At present, surgery is necessary to counter extreme obesity. The outcomes in bariatric surgery have improved steadily and today most co-morbidities in the massively overweight can be improved or even resolved by surgery. The procedures work in one of two ways; by restricting the patient's ability to eat or by interfering with the ingested nutrient absorption. The operative treatment is in no way cosmetic. Drawbacks to the surgical therapy exist; major life-long rearrangement of the gastrointestinal tract, an operative mortality (<0.5%) and morbidity (about 10%). Surgically induced weight loss is currently the most effective treatment for the severely obese patient.