Bariatric-surgical intervention should be carried out in specialised establishments. The decision about which surgical procedure is suitable in an individual case – restrictive or a combination of restriction and malabsorption – depends on the BMI, the individual risk, the co-morbidities and the patient’s wishes. Decision criteria are not evaluated.
The effectiveness of bariatric procedures has been proven in numerous studies. Depending on the procedure,weight reduction varies between 21 and 38 kg after one year and 15 to 28 kg after 10 years. Calculating the loss of excess body weight, this amounts to 41-54 % for a gastric band, 62-75% for a stomach by-pass and 66-74% for a biliopancreatic diversion or duodenal switch.

Patients who have experienced massive weight loss are not comparable with patients of the same weight who have not undergone an extreme fluctuation in weight. On the one hand there is the problem of the excess skin which has reduced turgor and increased elasticity. On the other hand there is the risk of anaemia and vitamin and mineral deficiency, in particular in patients who have undergone a stomach bypass. Strict follow up of patients following bariatric surgery is vital, ideally every 2- 3 weeks during the first 3 months, then 6 and 12 monthly post-operative and subsequently yearly.
Laboratory examinations should be carried out in good time before the scheduled operation in order to be able to react to any symptoms of deficiency. The patient must be shown a balanced nutritional intake several times. An adequate level of protein in the diet promotes healing, correct iron levels are vital in the treatment and prevention of anaemia and a good nutritive status supports complication-free healing. 

The psychological consequences of obesity are as significant, if not more significant, than the medical consequences mentioned above. In many cases the psychopathology observed is a result of prejudice and discrimination which the patients have often been subjected to since their youth. Laughing at and taunting “fatties” is deeply rooted in society.
Studies show that, following massive weight reduction by bariatric surgery, self-confidence and positive emotions increase significantly and the disparagement and denigration of the body diminish. For the first time these patients feel they are part of society. After massive weight reduction patients report improved fitness, mobility, increased performance, mental strength, self-confidence, social interaction and far higher satisfaction with life as a whole.