Purpose: Gastric bypass is a type of surgery in which the stomach is reduced in size by one of several methods. This smaller stomach is then reconnected or bypassed to the small intestine. Having a gastric bypass can help speed weight loss by making it difficult to eat too much food at one time and to feel satisfied after very small meals.

After a gastric bypass, the volume the new, smaller stomach can hold is reduced from about 1 quart to about 1 ounce, or 2 tablespoons. Over time, the stomach pouch will stretch until it can hold 4 to 8 ounces, or about 1/2 to 1 cup, at a time. The size of the opening created between the stomach and small intestine is smaller, too&emdash;roughly 1/4 inch wide&emdash;which slows the rate at which food is emptied from the stomach into the small intestine.

Gastric bypass is usually performed only after many other methods of weight loss have been tried and failed. However, the surgery is not an end in itself. It is important to work closely with a physician and registered dietitian (R.D.) to start a program of new eating habits to ensure that weight loss is safe and successful. A regular, simple exercise program and psychological support are often recommended to create a better self-image and a whole new attitude to food.

Nutrition Facts
The gastric bypass diet is designed to bring about significant weight loss. Learning new eating habits and following the diet correctly will help to maintain this weight loss over time. In general, the gastric bypass diet includes foods that are high in protein, and low in fat, fiber, calories, and sugar. Important vitamins and minerals are provided as supplements.

Protein is the nutrient that the body uses to build new tissue. It is important to get enough protein right after surgery, to make sure that wounds heal properly. Over the long term, protein in the diet will help preserve muscle tissue, so that weight can be lost as fat instead. Foods like lean red meat or pork, chicken or turkey without the skin, fish of almost any type, eggs, and cottage cheese are high in protein and low in fat.

Sugary foods include candy, cookies, ice cream, milkshakes or slushes, soda pop, sweetened juices or gelatin, and most desserts. The gastric bypass diet is low in sweet and sugary foods for three reasons. First, these foods are high in calories and fat. Even in small amounts, they could make weight loss difficult. Second, eating sweet or sugary foods promotes "dumping," a reaction which can occur after the gastric bypass operation. Experiencing the unpleasant symptoms of dumping syndrome may limit the desire to eat sweet foods. Finally, most sweet and sugary foods don't provide many vitamins or minerals for the calories they take up&emdash;and since calories are so limited on the gastric bypass diet, it is important that every food contribute its fair share of nutrients.

Fat may be difficult to digest after gastric bypass surgery. Too much fat delays emptying of the stomach and may cause reflux, a back-up of stomach acid and food into the esophagus that causes heartburn. Fat may also cause diarrhea, nausea, or stomach discomfort. High-fat, fried foods and fatty meats are common offenders.

Fiber, found in foods like bran, popcorn, raw vegetables, and dried beans, is also limited on the gastric bypass diet. There is less space in the stomach to hold these bulky foods, and less gastric acid available to digest them. Some kinds of fiber could get stuck in the pouch itself, or block the narrow opening into the small intestine. Do not take any fiber pills or laxatives without the advice of a physician.

Vitamins & Minerals are an important part of the gastric bypass diet. Since the diet allows only small amounts of a limited variety of foods, it may be difficult to get enough vitamins and minerals from food alone. Deficiencies can develop in a matter of months. Iron, folate, vitamin B-12, and calcium are the nutrients most affected. Most physicians require their gastric bypass patients to take a multivitamin/mineral supplement.

The Gastric Bypass Diet
The gastric bypass diet unfolds in several stages, from "liquids only" to small meals of soft, high-protein foods. Meals on the new menu will be much smaller than normal, and the foods eaten must be very smooth in texture. On all stages of the diet, it is especially important to drink enough water, and to take vitamin and mineral supplements as prescribed.

1. Clear Liquids -- The first stage of the gastric bypass diet, clear liquids (meaning beverages that you can almost see through), usually lasts for a day or two after the operation. The clear liquid diet starts with sips of water, and then allows foods like sugar-free juice, diet gelatin, boullion or clear broth, and flat (no fizz) diet soda in small amounts, usually 2-3 ounces at a time.
2. Low-Fat Full Liquids -- If no problems are experienced with clear liquids, the gastric bypass diet advances to high-protein liquids like diet Carnation Instant Breakfast^TM, Ensure^TM, or Sustacal^TM. This stage of the diet is started before discharge from the hospital and lasts for 1 to 2 weeks. Most patients also begin taking a chewable multivitamin/ mineral supplement at this stage.
3. Soft/Purée Diet -- The physician will indicate when it is time to advance to the soft or purée diet. Some patients are able to start this diet after they have been out of the hospital for about two weeks. Others may need to wait longer. The purée diet includes very soft, high-protein foods like scrambled egg, low-fat cheese or cottage cheese, or blenderized lean meats like tuna fish, chicken, or pork. Some patients find it more convenient to use strained baby foods. It is important to make sure that all foods are puréed or extremely soft and smooth in texture.
4. Regular Diet -- The regular diet starts about 8 weeks or later after gastric bypass surgery. While this diet includes all 5 food groups, it is important to start with high-protein foods, like lean meats or milk, at every meal. Each meal or snack should be small, with liquids consumed in between meals. Ask a dietitian for advice on planning an individualized regular diet pattern.

This material does not cover all information and is not intended as a subsitute for professional care. Please consult with your physician on any matters regarding your health.