Bariatric surgery refers to a variety of surgical procedures designed to help people with severe obesity lose weight. These surgeries work by either limiting the amount of food the stomach can hold, causing malabsorption of nutrients, or by a combination of both gastric restriction or malabsorption. Common types of bariatric surgery include gastric bypass, sleeve gastrectomy, adjustable gastric band, and biliopancreatic diversion with duodenal switch.