Also key to the rapid weight loss is converting the body's metabolism into what nutritionists call a state of ketosis. This normally occurs only during starvation conditions, but also can be achieved by virtually eliminating carbohydrates. Other problems arise as the body copes with a lot of protein. Stress on the kidneys increases, with the possibility of kidney stones. With ketosis, a chemical called uric acid can build up in the blood, leading to gout, a painful condition of the toes and joints.
Osteoporosis is also of concern.
Not only is calcium low in the diet, but it is excreted from the body along with the excess protein. And the large amount of saturated fat in the diet raises the risk of heart disease. Stern emphasizes that studies have shown repeatedly that the healthiest diet is high in whole grains, cereals, fruits and vegetables, and very low in fat, especially the saturated fat in meat and cheese. Such a diet, high in vitamins, minerals and fiber, is associated with a reduced incidence of heart disease, diabetes, stroke and many cancers. According to Stern, when such dieters return to their normal eating patterns, their weight creeps back up to previous levels or even higher.