A gastric bypass diet is for people who are recovering from gastric bypass surgery to help them heal and change their eating habits.

Gastric bypass surgery is one of several weight-loss surgeries currently performed. The operation itself has undergone several modifications over the years. The procedure in use today is called the Roux-en-Y gastric bypass. It shouldn't be confused with other weight-loss surgeries, such as the biliopancreatic diversion with duodenal switch, which is a more aggressive surgery.

Your doctor or a registered dietitian will talk with you about the diet you'll need to follow after surgery, explaining what types of food and how much you can eat at each meal. Closely following your gastric bypass diet can help you lose weight safely.

Purpose

The gastric bypass diet has several purposes:

  • To allow your stomach to heal without being stretched by the food you eat
  • To get you used to eating the smaller amounts of food that your smaller stomach can comfortably and safely digest
  • To help you lose weight and avoid gaining weight
  • To avoid side effects and complications from the surgery

Diet details

Diet recommendations after gastric bypass surgery vary depending on where the surgery is performed and your individual situation.

A gastric bypass diet typically follows a staged approach to help you ease back into eating solid foods as you recover. 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 about three months after surgery.

After gastric bypass surgery, you must be careful to drink enough fluids to avoid dehydration, and to pay extra attention to signs that you feel hungry or full.

Liquids

For the first day or so after surgery, you'll only be allowed to drink clear liquids. Sip slowly and drink only 2 to 3 ounces (59 to 89 milliliters) at a time. Once you're handling clear liquids, you can start having other liquids, such as skim or low-fat milk.

Liquids you can have during stage 1:

  • Broth
  • Unsweetened juice
  • Decaffeinated tea or coffee
  • Milk (skim or 1 percent)
  • Strained cream soup
  • Sugar-free gelatin or popsicles

Pureed foods

Once you're able to tolerate liquids for a few days, you can begin to eat strained and pureed (mashed up) foods. During this 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 foods that will blend well, such as:

  • Lean ground meats
  • Beans
  • Fish
  • Eggs
  • Soft fruits and cooked vegetables
  • Cottage cheese

Blend solid foods with a liquid, such as:

  • Water
  • Skim milk
  • Juice with no sugar added
  • Broth

It's important that you don't eat and drink at the same time. Wait about 30 minutes after a meal to drink anything. Also 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.

Soft foods

After a few weeks of pureed foods, and with your doctor's OK, you can add soft foods — in the form of small, tender, easily chewed pieces — to your diet.

During this stage, your diet can include:

  • Ground or finely diced meats
  • Canned or soft fresh fruit (without seeds or skin)
  • Cooked vegetables (without skin)

Solid foods

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

Even at this stage, there are foods you should avoid because they may cause gastrointestinal symptoms, such as nausea, pain or vomiting.

Foods to avoid:

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

Over time, you may be able to try some of these foods again, with the guidance of your doctor.

A new healthy diet

Three to four months after weight-loss surgery, you may be able to start eating 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 diet

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

  • 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.
  • 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
  • Drink liquids between meals. 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. 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 food.
  • 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.
  • Focus on high-protein foods. Immediately after your surgery, eating high-protein foods can help you heal. 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 high in fat (such as fried foods, ice cream and candy bars). Look for sugar-free options of soft drinks and dairy products.
  • 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, raw vegetables, fried foods and carbonated beverages.
  • 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 likely need to take a multivitamin supplement every day for the rest of your life. 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.
Feb. 20, 2015 See more In-depth

Products and Services

  1. Book: The Mayo Clinic Diet