Gastric bypass diet: What to eat after the surgery
Medically reviewed by Drugs.com. Last updated on Oct 3, 2022.
A gastric bypass diet helps people who are recovering from sleeve gastrectomy and from gastric bypass surgery — also known as Roux-en-Y gastric bypass — to heal and to change their eating habits.
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.
The gastric bypass diet is designed to:
- Allow your stomach to heal without being stretched by the food you eat
- Get you used to eating the smaller amounts of food that your smaller stomach can comfortably and safely digest
- Help you lose weight and avoid gaining weight
- Avoid side effects and complications from the surgery
Diet recommendations after gastric bypass surgery vary depending on your individual situation.
A gastric bypass diet typically follows a staged approach 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 about three months after surgery.
At each stage of the gastric bypass diet, you must be careful to:
- Drink 64 ounces of fluid a day, to avoid dehydration.
- Sip liquids between meals, not with meals. Wait about 30 minutes after a meal to drink anything and avoid drinking 30 minutes before a meal.
- Eat and drink slowly, to avoid dumping syndrome — which occurs when foods and liquids enter your small intestine rapidly and in larger amounts than normal, causing nausea, vomiting, dizziness, sweating and diarrhea.
- Eat lean, protein-rich foods daily.
- Choose foods and drinks that are low in fats and sugar.
- Avoid alcohol.
- Limit caffeine, which can cause dehydration.
- Take vitamin and mineral supplements daily as directed by your health provider.
- Chew foods thoroughly to a pureed consistency before swallowing, once you progress beyond liquids only.
For the first day or so after surgery, you'll only be allowed to drink clear liquids. Once you're handling clear liquids, you can start having other liquids, such as:
Liquids you can have during stage 1:
- Unsweetened juice
- Decaffeinated tea or coffee
- Milk (skim or 1 percent)
- Sugar-free gelatin or popsicles
After about a week of tolerating liquids, you can begin to eat strained and pureed (mashed up) foods. The foods should have the consistency of a smooth paste or a thick liquid, without any solid pieces of food in the mixture.
You can eat three to six small meals a day. Each meal should consist of 4 to 6 tablespoons of food. Eat slowly — about 30 minutes for each meal.
Choose foods that will puree well, such as:
- Lean ground meat, poultry or fish
- Cottage cheese
- Soft scrambled eggs
- Cooked cereal
- Soft fruits and cooked vegetables
- Strained cream soups
Blend solid foods with a liquid, such as:
- Skim milk
- Juice with no sugar added
After a few weeks of pureed foods, and with your doctor's OK, you can add soft foods to your diet. They should be small, tender and easily chewed pieces of food.
You can eat three to five small meals a day. Each meal should consist of one-third to one-half cup of food. Chew each bite until the food is pureed consistency before swallowing.
Soft foods include:
- Ground lean meat or poultry
- Flaked fish
- Cottage cheese
- Cooked or dried cereal
- Canned or soft fresh fruit, without seeds or skin
- Cooked vegetables, without skin
After about eight weeks on the gastric bypass diet, you can gradually return to eating firmer foods. Start with eating three meals a day, with each meal consisting of 1 to 1-1/2 cups of food. It's important to stop eating before you feel completely full.
Depending on how you tolerate solid food, you may be able to vary the number of meals and amount of food at each meal. Talk to your dietitian about what's best for you.
Try new foods one at a time. Certain foods may cause pain, nausea or vomiting after gastric bypass surgery.
Foods that can cause problems at this stage include:
- Carbonated drinks
- Raw vegetables
- Cooked fibrous vegetables, such as celery, broccoli, corn or cabbage
- Tough meats or meats with gristle
- Red meat
- Fried foods
- Highly seasoned or spicy foods
- Nuts and seeds
Over time, you might be able to try some of these foods again, with the guidance of your doctor.
A new healthy diet
Gastric bypass surgery reduces the size of your stomach and changes the way food enters your intestines. After surgery, it's important to get adequate nourishment while keeping your weight-loss goals on track. Your doctor is likely to recommend that you:
- Eat and drink slowly. To avoid dumping syndrome, take at least 30 minutes to eat your meals and 30 to 60 minutes to drink 1 cup of liquid. Wait 30 minutes before or after each meal to drink liquids.
- Keep meals small. Eat several small meals a day. You might start with six small meals a day, then move to four meals and finally, when following a regular diet, three meals a day. Each meal should include about a half-cup to 1 cup of food.
- Drink liquids between meals. To avoid dehydration, you'll need to drink at least 8 cups (1.9 liters) of fluids a day. But 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 small intestine is very narrow and can be blocked by larger pieces of food. 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.
- Focus on high-protein foods. Eat these foods before you eat other foods in your meal.
- Avoid foods that are high in fat and sugar. These foods travel quickly through your digestive system and cause dumping syndrome.
- Take recommended vitamin and mineral supplements. 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.
The gastric bypass diet can help you recover from surgery and transition to a way of eating that is healthy and supports your weight-loss goals. Remember that if you return to unhealthy eating habits after weight-loss surgery, you may not lose all of your excess weight, or you may 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. If too much food enters your small intestine quickly, you are likely to experience nausea, vomiting, dizziness, sweating and diarrhea. Eating too much or too fast, eating foods high in fat or sugar, and not chewing your food adequately can all cause nausea or vomiting after meals.
- Dehydration. Because you're not supposed to drink fluids with your meals, some people become dehydrated. That's why you need to sip 64 ounces (1.9 liters) of water and other fluids throughout the day.
- Constipation. A lack of physical activity and of fiber or fluid in your diet can cause constipation.
- Blocked opening of your stomach pouch. Food can 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, talk to your doctor or dietitian.