The gastric bypass diet is designed for people who are recovering from gastric bypass surgery to help them heal and change their eating habits. Your doctor or a registered dietitian can help you with a gastric bypass diet by guiding meal planning.

A gastric bypass diet specifies what type and how much food you can eat at each meal. Closely following your gastric bypass diet can help you lose weight safely.

The gastric bypass diet has several purposes:

  • To allow the staple line in your stomach to heal without being stretched by the food you eat
  • To get you accustomed to eating the smaller amounts of food that can be digested comfortably and safely in your smaller stomach
  • To help you lose weight and avoid gaining excess weight
  • To avoid side effects and complications

Diet recommendations after gastric bypass surgery or other weight-loss surgery vary depending on the type of surgery, where the surgery is performed and your individual situation.

Most commonly, the gastric bypass diet has four phases to help you ease back into eating solid foods. How quickly you move from one step to the next depends on how fast your body heals and adjusts to the change in eating patterns. You can usually start eating regular foods with a firmer texture about three months after surgery.

After gastric bypass or other weight-loss surgery, you must pay extra attention to signs that you feel hungry or full. You may develop some food intolerances or aversions.

Phase 1: Liquid diet
You won't be allowed to eat for one to two days after gastric bypass surgery so that your stomach can start to heal. After that, while you're still in the hospital, you start a diet of liquids and semisolid foods to see how you tolerate foods after surgery.

Foods you may be able to have on phase 1 of the gastric bypass diet include:

  • Broth
  • Unsweetened juice
  • Milk
  • Strained cream soup
  • Sugar-free gelatin

During phase 1, sip fluids slowly and drink only 2 to 3 ounces (59 to 89 milliliters, or mL) at a time. Don't drink carbonated or caffeinated beverages. And don't eat and drink at the same time. Wait about 30 minutes after a meal to drink anything.

Phase 2: Pureed foods
Once you're able to tolerate liquid foods for a few days, you can begin to eat pureed (mashed up) foods. During this two- to four-week-long phase, you can only eat foods that have the consistency of a smooth paste or a thick liquid, without any solid pieces of food in the mixture.

To puree your foods, choose solid foods that will blend well, such as:

  • Lean ground meats
  • Beans
  • Fish
  • Egg whites
  • Yogurt
  • Soft fruits and vegetables
  • Cottage cheese

Blend the solid food with a liquid, such as:

  • Water
  • Fat-free milk
  • Juice with no sugar added
  • Broth
  • Fat-free gravy

Keep in mind that your digestive system might still be sensitive to spicy foods or dairy products. If you'd like to eat these foods during this phase, add them into your diet slowly and in small amounts.

Phase 3: Soft, solid foods
With your doctor's OK, after a few weeks of pureed foods, you can add soft, solid foods to your diet. If you can mash your food with a fork, it's soft enough to include in this phase of your diet.

During this phase, your diet can include:

  • Ground or finely diced meats
  • Canned or soft, fresh fruit
  • Cooked vegetables

You usually eat soft foods for eight weeks before eating foods of regular consistency with firmer texture, as recommended by your dietitian or doctor.

Phase 4: Solid foods
After about eight weeks on the gastric bypass diet, you can gradually return to eating firmer foods. You may find that you still have difficulty eating spicier foods or foods with crunchy textures. Start slowly with regular foods to see what foods you can tolerate.

Avoid these foods
Even at this stage after surgery, avoid these foods:

  • Nuts and seeds
  • Popcorn
  • Dried fruits
  • Sodas and carbonated beverages
  • Granola
  • Stringy or fibrous vegetables, such as celery, broccoli, corn or cabbage
  • Tough meats or meats with gristle
  • Breads

These foods are discouraged because they typically aren't well tolerated in the weeks after surgery and might cause gastrointestinal symptoms. Over time, you may be able to try some of these foods again, with the guidance of your doctor.

A return to normal
Three to four months after weight-loss surgery, you may be able to start returning to a normal healthy diet, depending on your situation and any foods you may not be able to tolerate. It's possible that foods that initially irritated your stomach after surgery may become more tolerable as your stomach continues to heal.

Throughout the phases
To ensure that you get enough vitamins and minerals and keep your weight-loss goals on track, at each phase of the gastric bypass diet, you should:

  • Keep meals small. During the diet progression, you should eat several small meals a day and sip liquids slowly throughout the day (not with meals). You might first start with six small meals a day, then move to four meals and finally, when following a regular diet, decrease to three meals a day. Each meal should include about a half-cup to a cup of food. Make sure you eat only the recommended amounts and stop eating before you feel full.
  • Take recommended vitamin and mineral supplements. Because a portion of your small intestine is bypassed after surgery, your body won't be able to absorb enough nutrients from your food. You'll need to take a multivitamin supplement every day for the rest of your life, so talk to your doctor about what type of multivitamin might be right for you, and whether you might need to take additional supplements, such as calcium.
  • Drink liquids between meals. Drinking liquids with your meals can cause pain, nausea and vomiting as well as dumping syndrome. Also, drinking too much liquid at or around mealtime can leave you feeling overly full and prevent you from eating enough nutrient-rich foods. Expect to drink at least 6 to 8 cups (48 to 64 ounces or 1.4 to 1.9 liters) of fluids a day to prevent dehydration.
  • Eat and drink slowly. Eating or drinking too quickly may cause dumping syndrome — when foods and liquids enter your small intestine rapidly and in larger amounts than normal, causing nausea, vomiting, dizziness, sweating and eventually diarrhea. To prevent dumping syndrome, choose foods and liquids low in fat and sugar, eat and drink slowly, and wait 30 to 45 minutes before or after each meal to drink liquids. Take at least 30 minutes to eat your meals and 30 to 60 minutes to drink 1 cup (237 milliliters) of liquid. Avoid foods high in fat and sugar, such as nondiet soda, candy, candy bars and ice cream.
  • Chew food thoroughly. The new opening that leads from your stomach into your intestine is very small, and larger pieces of food can block the opening. Blockages prevent food from leaving your stomach and can cause vomiting, nausea and abdominal pain. Take small bites of food and chew them to a pureed consistency before swallowing. If you can't chew the food thoroughly, don't swallow it.
  • Try new foods one at a time. After surgery, certain foods may cause nausea, pain and vomiting or may block the opening of the stomach. The ability to tolerate foods varies from person to person. Try one new food at a time and chew thoroughly before swallowing. If a food causes discomfort, don't eat it. As time passes, you may be able to eat this food. Foods and liquids that commonly cause discomfort include meat, bread, pasta, rice, raw vegetables, milk and carbonated beverages. Food textures not tolerated well include dry, sticky or stringy foods.
  • Focus on high-protein foods. Immediately after your surgery, eating high-protein foods can help heal your wounds, regrow muscle and skin, and prevent hair loss. High-protein, low-fat choices remain a good long-term diet option after your surgery, as well. Try adding lean cuts of beef, chicken, pork, fish or beans to your diet. Low-fat cheese, cottage cheese and yogurts also are good protein sources.
  • Avoid foods that are high in fat and sugar. After your surgery, it may be difficult for your digestive system to tolerate foods that are high in fat or added sugars. Avoid foods that are fried and look for sugar-free options of soft drinks and dairy products.

Gastric bypass and other bariatric surgery can result in long-term weight loss. The amount of weight you lose depends on your type of weight-loss surgery and the changes you make in your lifestyle habits. It may be possible to lose half, or even more, of your excess weight within two years.

The gastric bypass diet can help you recover from surgery and return to enjoying many of the healthy foods before surgery. And remember that if you return to unhealthy eating habits after weight-loss surgery, you may not lose all of your excess weight, or you can eventually regain any weight that you do lose.

The greatest risks of the gastric bypass diet come from not following the diet properly. If you eat too much or eat food that you shouldn't, you could have complications. These include:

  • Dumping syndrome. This complication occurs most often after eating foods high in sugar or fat. These foods travel quickly through your stomach pouch and "dump" into your intestine. Dumping syndrome can cause nausea, vomiting, dizziness, sweating and eventually diarrhea.
  • Dehydration. Because you're not supposed to drink fluids with your meals, some people become dehydrated. You can prevent dehydration by sipping 48 to 64 ounces (1.4 to 1.9 liters) of water or other low-calorie beverages throughout the day.
  • Nausea and vomiting. If you eat too much, eat too fast or don't chew your food adequately, you may become nauseated or vomit after meals.
  • Constipation. If you don't follow a regular schedule for eating your meals, don't eat enough fiber or don't exercise, you may become constipated.
  • Blocked opening of your stomach pouch. It's possible for food to become lodged at the opening of your stomach pouch, even if you carefully follow the diet. Signs and symptoms of a blocked stomach opening include ongoing nausea, vomiting and abdominal pain. Call your doctor if you have these symptoms for more than two days.
  • Weight gain or failure to lose weight. If you continue to gain weight or fail to lose weight on the gastric bypass diet, it's possible you could be eating too many calories. Talk to your doctor or dietitian about changes you can make to your diet.
Oct. 08, 2011