Since the diet calls for limiting carbohydrates, the dieter may not consume enough fiber, which is mainly found in grains. Lack of fiber may eventually lead to nutritional deficiencies and cause issues with digestion. Dukan Diet side effects that may result from an insufficient fiber intake often include nausea, constipation, and diarrhea. Fiber is also found in vegetables and fruits; therefore, this lack of fiber is more likely to occur in the initial phase of the Dukan Diet when vegetables are not permitted
Another one of the most common Dukan Diet side effects is ketosis. Ketosis is a condition that occurs when the body begins to break down fat for energy, rather than glucose, and result in substances known as ketones that accumulate in the bloodstream. Normal amounts of ketones can safely be released from the body through urination, but an excess amount may end up building up in the blood. Symptoms of ketone build-up include bad breath, headache, nausea, and difficulty concentrating.
Although most of the common Dukan Diet side effects are not life-threatening and will not generally cause long-term complications, serious health issues may occur if the most restrictive part of the diet is followed for an extended period of time. Losing weight too quickly may cause a dieter to lose muscle mass in addition to fat, and lead to problems with gallstones and the kidneys. This may occur with any type of weight loss plan, not just the Dukan Diet, if a person does not retain enough nutritional components from food.
The promoters of the Dukan Diet typically advise taking certain precautions to reduce the likelihood of side effects occurring. It is recommended to take a multivitamin while on the diet to help decrease the risk of nutritional deficiencies. After the desired weight loss is reached, previously restricted foods are reintroduced into the everyday diet and the protein-only portion of the plan is recommended only once per week.