Weight-loss surgery alters the body's digestive process by limiting the amount of food the stomach can hold and/or by limiting the absorption of nutrients. The most common procedures are restrictive, malabsorptive or a combination of both procedures. Restrictive procedures reduce the amount of food the stomach can hold, but don't interfere with the body's normal digestion of food and nutrients. Malabsorptive procedures bypass most of the small intestine so that fewer calories and nutrients are absorbed. Combined procedures restrict food intake as well as the amount of calories and nutrients the body absorbs.