An interdisciplinary team evaluates morbidly obese patients for bariatric surgery. After informed consent eligible patients will be randomized into SG or PGB, a number of 45 per group. Preoperative examination consists of: quantification of comorbidity, eating behavior, indirect calorimetry, body composition by dual energy x-ray absorptiometry (DEXA), routine blood chemistry, gastrointestinal hormones before and after test meal, gastroscopy, manometry of the esophagus, upper GI series, abdominal ultrasound, quality of life. Perioperative investigations: operative time, fat tissue samples (omental and subcutaneous), early morbidity, gastrointestinal hormones before and after test meal, duration of hospital stay, costs; Follow-up data will be obtained every 3 months in the first year, twice in the second year and once per year thereafter: weight, reduction in comorbidities, blood tests, gastrointestinal hormones before and after test meal, DEXA and quality of life.