[Obesity-- current significance of nutritional therapy].

Obesity is defined as pathologic increase of body fat leading to an increased health risk. Obesity therapy should be initiated if the body mass index is higher than 30 kg/m2 or if consecutive diseases occur. In cases in which a weight reduction of at least 20% is warranted by conservative therapy strategies, only very low calorie diet can achieve it. For practical reasons, a three-month formula diet can achieve the goal best, as shown in clinical trials, provided that the diet is administered within a so-called "basic therapy program" over 6-12 month that changes life-style. The basic therapy program covers apart from the dietetic approach behavior therapy, exercise therapy, and medical care. The initial formula diet represents an initial aid, similar to anti-obesity drugs or the gastric banding, although comparative studies on the three procedures are lacking.