Bariatric surgery: Surgery on the stomach and/or intestines to help a person with extreme obesity lose weight. Bariatric surgery is an option for people who have a body mass index (BMI) above 40. Surgery is also an option for people with a body mass index between 35 and 40 who have health problems like type 2 diabetes or heart disease.
There are two basic types of bariatric surgery -- restrictive surgeries and malabsorptive/restrictive surgeries. Restrictive surgeries work by physically restricting the size of the stomach and slowing down digestion. Malabsorptive/restrictive surgeries are more invasive surgeries that, in addition to restricting the size of the stomach, physically remove parts of the digestive tract, interfering with absorption of calories. An example of restrictive surgery is adjustable gastric banding also called lap band surgery . Stomach banding is the process of placing a synthetic band around the upper portion of the stomach. It works by creating a small "pouch" at the top of the stomach just below the esophagus, thus dramatically reducing the amount of food that can be eaten. The size of the opening to the stomach determines the amount of food that can be eaten. The size of the opening can be controlled by the surgeon by inflating or deflating the band through a port that is implanted beneath the skin on the abdomen. The band can be removed at any time.Another restrictive surgery is the sleeve gastrectomy. This procedure generates weight loss solely through gastric restriction (reduced stomach volume). The stomach is restricted by stapling and dividing it vertically and removing more than 85% of it. The stomach that remains is a narrow tube or sleeve, which connects to the intestines. The restricts the amount of food the stomach can hold, as well as removing the portion of the stomach that generates Ghrelin, the hormone that causes hunger. The procedure permanently reduces the size of the stomach. The procedure is performed laparoscopically and is not reversible.
In contrast to gastric banding, gastric bypass (sometimes referred to as roux-en-Y gastric bypass) is a permanent reduction in the size of the stomach. Gastric bypass is the most common type of weight loss surgery. It makes up about 80% of all weight loss surgeries in the U.S., and combines both restrictive and malabsorptive approaches. The proximal portion of the stomach is used to create an egg-sized pouch that is connected to the intestine in a location that bypasses about 2 feet of normal intestine. The amount of food that can be eaten is limited by the size of the pouch and the size of the opening between the pouch and the intestine.