Surgery may be a weight-loss option for patients who are severely obese and suffer from serious medical complications due to weight. There are two accepted surgical procedures for reducing body weight: gastroplasty and gastric bypass. Although these two procedures use different surgical methods, they both reduce the stomach to a pouch that is smaller than a chickens egg, drastically limiting the amount of food that can be consumed at one time. Surgery produces 25 to 35 percent reductions in weight over the first year and most of this weight loss is maintained five years after surgery. More importantly, the serious medical conditions that accompany extreme obesity improve significantly. Surgery is not without risk and should be performed by skilled surgeons who also provide patients with a comprehensive program for long-term weight control.

Limited gastric capacity and a narrow anastomotic gastrointestinal stoma necessitate certain dietary modifications particularly in the early post-operative period. Diet progression varies amongst health care professionals. A standardized GBP diet does not exist. Generally, most patients begin with a liquid diet due to the small, edematous gastric outlet. This phase of the diet may range from one day up to 6 weeks. Afterwards, pureed textures are introduced and the diet is slowly advanced to soft-textured foods by about 12 weeks. Small, frequent meals rich in protein are emphasized. Liquids are usually consumed between meals to allow greater intake of calories and protein with solid foods. Carbonated drinks may cause distension and discomfort from the carbon dioxide. Red meats, tough meats, breads and milk products may be difficult for some patients to tolerate. Until solid food intake is adequate, high protein liquid supplements such as sugar free Carnation Instant Breakfast (mixed with low lactose milk if necessary) are often recommended.

During the first six to 12 months after surgery, patients generally consume 900 to 1000 calories. Calorie consumption slowly increases due to a change in the pouch size and stoma size, gastric emptying rate and intake of solid food. Sugar and concentrated sweets are discouraged in order to prevent dumping syndrome. Because the pyloric sphincter is bypassed, simple sugar is dumped into the small intestine causing an increase in the osmotic load, thereby drawing fluid into the intestine leading to diarrhea, nausea, diaphoresis and abdominal cramps. The shunting of blood to the intestines and the perceived decrease in blood volume 30 minutes to one hour after a meal prompts many patients to lie down in an effort to improve cardiac output.

Gastric bypass patients generally lose 50%75% of excess body weight and are usually successful with weight maintenance.

The obese population, especially the morbidly obese, is increasing at an alarming rate in the United States. Weight loss programs have been found ineffective in this group. In an effort to improve the quality of life and decrease comorbidities associated with this patient population, gastric bypass surgery may be an option.