[Bariatric surgery: who, when and where?; an overview for the referring physician].

- Bariatric surgery is performed in patients with a body mass index (BMI) > 40kg/m2, or BMI > 35 kg/m2 with obesity-related comorbidities. The Roux-en-Y gastric bypass and sleeve gastrectomy are the most frequently used procedures.- On average, patients have lost 25-27% of their original weight 10 years after surgery.- Obesity-related comorbidities improve dramatically in many patients following surgery. The effect is most noticeable in patients with diabetes mellitus type 2 and obstructive sleep apnoea syndrome. - The prevalence of 30-day complications is < 5%. Mortality is < 0.2% in centres with a lot of experience. - Commonly occurring long-term complications of bariatric surgery include deficiencies, particularly of iron and vitamin B12, along with gallstone disease and sagging skin. - Specific complications can arise following Roux-en-Y gastric bypass, such as internal herniation and hypoglycaemia, and these are often not recognised.