What is a Vegan Bariatric Diet? And photos of vegetables to the side of text.

What is a Vegan Bariatric Diet?

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Have you ever considered a vegan bariatric diet? Are you afraid that you have to compromise your ethics and stay with an omnivorous diet because you had bariatric surgery? If you want to follow a vegan diet and stay healthy after bariatric surgery, read on for the most important tips to follow. 

Reasons to Follow a Vegan Bariatric Diet

There are several reasons you may want to follow a vegan bariatric diet. First is ethical reasons. A vegan diet is rooted in ethical reasons. 

Definition of Veganism

According to the Vegan Society, “Veganism is a philosophy and way of living which seeks to exclude—as far as is possible and practicable—all forms of exploitation of, and cruelty to, animals for food, clothing or any other purpose; and by extension, promotes the development and use of animal-free alternatives for the benefit of animals, humans and the environment. In dietary terms it denotes the practice of dispensing with all products derived wholly or partly from animals.”

a toy cow, a toy pig, and a toy sheep standing next to each other with a green background

A second reason people decide to go vegan is for health reasons. A vegan diet can certainly be a very healthy diet. According to the Academy of Nutrition and Dietetics, vegetarian diets are associated with a reduced risk for cardiovascular disease, type 2 diabetes, high blood pressure, and cancer (reference). 

Even though the reduced risk of several chronic diseases are associated with a vegan diet it is easy to miss these health benefits by skipping vegetables, fruits, legumes, and whole grains in favor of fried food, vegan meat/cheese replacements, and sweets. Of course these fun foods can fit into your diet but should not be the main focus of your diet.

How to Follow a Vegan Bariatric Diet

So how do you follow a vegan bariatric diet? And how is a vegan bariatric diet different from an omnivorous bariatric diet?

Similarities of a Vegan Bariatric Diet and an Omnivorous Bariatric Diet

Let’s start with the similarities between a vegan bariatric diet and an omnivorous bariatric diet. Both diets need veggies, fruits, and whole grains every day. If you’re struggling with where to start this is a great place. 

Start with making sure to have these foods every day and then make the full jump to a vegan diet. You can even add foods in one at a time instead of all at once. Transitioning to a vegan diet from eating mostly meat and cheese with skimpy amounts of plant foods is more tricky.

Whether you are following a vegan bariatric diet or an omnivorous one you still need to take the recommended supplements. Vitamin and mineral absorption is altered and reduced after bariatric surgery so supplements are required. Risks of vitamin and mineral deficiencies are high after bariatric surgery as a result.

Your bariatric surgery program will monitor lab values and watch for other signs/symptoms of deficiency to individualize your supplements. Most often you will take a multivitamin with minerals (should contain iron) and calcium. Formulation of supplements vary so there are more or less pills you will need to take daily to meet micronutrient needs.

Both a vegan bariatric diet and an omnivorous one need adequate fluids to stay hydrated. This is challenging after bariatric surgery as most people do not tolerate gulping fluid and have to sip their fluids. Fluids to drink on a vegan bariatric diet are water, tea, infused water, broth, popsicles, flavored water, and even coffee. 

person chopping vegetables at a countertop

Differences in a Vegan Bariatric Diet and an Omnivorous Bariatric Diet

One of the main differences between a vegan bariatric diet and an omnivorous one is the protein foods. To meet protein needs after bariatric surgery patients are counselled to include meat, dairy, and eggs often. This is to make it easier to meet protein needs for patients. 

Plant options are often forgotten or never introduced as an option in a bariatric diet. Consume adequate protein by eating legumes, tofu, tempeh, seitan, nuts, seeds, soy milk, nutritional yeast, and even a faux meat option here and there. Include a variety of these foods at each eating occasion to get plenty of protein on a vegan bariatric diet. 

water with berries and mint soaking in it

Important Nutrients on a Vegan Bariatric Diet

After bariatric surgery there are several nutrients that you need to pay extra attention to. Protein, fiber, calcium, iron, vitamin B12, vitamin D, and vitamin B1 (thiamin) are monitored closely after bariatric surgery. These nutrients often take planning to make sure you’re getting the right amount after bariatric surgery whether you’re vegan or not.


There are many choices of foods to eat to get enough protein on a vegan bariatric diet. From tofu and tempeh to legumes and seitan there is an option for everyone. It is important to include high protein food at each meal and most snacks after bariatric surgery.

photo of cooked tempeh


Fiber only comes from plant foods so make sure to include lots of vegetables, fruits, legumes, and whole grains in your daily diet. Meeting fiber goals can often be easier on a vegan diet vs an omnivorous diet as all of the foods you are eating come from plants. Choosing less processed foods can make it more likely that you will get enough fiber.

Eating enough fiber is important to keep your heart healthy, help you have regular bowel movements, and to make sure you feel full long enough after eating.


It is nearly impossible to consume enough calcium after bariatric surgery from diet alone. After Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) surgery (the 2 most popular bariatric surgeries in the United States) you need 1200-1500 mg of calcium per day. This can come from food and supplements combined. 

Vegan sources of calcium include fortified plant milks (soy, pea, almond, coconut, etc.), tofu, sesame seeds, soy yogurt, broccoli, and collard greens.


It is also difficult to consume enough iron to avoid deficiency after bariatric surgery. Most people need 45-60 mg of iron supplements after RYGB and SG. You still get iron from the food that you eat, but supplements are still required for the vast majority of people after bariatric surgery-vegan or not.

Vitamin B12

On a vegan diet you need to supplement with vitamin B12 as this is only found in foods of animal origin. Even though there are some fortified vegan foods that contain vitamin B12 the supplement is still recommended to ensure a reliable daily dose. Vitamin B12 is recommended to be supplemented at 500 mcg per day after RYGB and SG.

Vitamin D

Another micronutrient that is challenging to get enough of after bariatric surgery is vitamin D. It is produced in our bodies in response to sunlight exposure. Unfortunately most people either don’t spend enough time in the sun or don’t have adequate sunlight present where they live. 

After RYGB and SG supplement with 75 mcg (3000 IU) of vitamin D per day. Individualization of this amount is based on lab values; it is very common for people to need even more after bariatric surgery. Vitamin D supplements are just as important for vegans as omnivores after bariatric surgery.

Vitamin B1 (Thiamin)

Thiamin requirements are much higher after bariatric surgery than the general population and risk of deficiency is high. It is not common for vegans who haven’t had bariatric surgery to be deficient in thiamin, but it is common after bariatric surgery. Take at least 12 mg of thiamin supplements daily after bariatric surgery.

Considerations at Each Stage of a Vegan Bariatric Diet

After bariatric surgery your diet progresses through different stages that change in type, texture, and volume of food. It will provide adequate fluid, protein, fat, and carbohydrate to allow you to lose weight, heal, and maintain lean body mass. 

Every bariatric program is different in what they recommend for their post-operative diet progression protocol. In general though it will likely have many characteristics that are similar to the following information. 

Clear Liquid Diet Stage

The initial diet phase after bariatric surgery is a clear liquid diet. This is usually a very short stage-just one to two days after your surgery. Your priority at this time is to work on hydrating yourself with water, herbal tea, broth, and infused/flavored water. 

Full Liquid Diet Stage

The second diet phase after bariatric surgery is a liquid diet. Drink some fluids for hydration (such as the ones described above) and some fluids that are providing calories. On a vegan bariatric diet your liquid diet may include soy milk, protein drinks, blended soups, and smoothies, etc.

photo of smoothies with berries and vegetables

Soft Diet Stage

After the liquid diet stage is often the pureed/soft diet phase. Continue to include liquid foods as it is easier to meet nutrition needs from liquids rather than solids. Some bariatric centers separate this into two separate stages and some just have one combined stage. 

Foods you may include on the soft/pureed diet phase may include tofu, legumes, soy yogurt, and soft vegetables and fruits. Make sure that you are able to comfortably meet your protein goals before adding vegetables and fruits to your meals. 

photo of scrambled tofu in skillet

Better tolerance of protein foods with a more fibrous/chewy texture such as seitan, tempeh, and faux meats may occur in the regular/solid food stage rather than the soft/pureed stage. Prepare these foods in a way that keeps them tender and moist, rather than tough or dry to increase tolerance. Sometimes mashing/pureeing them may be necessary to tolerate them in this diet stage.

Regular/Solid Food Diet Stage

After the soft/pureed diet stage you begin to incorporate more and more ‘normal’ foods on your regular/solid food diet stage. At this time you should continue to include a concentrated source of protein, vegetables, and fruits in your diet. You can now eat raw vegetables, fruits with peels, and nuts/seeds; make sure to chew well. 

Once you are able to eat adequate protein and include vegetables and fruits at meals, add grains and starchy vegetables. These are important parts of your diet as they provide fiber, vitamins and minerals, and satisfying texture to meals. 

2 meals with chickpeas, rice, avocado, broccoli, and green beans. tomatoes on the side

Pros and Cons of Following a Vegan Bariatric Diet

Choosing to follow a vegan bariatric diet has a wide range of positive benefits but it is also important to understand potential pitfalls or disadvantages. Sometimes you may get the impression that a vegan diet is perfect for everyone that if you just avoid all animal products in your diet you will have perfect health. This is far from the truth.

Vegan Does Not Always Equal Healthy

The fact is that vegans have health problems too. The cause of all disease is not diet and not all diseases can be cured and/or improved with diet. Following a vegan bariatric diet is not a guarantee of improved health.

Don’t incorrectly assume that a vegan diet is just automatically healthier than an omnivorous diet. This can lead to people not paying attention to what they are eating or having the attitude of ‘of course my diet is healthy – it’s vegan!’ It is absolutely possible that a vegan diet is not healthy, just like an omnivorous diet may not be healthy. 

Emphasis on high protein foods after bariatric surgery is common and as a result many people stick to a diet high in animal products. This often leads to consuming saturated fats in amounts that are larger than recommended for heart health. Choose more plant-based foods to meet protein goals to be more likely to eat less saturated fats and more fiber. 

Some of the nutritional benefits of following a vegan bariatric diet are that it is often higher in fiber and heart-healthy monounsaturated and polyunsaturated fat but lower in saturated fat.

Calorie Density

Following a vegan bariatric diet can often be low in calorie density which may be a positive thing or a negative thing. Many plant foods are low in calorie density and without proper education on what to eat many people can wind up undereating. On the other hand as portion sizes increase it can be a benefit to include more foods that are lower in calorie density to increase satiety/satisfaction from meals while still meeting weight loss goals.


A vegan bariatric diet may be more difficult to navigate as the proper support may be difficult to find. Many bariatric dietitians and doctors are not familiar with how to make a vegan diet work after bariatric surgery. This means that you may need to find some of your own information or seek out support from a dietitian outside of your bariatric center.

laptop computer on a table with pens, journals, and coffee

Open communication with your bariatric team and being honest about what you are doing with your diet after bariatric surgery is key to staying healthy. Even if your bariatric program doesn’t have a lot of experience with vegan diets they are there to help you and have your best interest in mind. Seek out your own information as needed but keep your bariatric team in the loop too. 

Finding your own information can be difficult as nutrition information available to the public is not always good advice to follow. My hope with this blog is to help those that are looking to follow a vegan bariatric diet find evidence-based information to use to help them stay healthy after bariatric surgery.


To close, following a vegan bariatric diet in a healthy way is a realistic, doable option. You may need additional education on which foods to include to meet protein goals, vegan options for vitamin and mineral supplements, and vegan foods for all of the diet stages following surgery. This may also be your opportunity to educate them with what you learn. 

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3 thoughts on “What is a Vegan Bariatric Diet?”

  1. I was morbidly obese when I became Vegan, and I did not lose weight because I was a junk food vegan. I liked how you mentioned that just because one is Vegan, doesn’t make them healthy. I’m having WLS in August and I my hope is to be WFPB Vegan.

    1. Ashley Krautkramer

      Hi Tonya,

      Yes-you are right! Whether or not you’re vegan you need to consider the health of your diet after bariatric surgery to make sure you are feeling good and meeting your goals.
      thanks for commenting!

    2. Hope you are doing well after your WLS Tonya. Give us an update if you can. I had mine on June 11, 2020 and have done well but struggling right now with snacking at night.

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