Surgery is the most severe of the recommended treatments for obesity. Bariatric surgery is reserved for cases of severe obesity that have been resistant to all other methods of weight loss and weight control. There are two basic types of bariatric surgery (also known as gastrointestinal surgery), each with a different purpose.  The risks for both are similar, as are the prospective results and outcome.   Restrictive Weight Loss Surgery   The first type of bariatric weight loss surgery is 'restrictive'. It includes the well-known 'stomach stapling'. The purpose of restrictive surgery is to restrict the amount of food that can be eaten at one time. Doctors create a small pouch at the top of the stomach that holds about one ounce of food, with a small opening at the bottom to hold food in the pouch and cause a feeling of fullness. After the surgery, a patient can eat no more than 3/4 cup to a cup of well-chewed bland food at a time without becoming nauseous. The intent of the surgery is to reduce the amount of food eaten by restricting the amount of food that can be eaten at once.   Variations of restrictive surgery include 'lap banding', in which the pouch is created by wrapping a silicone band around the upper part of the stomach. Since there is no need to cut into the stomach or intestine, the complication rate is lower than in standard restrictive surgery, and the recovery period is shorter.   The second type of bariatric surgery for weight loss is the malabsorptive variety. These are the more common type of surgery for treatment of obesity. The most well-known of the procedures is the gastric bypass. The purpose of gastric bypass and other types of bypass surgery is to prevent the effective absorption of nutrients from food eaten by 'bypassing' most of the intestine in the food's path through the body. The malabsorption results in significant weight loss and a reduction of appetite.   The possible side effects of gastric bypass surgery include:   Chronic diarrhea Stomach ulcers Foul-smelling stools and flatulence Risk of nutritional and micro-nutritional deficiencies Dumping syndrome - symptoms include faintness, fainting, nausea, sweating and diarrhea after eating   Patients seeking bariatric surgery are evaluated by a medical professional for suitability for the surgery. Candidates include those who are at least 80-100 pounds overweight, and who have shown little success with traditional weight loss methods. In additions, patients who have other physical problems which require weight loss may be candidates.   If you're considering weight loss surgery, you must realize several things: 1. The risks of surgery are serious. 2. You will require lifelong medical supervision after the surgery 3. You will still need to make lifestyle and dietary changes. 4. Many health insurance plans will not cover it.   Be sure that you choose a surgeon experienced in bariatric techniques, and that you will be provided with full physical and emotional support before, during and after the surgery.