Gastric ring. Coloured X-ray of a section through the abdomen of a 51-year-old obese patient with a gastric band (narrowing, centre), showing normal functional transit of the upper gastrointestinal tract (black). Gastric bands are used to treat obesity. The band is placed around the stomach near its upper end, restricting the amount of food a patient can eat and helping weight loss. This procedure is carried out as part of bariatrics, the branch of medicine that deals with obesity.