Pre & Post Gastric Bypass Diet|Foods to Eat & Foods to Avoid after Gastric Bypass Surgery

Gastric Bypass Diet

Gastric bypass surgery is a very popular surgical procedure to ensure fast weight loss. It is a scientific procedure of preventing weight gain by limiting the capacity of the stomach. The doctors divide the stomach in two sections – a smaller pouch and a larger pouch. The food that is eaten enters the smaller pouch and thus, one feels full much quickly. Therefore, the quantity of food that is eaten is way less than usual.

Gastric Bypass Diet

Pre-Gastric Bypass Diet

One, who has undergone the gastric bypass surgery, needs to follow a strict Gastric Bypass Diet in order to cope with the changes in eating habit, as well as to help in the healing procedure of the surgery. For this, a dietician will help you in planning the diet chart. He/she will recommend a diet that will –

  • Prevent the stomach from getting stretched too much
  • Help you to lose weight
  • Help you to prevent gaining weight
  • Support you to adjust with the limited amount of food consumption
  • Prevent the complications and side effects of the surgery.

Post Gastric bypass surgery, the period of first three months is very crucial. Usually, liquid diets are given in the beginning in order to prevent dehydration that a surgery might result in as a side effect; as well as to contribute in the healing of the stomach. What you will be recommended to eat or drink will differ from one stage to another after a Gastric Bypass Surgery. How swiftly you can switch from one stage to the next, depends on how fast your body is healing or responding to the change after gastric bypass surgery.

Post-Gastric Bypass Diet

Before we get into the diet recommended after the Gastric Bypass Surgery, it is a must to mention that pre-operative gastric bypass diet is equally important. This too includes liquid diet that helps in reducing the amount of fat stored around the spleen or liver. For about a week or two, the doctor recommends low-fat or fat-free liquids, so that the problems like large liver or fatty liver are prevented. Otherwise, it can hinder the surgery. The foods to be eaten before gastric bypass surgery are:

  • Protein shakes
  • Unsweetened and non-caffeinated beverages
  • Vegetable juices
  • Broths and soups without any solid pieces
  • Lean meat
  • Vegetables
  • Thin cream of rice or wheat.

Foods to Eat After Gastric Bypass Surgery

Stage 1: Clear Liquid Diet

The dieticians and doctors always restrict the diet to only clear liquids for about a week immediately after Gastric Bypass Surgery. Even the amount of the liquid is restricted to only about 1 to 2 ounces per hour. Depending on the condition, response and recovery of the patient following gastric bypass surgery, the dietician will decide on the amount of the liquid to be consumed by the patient.

The liquids that can be given are after gastric bypass surgery are–

  • Broth or clear soup
  • Decaffeinated coffee or tea
  • Skimmed milk
  • Unsweetened juice (preferably fresh fruit juice)
  • Sugar-free popsicles or gelatine
  • Strained cream soup.

Along with these, drinking water is also very important in order to stay hydrated. Some surgeons may also want you to start your protein shakes within a few days of the gastric bypass surgery.

Stage 2: Pureed Foods

Within a week or so following gastric bypass surgery, the patient would be able to eat pureed, mashed up and strained foods. The food should be a thick paste or semi-liquid, with no pieces of solids inside. The foods that can be pureed at this stage are –

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

In order to blend them in a paste, the liquids that can be used as a base are –

  • Water
  • Broth
  • Unsweetened fruit juice
  • Protein shake
  • Skimmed milk.

At this stage, the quantity of food plays a very important role and also there should be a gap of about 30 minutes in between eating and drinking something. Depending on pureed and mashed foods and semi-liquids, this stage will continue up to the 3rd week post-gastric bypass surgery.

Stage 3: Soft Foods

In the 4th and 5th week after gastric bypass surgery, the patient should be reintroduced gradually to the usual diet, but starting with the soft foods. At this stage, the patient should be given about 64 ounces of liquid and about 60 to 70 grams of protein. This should be divided into 3 to 6 small portions throughout the day. High-quality lean proteins, fat-free dairy products and cooked vegetables are to be given at this stage.

Food to eat during this stage post gastric bypass surgery includes –

Protein and dairy products like –

  • Lean Chicken
  • Smaller Fish
  • Lean Turkey
  • Egg Whites
  • Non-Fat Cheese
  • Non-Fat Cottage Cheese
  • Yoghurt
  • Rice pudding
  • Porridge
  • Tofu.

Cooked vegetables and soft fruits like –

  • Potatoes
  • Green Beans
  • Carrots
  • Cauliflower
  • Squash
  • Tomatoes
  • Cucumbers
  • Avocados
  • Bananas.

The foods should be diced in very small pieces, cooked until very soft and easily chewable, ground or mashed or even steamed until very soft. The fruits should be ripe enough, so that they can be easily chewed and swallowed. Canned foods and fruits should be deseeded and skinned properly. Berries like blueberries, blackberries, raspberries and strawberries etc. can be eaten for a sweet treat.

Stage 4: Solid Foods

After about 8 weeks have passed following the Gastric Bypass Surgery Diet, gradually the patient can be given solid foods. Pieces should be small and easy to chew in the initial stage. Whether the patient is being able to tolerate the food or not, should be checked. Eating foods with a crunchy texture or eating spicy foods might be a problem at this stage post gastric bypass surgery.

Foods to Avoid After Gastric Bypass Surgery

Like the diet for most other surgeries, the diet after gastric bypass surgery too should have no fatty or spicy or rich foods and liquids. Any pressure on the stomach can be potentially threatening and upsetting for the success of the surgery. Moreover, there are certain foods that are seriously difficult to digest and therefore, should be avoided completely after gastric bypass surgery and these are –

  • Foods with Little or No Nutritional Value: Pastries, chips, candy, pretzels, popcorn, rice cakes as well as fried and fast foods as well as highly sweetened foods.
  • Dry Foods: Nuts and seeds, granola, dry fruits, cereal, whole grains.
  • Fibrous Fruits and Vegetables: Grapes, stringy or fibrous vegetables, like broccoli, celery or cabbage.
  • Meats and Fatty Fish: Beef and pork, tough meats or meats with gristle, shellfish.
  • High Fat Food: Sausage, butter, bologna, hard cheeses and whole milk.
  • Bread, rice, pasta, beans.
  • Carbonated beverages and alcohol.


Along with following the stage wise diet plan, the eating and avoiding the prescribed foods after gastric bypass surgery, you need to also maintain a proper chewing and eating habit. Eat in small portions, chew properly every bite for about 15 seconds and also have a gap of about 30 minutes between your eating and drinking regime to obtain the best possible outcome of gastric bypass surgery.

Also Read:

Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:August 2, 2017

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