Gastrointestinal surgery for obesity, also called bariatric
surgery, alters the digestive process. The operations can be divided into
three types: restrictive, malabsorptive, and combined
restrictive/malabsorptive. Restrictive operations limit food intake by
creating a narrow passage from the upper part of the stomach into the larger
lower part, reducing the amount of food the stomach can hold and slowing the
passage of food through the stomach. Malabsorptive operations do not limit
food intake, but instead exclude most of the small intestine from the
digestive tract so fewer calories and nutrients are absorbed. Malabsorptive
operations, also called intestinal bypasses, are no longer recommended
because they result in severe nutritional deficiencies. Combined operations
use stomach restriction and a partial bypass of the small intestine.
