The 21st century will become the century of obesity. Attempts to manage overweight and obesity are generally unsuccessful. Many patients reduce their weight, but few can maintain this reduction. A high-carbohydrate diet is recommended by many scientific societies as a classical treatment of obesity. However, its effectiveness and compliance remain unsatisfactory. Taking into consideration the beneficial result of weight reduction on type 2 diabetes and cardiovascular diseases, many scientists are looking for safe and well accepted diets in the treatment of obesity. Their efforts have focused on experimental diets such as high-protein or high-fat ones.