The gastric bypass diet forms the most important part of your post-operative cure. Having undergone gastric bypass surgery to lose your obesity, your gastric surgeon will explain to you the post-operative adjustments you will have to make throughout life for a good prognosis post-surgery.

Besides a disciplined lifestyle and regular physical activity, what and how much you eat is crucial for success.

Since the stomach size has been drastically reduced to about 25% of its original capacity and a portion of the gastrointestinal tract bypassed, the most important of the post-operative adjustments will be your post-gastric bypass diet.

Your surgeon and dietician will give you the details of your diet and they will vary somewhat from center to center but they will broadly be along the guidelines explained below.

  • How much food you can eat?
  • What type of food you can eat?
  • How often you should eat?
  • Consistency of the food you eat.

Aim of the gastric bypass diet

The main goals after any bariatric surgery are to:

  • safely allow healing of the sutured or stapled lines, without putting a strain on them by the food you eat.
  • acclimatize you to eating small amounts of food.
  • maximize weight loss and increase the absorption of nutrients to avoid nutritional deficiencies.
  • maintain adequate hydration
  • to prevent vomiting and dumping syndrome.

Post-operative eating recommendations

  • Do not drink anything 30 minutes before the meals, during the meals, and 30 minutes after the meals.
  • Drink water and fluids slowly during the day between meals.
  • Have frequent six to eight small meals during the day instead of three regular meals as your stomach will be able to hold only a few ounces of food at a time.
  • Take small morsels at a time.
  • Chew your food well into a paste before swallowing. Solid unchewed food can block the newly made narrow opening between the stomach and the intestines.
  • Eat slowly. A meal could take anywhere around 30 minutes.
  • Do not drink carbonated beverages, as this will cause the stomach to bloat.
  • Do not smoke.
  • Do not drink alcohol.
  • Make sure your foods are high in proteins. Your goal should be to consume a minimum of 65 to 75 grams of protein a day through eggs, meats, fish, seafood, tuna, poultry, soymilk, tofu, cottage cheese, yogurt, and other milk products as and when permitted.
  • Avoid foods that contain fats and sugars.
  • After surgery, your body won’t be able to absorb enough nutrients from your food. You may need to take a multivitamin supplement every day for the rest of your life. They will essentially be multivitamins, iron, folic acid, calcium, vitamin D, and Vitamin B12 supplements. You will have to break the pills into small pieces and then swallow them.
  • Avoid simple sugars like ice creams, juices, candy, and soft drinks as these can cause dumping syndrome, which can result in dizziness, diarrhea, sweating, tremors, and a rapid heartbeat.

Phase-wise dietary guidelines after gastric bypass

This diet plan is periodically divided into four phases and can take up to 12 weeks before regular solid foods are started. The diet should be high in proteins and help train the “new” stomach to slowly adjust to eating solid foods.

This however varies from person to person depending on how your body accustoms to the changed eating pattern.

Phase one – liquid foods

Duration:  About one to two weeks.

Immediately after surgery, you will be given nothing by mouth for the first 2 to 3 days to allow for healing of the sutured or stapled linings. After 3 days, you will be given liquid and semi-solid foods, which should be at room temperature.

Hot foods will have an adverse effect on the raw operated linings of the stomach and cause reflux of food into the esophagus. Secondly, the foods that you eat should be nonspicy for the same reason.

What you can eat in phase one:

  • Soup without cream
  • Broth
  • Juices without sugar
  • Skimmed milk
  • Diet Jello (sugar-free gelatin)
  • Sip these liquids slowly and take only about 2 to 3 ounces at a time (about 1/3 rd of a cup or about 60 to 90 ml).

Phase Two – Pureed or grounded foods

Duration: Two weeks.

This phase allows you to eat foods that can be ground or pureed well into a uniform consistency without having any solid pieces in them. If there is more than one type of food, choose those that blend well with each other. The end result should be a paste or a thick liquid.

This phase starts after a few days only after the foods of phase one have been tolerated well.

What you can eat in phase two:

  • Soft fruits without skin like apples, pears, watermelon, and bananas. Ensure all the seeds and the skin have been removed before grinding the fruits.
  • Soft vegetables like potatoes, yams, carrots, and green beans. Make sure to boil first before grinding. Remove skin and seeds.
  • Lean meats like chicken, turkey, and fish. Remove skin and ground well into a pulp.
  • Yogurt
  • Egg whites
  • The above-pureed foods can be blended with an appropriate liquid medium such as water, nonspicy gravy without fat, skimmed milk, broth, or juice without sugar.

Phase three – Soft semi-solid foods

Duration: Eight weeks or as recommended by your doctor.

Phase three foods are foods that are soft enough to be mashed with your fork or spoon. Examples include:

  • Finely minced chicken (not red meat)
  • Cooked fish
  • Soft fruits
  • Cooked peeled vegetables
  • Cooked, not fried, eggs
  • Skimmed milk
  • Low-fat sugar-free yogurt
  • Sugar-free jello
  • Low-fat cheese

Phase four – Low-fat and sugar-free solid foods

These foods are started about eight to ten weeks after surgery. At this time, you can start eating firm foods without grinding them. By trial and error, you can eat foods that you can tolerate.

Just remember to chew your food well into a paste before swallowing and eat very slowly. You can start eating red meat and fruits with skin. Add a new food one at a time to see how well you tolerate it.

Foods to avoid after gastric bypass

You should avoid certain foods and beverages throughout life post gastric bypass.

  • Bread
  • Popcorn
  • Sodas and other aerated drinks
  • Tough meats
  • Seeds and nuts
  • Dried fruits
  • Fibrous vegetables such as broccoli, celery, cabbage, and corn
  • Granola
  • Olives
  • Whole milk
  • Fried foods

The gastric bypass diet, if followed well, will help in a quick postoperative recovery and ensure success in your weight loss goal.

Long-term dietary guidelines months and years after surgery

Over time, you will be able to increase the variety and consistency of foods in your diet. You may still be unable to tolerate some foods such as red meats, chicken, bread, and high-fiber fruits and vegetables.

Stay focused on low-fat, low-sugar, and low-calorie foods, and continue to count your calories every day. Aim for 1500 calories every day.

Stay well hydrated, and drink at least 2 liters of water or non-caloric fluids daily, unless contraindicated.