Bariatric surgery in the treatment of morbid obesity is associated with long-term weight-loss and decreased overall mortality. Long-term results have been reported for laparoscopic gastric bypass procedures but the long-term results of laparoscopic sleeve gastrectomy are yet unavailable. As sleeve gastrectomy is a rapid and less traumatic procedure with good short-term results of weight loss and resolution of comorbidities, the investigators initiated a prospective randomized two-center study comparing laparoscopic sleeve gastrectomy (LSG)with laparoscopic gastric bypass (LGB) in the treatment of morbid obesity. Study hypothesis: As sleeve gastrectomy is less traumatic, easier and faster to perform compared with gastric bypass,LSG could become the procedure of choice to treat morbid obesity if the long-term results of weight loss and resolution of comorbidities are comparable with laparoscopic gastric bypass.

In addition to comparing the outcomes between sleeve gastrectomy and gastric bypass, the study project includes a PET trial conducted in Turku. The objectives of this PET study are to measure effect of obesity on food-stimuli mediated brain activation response and on hormones affecting both feeding and energy balance. In the second part the same variables are studied after bariatric surgery: either laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass. In addition the effect of weight loss due to bariatric surgery on glucose uptake and free fatty acid metabolism is measured. The objective is also to study whether less invasive sleeve gastrectomy is as beneficial in terms of weight loss and co-morbid diseases as more invasive Roux-en-Y gastric bypass and to compare the risk factors between these two surgical procedures. Regional glucose uptake and free fatty acid uptake in myocardium, skeletal muscle, subcutaneous fat, visceral fat, pancreas, liver and brain are studied with PET at baseline before bariatric surgery and post-operatively on the 3rd month. Changes in body fat distribution, in ectopic fat and fat content of key organs are investigated with magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS). Brain reward system response to food stimuli is assessed using functional MRI (fMRI) and white and grey matter volumes using diffusion tensor imaging (DTI).

The study consists of 80 morbidly obese adults, BMI ≥ 40 kg/m2 or if there is additional risk factor BMI ≥ 35 kg/m2. From these subjects, 40 are further studied with positron emission tomography (PET) and magnetic resonance imaging (MRI). In addition functional MRI (fMRI) will be performed for 40 subjects. For fMRI, a control group is recruited consisting of 20 lean and healthy subjects. Subjects are physically examined and anthropometric data are measured along with blood sampling.

Inclusion Criteria:

• BMI > 40 or BMI > 35 with a comorbidity associated with obesity
• Age 18 - 60 years
• Failed prior effective and controlled conservative treatments of morbid obesity

Exclusion Criteria:

• BMI > 60
• Difficult psychiatric conditions or lack of co-operation
• Difficult eating disorder (binge eating, bulimia etc.)
• Alcohol abuse
• Gastric ulcer

Patients rederred to three tertiary referral hospitals (Turku University Central Hospital, Vaasa Central Hospital and Peijas Hospital)for treatment of morbid obesity