Although I’m firmly convinced that Atkins is the best way for most people to slim down and stay there, I’ve never believed in bashing other diets. If you find something else that works for you—both for weight loss and weight maintenance— congratulations. But I now find that I must make an exception when it comes to the Dukan Diet.
If you haven’t heard of Pierre Dukan, a French neurologist, you will shortly, as a book on his diet will soon be published in the United States. In a recent article in The New York Times, Dr. Dukan said, “I am built on the shoulders of Weight Watchers and Atkins diets.” But it’s not his effort to ride the 40-year wave of Atkins popularity that concerns me. Nor is it that the Dukan Diet is a copycat program. In fact, it actually bears scant resemblance to the New Atkins Diet, as you’ll learn below. Think about it: how could a hybrid of Atkins and Weight Watchers even come close to our signature low-carb program?
Research? Nada. Safety? Uncertain
No. My real opposition to the Dukan Diet is that there’s absolutely no scientific research to substantiate any of its claims—and therefore no evidence that it works or that it’s safe. Contrast that with the more than 60 studies published in peer-reviewed journals that have consistently validated the safety and efficacy of the Atkins Diet. Moreover, over-consuming protein, which the Dukan Diet calls for, could be risky.
Minor Similarities, Major Differences
Yes. There are some superficial similarities between the Atkins and Dukan diets. Both consist of four phases, with the first one designed to kick-start weight loss, the second to reach or get close to goal weight, the third to stabilize weight loss and the fourth an ongoing way of life. Neither diet asks you to track calorie intake. Both control intake of carbohydrates, rely primarily on whole food sources and recommend incorporating activity into the program after the first two weeks. Beyond these basics, the two diets differ significantly in the ratios of the three macronutrients of protein, fat and carbohydrate allowed. There are also very different philosophies in the approach to changing dietary habits to achieve the real goal: permanent weight loss.
The Proportion of Protein
Protein is essential to building and repairing cells, among other life-preserving functions. Protein helps you feel full so you don’t overeat and helps stabilize blood sugar levels. Protein is also about 25 percent harder to digest and metabolize than carbohydrate or fat, meaning you burn extra calories in the process. All these reasons explain why protein is an important component of Atkins, but it is by no means a high-protein diet. We recommend people consume adequate protein, meaning about 4–6 ounces (tall men could have up to 8 ounces) at each meal. This averages an intake of 13–22 ounces a day, which falls within most nutritional guidelines. Moreover, we caution that eating more than the recommended amount of protein can stall weight loss.
In contrast, the Dukan Diet allows its followers to consume unlimited amounts of protein. By simultaneously restricting natural fats and practically eliminating carbohydrates, including all vegetables (!) in the initial phase, you’re left with only one option: protein. Of course, most protein sources also contain some fat. Stuck in the old paradigm that dietary fats are always unhealthy, Dr. Dukan specifies low-fat meats, poultry and cheese. His effort to avoid fat results in a disturbing excess of protein. My analysis of the initial phase suggested menu reveals that 62 percent of calories consumed comes from protein, compared to 30 percent for Atkins. That’s more than double the amount!
How About Carbs?
Also of concern is the absence of vegetables on the initial phase of the Dukan Diet. As you well know, even in Phase 1 of Atkins, when you reduce your intake of simple carbs, you’re still getting complex carbs in the 20 daily grams of Net Carbs comprised primarily of leafy greens and other low glycemic vegetables. Depending on which foundation vegetables you select—there are almost 90—you could be getting anywhere from five to 10 USDA servings a day. These veggies are a valuable source of vitamins, minerals, antioxidants and numerous other phytonutrients. They also supply fiber, which helps keep you regular and slows the conversion of carbs to glucose, moderating the blood sugar roller coaster. Fiber also scrubs your arteries of plaque, helping reduce the risk of heart disease.
So how many vegetables would you get to eat in the first phase of the Dukan Diet? Zero! That right, not a single vegetable, unless you want to count a few herbs in some recipes. Even in the second phase you alternate days of eating what Dr. Dukan calls “pure protein” (although it obviously includes some fat) with days in which you combine protein sources and vegetables, choosing from a list of 25 veggies. Just to be clear, this means that every other day you eat no cooked veggies and not even any salads, nada! As a result, these valuable sources of fiber (to say nothing of micronutrients) simply aren’t on the menu. And this pattern of eating continues possibly for months on end if you have a lot of weight to lose. No wonder two tablespoons oat bran is an absolute daily requirement!
After two weeks in Induction on Atkins, you begin to add new carb foods, including first nuts and seeds and then berries and a few other low glycemic fruits like cantaloupe. These foods add variety, helping relieve boredom. Not long after that, yogurt, fresh cheeses and legumes round out the menu. On Dukan, no fruit—and that includes berries—is allowed until the third phase, in which you stabilize your weight. Even nuts, which are full of essential fatty acids and have been shown to cut the risk for heart disease, can be eaten only occasionally and not until one has achieved goal weight.
Fat Is Your Friend on Atkins but Not on Dukan
When you follow the Atkins Diet, you switch your body from burning primarily carbohydrate, in the form of glucose (sugar) to burning primarily fat, including body fat. As long as you control carbohydrate intake, there’s no risk in consuming natural fats—you should, however, avoid trans fats—on Atkins. Dr. Dukan doesn’t agree—that’s where his debt to Weight Watchers comes in. His recommendation: eat only lean meats and poultry and low-fat dairy products (which, of course, are higher in carbs—go figure).
As mentioned above, in the first phase of the Dukan Diet, followers eat only low-fat protein and virtually no carbs. Eliminating carbs, reducing fat and relying solely on protein for energy is extremely inefficient. This approach also starves the body of essential nutrients such as vitamins A, D, E and K, which are soluble in fat but not in water. Fat plays a major role in moderating blood sugar levels, which helps maintain energy level and keep hunger and cravings under control. The calories from natural fats may be the very thing you need to get your metabolism tuned to the right mix of fuels. Fat is the essential nutrient that makes low carb safe and effective. Protein can’t do the job alone. The tag team of protein and fat keeps you from being deprived and avoids the negative impact of excessive protein.
Fat Makes Low Carb Work
I asked Dr. Jeff Volek, associate professor at the University of Connecticut and coauthor of The New Atkins for a New You, for his views on the Dukan Diet. “Long-term success on a carbohydrate-restricted diet requires more than a casual approach and the Dukan Diet falls short,” he said. “Dr. Dukan’s approach ignores the well-documented fact that people vary in their ability to metabolize carbohydrates and that when carbohydrate intake is low, increasing fat intake has an important role in providing fuel, flavor and functional satiety.” In other words, you need fat to stay energized, savor the taste of food and feel full. And when your energy level is high and you’re tummy isn’t rumbling with hunger, you don’t overeat. In fact, any diet that skimps on natural fats is inherently unsatisfying, making it extremely difficult to sustain long term and almost certainly doomed to failure.
Maintaining Weight Loss
Dr. Dukan claims that to maintain weight loss you “shock your body” into fat burning by reverting once day a week to the program’s stringent guidelines for phase one. The rest of the week, you can “eat whatever you want,” according to the Dukan website. This approach has absolutely no basis in physiology. It takes three or four days for the body to shift from a glucose (carb-burning) metabolism to a primarily fat-burning one. By returning to a low-fat, higher-carb diet for six days a week, a person will likely never sustain fat burning. This advice also flies in the face of all we know about yo-yo dieting. As soon as people return to their old way of eating (whether six or seven days a week), they are almost certainly going to regain the pounds they lost.
On the other hand, Atkins followers are encouraged to find their own personal carb tolerance level, which consistently keeps their body in the fat-burning metabolic state, allowing them to maintain their new weight—for good.
The Last Word
I also asked Dr. Eric Westman, who is director of the Duke Lifestyle Medicine Clinic and another coauthor of The New Atkins for a New You, to chime in. “As a scientist who keeps up with the literature, I am not aware of any studies that have been published about the Dukan Diet," whereas the Atkins lifestyle was developed from a clinical practice that treated obesity, diabetes and other metabolic problems for over 30 years and then repeatedly tested the diet in clinical trials with excellent results.” Enough said.
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