Weight Loss & Diet Plans

'The Dukan Diet' Review

The Dukan Diet: How It Works

In theory, this is how the plan works: Phase 1 promotes rapid weight loss with a protein-only diet.  Stay on this phase anywhere from 1-10 days, and expect to lose at a rate of 7 pounds in 5 days.

During Phase 2, which could last for months, depending on how much weight you need to lose, your body recuperates and adjusts to your weight loss.  Dukan recommends sticking with this phase until you reach your goal weight, with the expectation of dropping 2 pounds per week.

Phase 3 is the critically important period between weight loss and maintenance, when the plan lightens up a bit but no weight loss is expected.  This is a time when your body is vulnerable to putting pounds back on, according to the book. But if you stay in this phase five days for every pound you've lost, the book says, you'll avoid regain. 

Phase 4, the maintenance part of the plan, is meant to be lifelong. You'll keep the weight off for good, the book says, if you follow this phase's requirements for a weekly all-protein day, plus oat bran and exercise.

The Dukan Diet: What the Experts Say

You'll certainly lose weight on The Dukan Diet because it cuts calories drastically. The lack of carbs also helps keep hunger at bay. But the bottom line, experts say, is that this eating plan does not include all the nutrients you need for good health.

"A once-daily multivitamin will not compensate for the nutritional goodness from fruits, whole grains and healthy fats that are inadequate in The Dukan Diet," says Keri Gans, MS, RD, a spokesperson for the American Dietetic Association.

She points out the health hazards of restrictive dieting.  “When dieters start losing weight rapidly, I worry they will continue the restrictive phases longer than advised -- which puts them at risk for nutrient deficiencies and kidney problems," says Gans.

Losing more than 1-2 pounds per week can promote gallstones and muscle loss, she says:  "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."

Constipation, bad breath, dry mouth, and fatigue should be a red flag that this is not a healthy diet, she says.

 "Your body’s preferred fuel to energize and keep you going is smart carbs, and when you eat a healthy diet you should feel great -- not have negative side effects," Gans says.

The Dukan Diet: Food for Thought

There is no question this very restrictive diet will lead to weight loss, if you can actually follow it.  But the elimination of healthy food groups, and the unpleasant side effects, makes The Dukan Diet an unlikely choice for the long haul. 

Protein is an essential part of a healthy diet, but it cannot stand alone.  A truly healthy diet includes all the food groups -- vegetables, fruits, whole grains, and low-fat dairy and healthy fats along with lean protein. Your body needs the nutrients these foods provide.

Skip this fad diet. Instead, choose a calorie-controlled eating plan that you can stick with for the long term.

Kathleen Zelman, MPH, RD, is director of nutrition for WebMD. Her opinions and conclusions are her own.