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The Dukan Diet is a high-protein, low-carbohydrate diet promoting rapid weight loss and promising lasting results. While this may sound appealing, the diet does have multiple drawbacks, especially for those with diabetes.

Learn more about the Dukan Diet and if it's optimal for those with diabetes.

What Is the Dukan Diet?

The Dukan Diet is a low-carbohydrate, high-protein weight-loss diet created by the French doctor Pierre Dukan. The diet consists of four distinct phases—Attack, Cruise, Consolidation and Stabilization, and is designed to promote rapid weight loss. Each phase has a specific set of rules, starting with the most rigid guidelines and a limited list of allowed foods in the first phase and followed by progressively more liberal guidelines as you move through each subsequent phase of the diet.

Phase 1: Attack

The Attack phase, also called the "pure protein" phase, is the shortest phase of the diet, lasting between two and seven days. In this phase, participants eat unlimited protein from a list of 68 allowed protein-containing foods as well as 1.5 tablespoons of oat bran mixed with water daily. According to the Dukan Diet plan, the expected weight loss in this phase is between 2 and 8 pounds.

Phase 2: Cruise

The second phase, called the Cruise phase, allows for 100 foods including those on the original "pure protein" list. The list is a combination of both proteins and vegetables and doesn't allow for fruit, starchy vegetables, bread or other grains. In addition to the 100 allowed foods, diet followers also up their oat bran intake to 2 tablespoons per day for the duration of the phase. The time spent in the Cruise phase varies by person depending on the amount of weight they would like to lose. According to the Dukan Diet, it's expected that someone will lose 2 pounds per week in this phase.

Phase 3: Consolidation

The Consolidation phase includes the 100 foods allowed in the Cruise phase, but also adds fruits, whole grains, starches and cheeses. This phase requires one "pure protein" day each week plus the continuation of 2 tablespoons of oat bran per day. Followers of the diet can also expect to have two celebration meals per week. It's expected that you remain in the Consolidation phase for five days for each pound lost in the Cruise phase. This means that if you lost 10 pounds in the Cruise phase then you would remain in the Consolidation phase for approximately 50 days.

Phase 4: Stabilization

The Stabilization phase is the fourth and final phase and is intended to last for life. It allows for all foods from all food groups, and like the Consolidation phase, the Stabilization phase requires one "pure protein" day each week. This phase also increases the total oat bran to 3 tablespoons per day.

Note: All phases of the diet encourage daily physical activity.

The Dukan Diet and Diabetes

Living with diabetes requires monitoring blood glucose to ensure it stays within an optimal range. Multiple strategies are used to manage blood glucose, including implementing a physical activity routine, taking medications or insulin as prescribed, and making diet modifications.

"There are many different dietary patterns that can work to manage diabetes and help with weight loss," says Vandana Sheth, RDN, CDCES, FAND, a registered dietitian nutritionist and certified diabetes care and education specialist. "However, one that is very low in carbohydrates, especially as prescribed during the first phase of the Dukan Diet, is not safe."

The Dukan Diet's distinct phases impact total calorie and macronutrient intake in different ways. Because of this, the potential benefits and drawbacks of the diet for someone with diabetes vary depending on the phase.

However, there are some general themes that arise when looking at the recommendations of this diet.

Potential Drawbacks

May Not Be Sustainable for Long-Term Weight Loss

In general, the Dukan Diet is a restrictive, low-calorie diet that's intended to promote weight loss. This may be appealing for those with diabetes who also desire weight loss, as it promises a quick drop in body weight in the first two phases of the diet. But this approach may not be the healthiest choice, especially for those with diabetes.

"It is simple math to understand that people will lose weight if following very low calories as prescribed in the Dukan Diet, but that does not mean this is a healthy and sustainable eating plan," says Toby Smithson, RD, a registered dietitian, certified diabetes care and education specialist, founder of DiabetesEveryDay.com and author of Diabetes Meal Planning and Nutrition for Dummies. "Very low-calorie and low-carb diets are not for everyone, especially when the diet is restrictive," she says.

The Dukan Diet is considered an extremely low-calorie diet, especially in the first two phases. Most often, restrictive diets are not recommended for long-term weight loss, per a 2021 article published in the Journal of Obesity & Metabolic Syndrome. However, in cases where rapid weight loss is recommended for medical purposes, an extremely low-calorie diet along with behavior change programs may be indicated. These types of restrictive, very low-calorie diets are typically prescribed under the care of a medical professional and aren't intended to be followed without supervision.

Studies have shown that high-protein diets, like the Dukan Diet, can be effective for weight loss. However, there isn't a commonly accepted definition of the total protein required for a diet to be considered a high-protein diet.

According to a 2020 article published in the Journal of Obesity & Metabolic Syndrome, some studies define a high-protein diet as one providing up to 45% of total calories from protein, whereas others consider a high-protein diet to be 25% of total calories from protein. On the Dukan Diet, especially in the first two phases, the percentage of total calories from protein can be well beyond 50%.

While the Dukan Diet may promote rapid weight loss in the initial stages, there is limited evidence to suggest that the weight loss is sustainable in the long term.

May Cause Inadequate Nutrient Intake

Because the Dukan Diet eliminates multiple food groups in the first few phases, it increases the risk of inadequate nutrient intake.

A small study of 51 women following the Dukan Diet in Poland found that participants had inadequate intakes of essential nutrients like calcium, vitamin C and potassium, along with excessive intakes of sodium, protein and phosphorus. These imbalances in nutrient intake over the long term have the potential to result in negative health outcomes.

Eliminating multiple food groups, especially plants, also results in a reduction in total fiber intake. Fiber is a type of indigestible carbohydrate found naturally in plants including fruits, vegetables, nuts, seeds, beans and grains. "Consuming foods high in fiber is an important tool for blood sugar management, but the Dukan Diet limits intake of high-fiber foods," says Smithson.

Not only does fiber play a role in managing blood sugar, but eating enough fiber daily is also associated with benefits to cardiovascular health and digestive health. Plus, fiber plays a role in satiety, which may help with weight management.

Goes against Expert Guidelines

Eating a plant-based diet has been shown to have positive benefits for people with diabetes.

The Diabetes Expert Consensus Statement was released in May 2022 and is intended to provide guidelines for those managing type 2 diabetes. Experts identified multiple consensus statements related to diabetes management, including diet interventions. A key aspect of the statement was related to the importance of eating plants when managing diabetes.

"The recommendations highlight [that a] plant-based eating plan should be the foundation of a healthy eating plan for people managing their diabetes," says Smithson. "The Dukan Diet guidelines are not designed to be a plant-based eating plan."

While the Stabilization phase encourages eating foods from all food groups, it also prioritizes a "pure protein" day each week. The Dukan Diet does not meet the definition of a diet that's made up primarily of plants as defined in the consensus statement.

Potential Advantages

Despite the multiple drawbacks of the Dukan Diet, there are a few potential benefits to following the diet if you have diabetes.

Encourages Physical Activity

One of the benefits of the Dukan Diet is that it encourages physical activity in each phase of the diet. Physical activity is associated with improvements in insulin sensitivity and blood glucose management. Physical activity is also associated with improvements in cardiovascular health and has been shown to play a role in weight management.

Might Promote Healthier Habits

If you choose to follow the Dukan Diet, it may be better to skip the first two phases and go right to the Consolidation and Stabilization phases. Because both phases encourage a wide variety of foods, they're a better choice for those with diabetes.

"Of the four phases, the Consolidation and Stabilization phases hold the most promise for blood sugar management simply because there are more food choices like fruit and other carbohydrate-containing foods," says Smithson.

However, the Consolidation and Stabilization phases still encourage one "pure protein" day, which should be skipped if you have diabetes because of the very low carbohydrate intake. "There is a risk for hypoglycemia, especially if you are taking insulin and other diabetes-related medications," says Sheth.

Diet Red Flags

With so many popular diets available today, it's impossible to identify all the red flags in each diet plan. However, there are common themes to be on the lookout for when considering whether you should follow a new diet.

According to Becky French, M.S., RDN, CLT, an assistant dietitian coach at Nutrient Rich Life, red flags include diets that withhold multiple food groups, as well as those that have the same protocol for everyone. "Each person has their own unique carbohydrate thresholds, and cookie-cutter diets like the Dukan Diet should be a huge red flag," she says.

Sheth is also wary of diets that eliminate food groups and shares six additional red flags to be on the lookout for before starting a new diet. "If the diet is very restrictive and unsustainable, if it encourages overconsumption of a specific food while avoiding others, if it is promoted by a celebrity/influencer but no science-based evidence, if it is very low in calories, if it causes you to feel shame or guilt if you decide to eat normally, or if it enhances anxiety and stress around food and food decisions including eating with your family/friends and other social situations" are all diet red flags according to Sheth.

The Bottom Line

Many popular diets promise fast and lasting weight loss, and the Dukan Diet is no exception. Despite the promising claims, this diet is unlikely to be a healthy choice for those with diabetes.

The diet's restrictive approach results in a very low-calorie diet that's lacking in many nutrients in its first phases. This approach may not be one that you can stick to for long-term weight management.

"It's important to follow an eating plan that is sustainable. If you go on and off an eating plan, your weight and your blood sugar levels will follow that yo-yo pattern," says Smithson.

The best diet for managing diabetes is one that promotes health with optimal nutrient intake while also keeping blood sugar levels within normal ranges. "Healthy eating patterns along with consistent physical activity are key elements of blood sugar management," says Smithson. Be sure the diet you choose is one you can stick to for the long run.