Some nutrition and health care specialists say that the diet's shortcomings -- side effects such as constipation, lousy breath and low energy -- are in fact clear warning signs that this is a diet with serious limitations.
Critics say the program isn't balanced, since it eliminates so many healthy food groups. They question whether it's another short-term fix to a long-term issue and can lead to yo-yo dieting. And they warn that it can put undue stress on your kidneys and digestive system.
Any "quick fix" diet poses some risk, say diet experts. Keri Gans, a spokeswoman for the American Dietetic Association told WebMD's Kathleen Zelman that "It is unhealthy to lose weight so quickly because you not only lose fat and fluids but precious muscle mass, which is really hard to replace, especially as you get older" [source: Zelman].
Dukan encourages dieters to take a daily multivitamin with minerals, to help remedy some of the plan's shortcomings. However, some experts warn against an over-reliance on vitamins, instead of getting those essential ingredients from whole foods. Dr. Oz suggests that Dukan participants taking one half of their multivitamin in the morning, and the second in the afternoon, to ensure that the body absorbs more of the nutrients [source: Holland]. Perhaps the best test of any diet is whether it's successful over the long haul, and the jury is still out on Dukan.
Will The Dukan Diet work for you?