Bariatric surgery helps extremely overweight (severely obese) people lose weight and is used only after diet and exercise did not result in long-term weight loss. The surgery makes the stomach smaller, so it fills up with less food.

The most commonly done types of bariatric surgery include:

• Laparoscopic gastric banding. This makes the stomach smaller but does not change the connection between the stomach and the intestines. The surgery is done through several small incisions in the belly. A band placed around the upper part of the stomach creates a small pouch that fills quickly to make the person feel full.
• Roux-en-Y (say "roo-en-why") gastric bypass. This makes the stomach smaller. It also changes the connection between the stomach and the intestines. A section of the stomach is separated from the rest of the stomach to make a small pouch to hold the food a person eats. The doctor connects the stomach pouch to the middle portion of the small intestine. Because some of the intestine is bypassed, less food is absorbed.

After surgery, the person will not be able to eat very much at one time and will get full quickly. Stomach pain, vomiting, or diarrhea may occur if the person eats too much at one time or if the person eats foods that are high in fat or sugar.