the Dukan Diet is sound: protein does lead to longer durations of satiety while limiting calorific intake. While scientists have yet to pinpoint the ideal ratio of dietary carbohydrate to protein for optimum health and weight management, research indicates that increasing the ratio of protein to carbohydrate in the diet of adult women resulted in improvements with regard to body composition, blood lipids, glucose homeostasis and satiety levels alongside weight loss (20).
Many nutritionists also approve of Dr Dukan’s recommendation of lean protein sources over protein sources that come with high amounts of saturated fat. It is worth noting, however, that recent studies have questioned the ‘demonisation’ of saturated fats and its traditional association with coronary heart disease (CHD) (21). Recent evidence indicates that the benefits of a low-fat diet (especially diets that strictly avoid saturated fatty acids in particular, and those that recommend that saturated fats be replaced by carbohydrates) are limited (22). A 2013 Danish study discovered that men with a high intake of saturated fat registered lower sperm concentrations and total sperm counts, however, suggesting that there is a safety threshold for saturated fat consumption – even if the longstanding association with cardiovascular disease has been recently debunked (23).
Moreover, the research on the long term effects of a high-protein diet on health and weight are presently inconclusive. The available data indicates that consuming protein at levels greater than two to three times the U.S. recommended daily allowance contributes to urinary calcium loss, which predisposes adopters to bone loss in the long term (24).
Researchers have also noted the risks for developing kidney stones during or after a high protein diet, and advise individuals with a known history of stone disease to avoid such diets altogether (25).
Lean protein is also relatively costly, prompting additional food expenses over time. Complying with the diet’s severe restrictions in the first two stages will probably prove to be difficult and boring. Furthermore, the complete lack of restrictions during the Stabilisation phase might lead to weight regain if the user reverts to his or her unhealthy eating habits.
The Dukan Diet may be helpful for individuals aiming to lose a relatively small amount of weight in a short period of time. Individuals with medical conditions such as diabetes, renal diseases, and heart diseases, as well as those who are aiming to lose a relatively large amount of weight, should consult their doctor before embarking on the Dukan Diet (26).
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