Diet after gastric bypass: nutrition planning

Gastric bypass surgery is an effective procedure to achieve long-term weight loss and improved overall health. Following a specific diet after gastric bypass is crucial for a smooth recovery, weight loss, and avoiding any potential complications. The post-operative diet consists of five stages that progressively introduce various foods and textures to the stomach, enabling it to heal and adapt to surgical alterations.

Patients are typically put on a clear liquid diet in the beginning stage, which is then gradually transitioned to pureed, soft, and eventually solid foods. The final stage of the diet involves reintroducing solid foods into the meal plan, along with other foods and spices that were previously not allowed. It is important to follow the guidelines for each stage and avoid any foods that may cause discomfort or complications.

In this article, we will provide information about the diet and its stages, what to eat and what to avoid, how and why is it good to follow postoperatively, and lastly, how to meet the necessary nutrients with different diets, such as veganism.

Introduction to diet after gastric bypass

The post op diet for gastric bypass helps heal the stomach and the small intestine and contributes to weight loss by guiding you about what can you eat after a gastric bypass. Different foods and textures are gradually introduced to the stomach from liquids to solid foods. Each stage helps the body adjust to changes and prevent any potential discomfort or complications. This process helps the stomach and the small intestine rest and heal over time.

Along with restricting food intake, gastric bypass also decreases calorie and vitamin absorption. This occurrence calls for the aid of vitamin supplements. Gastric bypass patients have to take these supplements for life to prevent vitamin deficiencies that can affect their health negatively.

diet after gastric bypass

5 Stages of post op diet

It doesn’t matter which diet style you prefer such as vegetarian, vegan, etc., there are 5 stages of this diet. All gastric bypass diet stages help your body adjust to the changes made during the surgery. Underestimating the guidelines of gastric bypass diet stages can come with consequences, such as discomfort and complications. These stages are:

  • Stage 1: Clear liquid diet
  • Stage 2: Full-liquid diet
  • Stage 3: Pureed diet
  • Stage 4: Soft food diet
  • Stage 5: Solid food diet

All of these stages will last for 3 months in total and there is some restriction for the first month and during these 3 months. These certain restrictions will be lifted stage by stage after your surgery. Let’s have a look at what these temporary restrictions look like.

Avoid for the 1st month and start after a month:

  • Spices except for salt – you can have cinnamon and cocoa powder after a while
  • Citrus fruits – lemon, orange, etc.
  • Vegetables that can make you gassy
  • Coffee – decaf or not
  • Onion or garlic – cooked or not
  • Anything too hot or too cold 

Avoid the first 3 months and start after 3 months:

  • Raw vegetables and fruits
  • Legumes – lentils, chickpeas, etc.
  • Coffee – you can have decaf after a month
  • Starchy pasta, rice, bulgur, bread, barley, etc.
  • Dried fruits
  • Whole red meat or beef
  • Nuts
  • Alcohol and smoking

Stage 1: Clear liquid diet

Stage 1 gastric bypass diet includes clear liquids and lasts about 10 days. During this time, you can have:

  • Broth (chicken, stock, vegetable)
  • Clear tea
  • Unsweetened and diluted juice
  • Protein water

You are not allowed to have dairy, spices except salt, or vegetables that can make you gassy, such as cabbages. So, if you plan to put cabbages in your veggie broth, think thrice. It may bring great discomfort.

You should also keep close track of your water intake. Of course, this is not only limited to this stage. You should be drinking 8 ounces of water a day, although it may not be easy to do the first few weeks.

Stage 2: Full liquid diet- a transitional period

Stage 2 gastric bypass diet is a transitional period that lasts 35 days. This stage will help you switch to a puree diet. You can start consuming dairy, provided they are lactosefree and/or lowfat. In this stage, you can have:

  • Soups with no cream or grains
  • Protein shake
  • Probiotic yogurt and/or shots
  • Kefir
  • Lactose-free or low-fat yogurt
  • Lactose-free/low-fat/plant-based milk

This stage is also the checkpoint where you are going to need to increase your protein intake. Your body prioritizes burning muscles to provide energy for the body. And you might feel fatigued because of it. To prevent and manage that, you will be getting protein shakes prepared with milk, provided it is either lactose-free and/or low-fat, or vegan kinds of milk such as oat, almond, soy, etc. You can have other dairies such as probiotic yogurt and kefir.

You can start having soups as long as they don’t include cream, onion, spices, garlic, or vegetables that can cause gas buildup. All it needs to be is blended well without any grains. Do not opt for soup mixes as they may include so many no-no ingredients. Go for homemade. If you wish to add potatoes and carrots to your soup, you can. Make sure you don’t put a lot of them or have them frequently.

Stage 3: Pureed diet

Stage 3 diet after gastric bypass is the pureed food phase. This stage will last 1 week. You will not be getting lean meats yet, but you will be getting other lean protein sources, such as eggs, lowfat soft cheese, and proteinrich vegetables like spinach, asparagus, etc. Overall, you will eat the following during this stage:

  • Fresh fruit juice without filtering
  • Eggs
  • Low-fat cheese
  • Zucchini
  • Carrot and potato — not often and not too much of them
  • Parsley
  • Green peas

It is recommended that you don’t consume carrots and potatoes too often and add too much of them to your pureed food. They contain fructose, sucrose, and glucose. These are sugars and they can affect your digestive system by causing dumping syndrome.

About the cheese, it is recommended that patients try to eat cheese the last 23 days of this stage. And on the last day, for breakfast, patients can try to cook their eggs along with cheese. If toleration is an issue, they can try again later.

During the 3rd stage, most patients experience a “bariatric plateau”. Meaning they experience a halt or stop in their weight loss. This plateau will be resolved within a week, so do not fret if you also experience it.

Stage 4: Soft-food diet- the second transitional period

Stage 4 diet for gastric bypass is the second transitional diet plan. You will be eating half puree and half solid, provided it is soft, as the stomach and the small intestine are still healing. This stage lasts about 1 week. You can now consume the following:

  • Lean meats — chicken, turkey, ground beef, fish, etc.
  • Ayran
  • Soft fruits — peeled
  • Eggs with cooked and peeled tomato

You can start eating lean meats, such as chicken, ground beef, and fish. However, you need to blend and chew them well. You can also start eating soft and peeled fruits, such as bananas, kiwis, etc.

Stage 5: Solid food diet

Stage 5 diet after gastric bypass is the part where you begin eating solid food, spices, and fibrous vegetables that you weren’t supposed to before! This stage usually starts after a month and lasts until after the 3rd month. In short, you can have:

  • All spices
  • Cauliflower
  • Cooked onion and garlic
  • Broccoli
  • Lettuce

During the 5th stage, you will be introducing foods gradually to your body. You can try one certain meal a day. You will learn what you can and cannot tolerate. If you can’t tolerate a certain food and it brings discomfort, try it again next week.

Yes, you don’t have to shred or blend your meats and vegetables anymore, but you still need to chew them well. While you are eating your meal, eat your protein first to make sure you get your protein. Otherwise, your stomach may not be able to take the food, and you might not get enough protein.

Your macros and calorie intake

For your diet after gastric bypass, a general guideline is to consume a diet that is high in protein, low in fat, and moderate in carbohydrates. A recommended calorie intake range for weight loss after gastric bypass surgery is typically between 8001200 calories per day.

The recommended protein intake is generally between 60100 grams per day. This goal can be achieved with lean meats, eggs, low-fat dairy products, and protein supplements. Protein is important for healing and repairing tissues, building and maintaining muscle, and boosting the immune system.

Your fat intake should be 30% or less of daily calories, which is around 2642 grams. You can get these from healthy such as nuts, seeds, olive oil, avocados, and fatty fish. It’s important to avoid high-fat foods as they can cause discomfort and may affect weight loss negatively.

The carbohydrate intake should be between 50100 grams a day. You can obtain it by consuming complex carbohydrates such as whole grains, fruits, and vegetables. These provide energy and necessary nutrients while also helping to maintain stable blood sugar levels.

Importance of vitamin and supplements intake

After gastric bypass surgery, it is important to use multivitamin supplements and mineral supplements for life to prevent nutrient deficiencies. Gastric bypass surgery involves altering the stomach’s size and digestive system, which can result in reduced absorption of vitamins and minerals.

Here are some of the reasons why using multivitamin supplements and mineral supplements for life is important after gastric bypass surgery:

  • They prevent nutrient deficiencies
  • They support bone health
  • They prevent anemia
  • They help maintain muscle mass
  • They support the immune system

Here is an exemplary diet plan for you

This diet plan after gastric bypass is only an exemplary one. If you have certain needs to be met, they will be altered accordingly. Let’s review:

Stage 1:

  • Breakfast: fruit juice
  • Snack (optional): vegetable juice
  • Lunch: broth
  • Snack: tea
  • Dinner: Broth
  • Snack: vegetable juice

Stage 2:

  • Breakfast: protein shake
  • Snack (optional): fruit juice
  • Lunch: soup and yogurt
  • Snack: fat-free milk
  • Dinner: soup and yogurt
  • Snack: fruit juice

Stage 3:

  • Breakfast: scrambled egg
  • Lunch: Green pea puree mixed w/ low-fat yogurt
  • Snack: protein shake
  • Dinner: Spinach puree mixed w/ low-fat yogurt
  • Snack: Sugar-free custard

Stage 4:

  • Breakfast: omlete and soft low-fat cheese
  • Lunch: fish, pureed zucchini, low-fat yogurt
  • Snack: protein shake
  • Dinner: turkey, pureed asparagus, low-fat yogurt
  • Snack: sugar-free fruit puree
gastric bypass diet portion size

Stage 5:

  • Breakfast: soft-boiled egg, cooked and peeled tomato, and olives
  • Lunch: tuna, steamed vegetables, and low-fat yogurt
  • Snack: homemade sugar-free fruit smoothie
  • Dinner: ground beef, green peas, and low-fat yogurt
  • Snack: protein shake

Why do some surgeons follow a different plan?

Everybody needs unique nutritional plans to help their bodies function the way they should. Normally, if there aren’t any underlying condition, such as certain vitamin deficiencies, allergies, or the ability to tolerate certain foods, the diet plan given to the patients are very similar to one another. In the presence of one or a few of these conditions, a different diet plan is prepared for the patient to keep them nourished and healthy.

Sometimes, due to religious reasons or other reasons such as preference or tolerance, some people might follow a vegetarian, vegan, pescatarian, or kosher diet. Some of these diets require close observation of nutrients and vitamins. It is important to keep up with the protein sources to lose weight and gain and preserve muscle tissue.

So, in order for you to get the necessary nutrients and vitamins with the diet you wish to follow, your healthcare provider will prepare a proper diet plan for you accordingly to your wishes.

(1) Bettini S, Belligoli A, Fabris R, Busetto L. Diet approach before and after bariatric surgery. Reviews in Endocrine and Metabolic Disorders. 2020;21(3):297-306. doi:

(2) Sherf Dagan S, Goldenshluger A, Globus I, et al. Nutritional Recommendations for Adult Bariatric Surgery Patients: Clinical Practice. Advances in Nutrition: An International Review Journal. 2017;8(2):382-394. doi:

(3) Parkes E. Nutritional Management of Patients after Bariatric Surgery. The American Journal of the Medical Sciences. 2006;331(4):207-213. doi:

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