Gastric bypass diet: covering all the before&after phases

This chapter consists of the gastric bypass diet in general, both pre-op and post-op. This diet is a nutritional program and it is designed to promote weight loss and weight management for people who plan to undergo and who have undergone gastric bypass surgery.

Diet before the gastric bypass is optional for the majority of patients. Some, however, may be required to follow this diet to make the surgery safer and easier to perform for them. Following a specialized diet plan after surgery is important for adequate nutrition and weight management. The gastric bypass diet is usually divided into multiple stages, where new foods and textures are gradually introduced to the diet. 

The gastric bypass diet can lead to substantial weight loss, better overall health and quality of life, and decreased risk of health problems related to obesity. 

Gastric bypass diet in two steps

Generally, there are two steps to a gastric bypass diet: preop diet for gastric bypass and postop diet for gastric bypass.

The pre-op diet prepares you physically for the surgery and mentally for the postop diet and post-op life. This diet is optional for most patients. In the case where there is a need for patients’ livers to be shrunk and their BMI to be lowered, they might be required to go through with this diet to make the surgery safer and lower any kind of risks.

The post-op diet enhances your recovery and treats the relationship between the patient and food. Of course, it’s not limited there. The post-op diet is essential for all gastric bypass patients. It promotes weight loss and healthy preservation of ideal weight and muscle mass. With this weight loss surgery, food intake and the absorption of calories and nutrients are decreased by 70%.

Gastric Bypass Diet

A brief guide to diet before gastric bypass

Diet before the gastric bypass is a 2week diet. This diet is mostly optional. If you want to mentally and physically prepare yourself for the surgery and your life after the surgery, you can go with it. In extreme cases where the patient needs to lower their BMI and shrink the size of their liver as a requirement for the bypass, it may seem necessary.

On this diet, you should avoid carbonated beverages, caffeine, excessive alcohol consumption, sugars, carbohydrates, saturated fats, and binge eating. You should increase your protein intake and eat fibrous vegetables. For the last 2 or 3 days, you should switch to a liquid diet. Protein shakes, broth, tea, sugar-free gelatins and popsicles, and skim milk are often preferred during this week.

With this diet, your calorie intake will be between 12001400. It is also important to stay hydrated in general. Do not forget to drink your 2 liters of water a day.

A brief guide to the diet following the surgery

Your diet after the surgery will go through  5 stages. As your recovery progresses, you will be getting more nutrients and more dense/solid foods.

First, you will start with a clear liquid diet. Then, to prepare for the pureed food, you will go through a semiliquid semipuree diet. Then comes the puree diet. As your stomach heals, it begins to tolerate more density and varieties of food and spices. After the puree diet, you will go through a semipuree semisolid diet. And finally, a solid diet.

During this diet, you need to drink plenty of water. And of course, due to the nature of this procedure, you are going to need to take multivitamin supplements and mineral supplements for life to avoid any nutrient deficiencies.

The utmost important case of vitamins in the bypass diet

Gastric bypass surgery modifies the digestive system and can lead to vitamin and mineral deficiencies if the patient does not follow the gastric bypass diet and care for their supplement intake.

The body needs vitamins and minerals for important functions and lacking them can lead to significant health issues. So, it is crucial to understand that you need to take your multivitamin and mineral supplements for life after gastric bypass surgery to mend for the unabsorbed vitamins and minerals that your body needs in other to promote weight loss and good health.

The important role of bypass diet on your weight loss journey

The gastric bypass diet plays an important role after the procedure. There is an unbreakable relationship between diet and gastric bypass surgery. The surgery without the diet can work only to an extent. And that is the best-case scenario. If you don’t follow a gastric bypass diet, you might face the risks of the surgery.

On the other hand, the diet has a lot of additional pluses after gastric bypass surgery. Not only does it promote a healthy recovery, but it also helps adapt to a healthier lifestyle. And since as a result of the surgery your nutrient absorption will be decreased, your diet will consist of nutrient-dense foods so that you do not lack any of the important nutrients, vitamins, and minerals.

Help your stomach to recover

Following a gastric bypass surgery diet can actually aid in the healing process of your stomach. Especially during the first month, your stomach needs lots of rest to heal. With a progressive diet, your stomach can have an easier time digesting food. As it heals, your stomach slowly begins to tolerate denser foods and various spices.

Adapting to a new lifestyle

Gastric bypass dietary guidelines are made to help you adapt to a healthier lifestyle. It will help you better your relationship with food, help you practice portion control, promote great weight loss, and help you maintain your goal weight in the long run.

Losing fat & preserve muscle

This diet consists of decreasing calories and increasing protein intake. You can gain muscle and maintain it for a long time with this diet. You will now be eating nutrient-dense foods such as lean meats and protein-rich fruits and vegetables.

With this diet, you will get enough amount of protein intake and way less carb intake. This way, you lose fat and preserve muscle. You may ask why and how. The body never prioritizes using fat stocks for energy. On top of that, if you are not consuming enough protein, your body will first burn muscles for energy, causing muscle loss. If you do, along with other necessary nutrients, your body will be obliged to burn fat for energy.

Finding natural alternatives to refined food

There are lots of alternatives to add to your food to replace refined food. Here is a list of things you can replace refined food with:

  • White bread, rice, pasta, etc. → Whole-wheat bread, brown rice, quinoa, etc.
  • Sugary snacks, sweets, chips → Fiber-rich fruits and vegetables
  • Processed meats, high-fat meats → Lean meats, legumes, tofu, etc.
  • Refined sugars, sweeteners, etc. → Honey, maple syrup, etc.
  • Butter, margarine → Avocado, nuts, olive oil, etc.

With these alternatives, you can have yourself a delicious meal or a snack just as satisfying!

Is the gastric bypass diet similar to the ketogenic diet?

While there are some similarities between gastric bypass and the ketogenic diet, they are not exactly the same.

Both diets focus on reducing carbohydrate intake and increasing protein and fat intake to promote weight loss. The gastric bypass diet is specifically prepared for people who have undergone gastric bypass surgery and who need different dietary guidelines from people who have not. The gastric bypass diet aims to ensure sufficient nutrient intake, promote weight loss, and prevent post-surgery complications.

A ketogenic diet is a dietary approach that involves increasing fat intake and decreasing carbohydrate intake, causing the body to go into a state of ketosis (a metabolic state where your body uses fat for energy instead of glucose). This brings the following question: Can a gastric bypass patient use the ketogenic diet? It is not prepared for patients who have undergone gastric bypass surgery, and it may lead to nutrient deficiencies for them.

In the end, while there are similarities between the two diets, a ketogenic diet for gastric bypass is strongly frowned upon. One should consult their healthcare provider to discuss the best dietary guidelines that can be followed for their individual needs and goals.

World cuisine suggestions after gastric bypass

Some love Indian food, some love Italian, and some love Japanese/Chinese food. The best news is, you can still have them after your gastric bypass surgery! However, you can only have dishes that do not collide with your dietary guidelines.

Let’s have a look at what meals you can have from various cuisines.


  • Buddha’s delight
  • Egg drop soup or hot and sour soup
  • Moo shu dishes (made with lean meat or vegetables and served with lettuce wraps instead of pancakes)
  • Steamed or boiled dumplings (filled with lean meat or vegetables)
  • Steamed or stir-fried chicken, beef, seafood, or tofu with vegetables
  • Steamed rice or noodles (in moderation, brown rice and whole wheat noodles if possible)


  • Edamame
  • Grilled chicken or fish dishes
  • Miso soup
  • Sashimi
  • Sushi rolls with vegetables


  • Chicken tikka masala
  • Lentil dal
  • Spinach and paneer cheese dishes
  • Tandoori chicken
  • Vegetable curry dishes


  • Eggplant parmesan (baked, not fried)
  • Bruschetta (small whole wheat bread)
  • Grilled calamari
  • Marina sauce
  • Minestrone soup (with moderately added whole wheat pasta)
  • Steamed mussels
  • Whole wheat noodles


  • Grilled or baked fish dishes
  • Greek salad with feta cheese
  • Grilled chicken or lamb dishes
  • Hummus with veggies
  • Lentil soup


  • Black bean soup
  • Grilled chicken or fish dishes
  • Guacamole with vegetables
  • Salsa with baked tortilla chips
  • Vegetable fajitas


  • Green papaya salad
  • Grilled chicken or fish dishes
  • Shrimp pad Thai
  • Tom yum soup
  • Vegetable stir-fry dishes


(1) 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: Link

(2) Zarshenas N, Tapsell LC, Neale EP, Batterham M, Talbot ML. The Relationship Between Bariatric Surgery and Diet Quality: a Systematic Review. Obesity Surgery. 2020;30(5):1768-1792. doi: Link

(3) Thomas JR, Gizis F, Marcus E. Food selections of Roux-en-Y gastric bypass patients up to 2.5 years postsurgery. Journal of the American Dietetic Association. 2010;110(4):608-612. doi: Link

(4) Masood W, Annamaraju P, Uppaluri KR. Ketogenic Diet. PubMed. Published 2020. Link

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top