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Should I follow a plant-based diet after bariatric surgery?

By NJBC Registered Dietitians | January 11, 2022

Patients often ask if plant-based diets are a safe and healthy option after bariatric surgery. This can be a challenging question as there isn’t a one size fits all answer. Plant-based diets often eliminate all or some animal products and may increase the consumption of carbohydrates and decrease protein intake. After bariatric surgery, protein is essential to maintain lean body mass and for optimal health and weight loss. So should you or can you follow a plant based diet after weight loss surgery? Our answer is yes, as long as you’re getting the required nutrients. Here are some things we want you to consider:


Reaching your protein goals after gastric sleeve, bypass or revision surgery requires a significant amount of planning and preparation with a plant-based diet. Following a vegetarian/ vegan diet will be more difficult  in reaching  protein goals than a flexitarian diet. For patients interested in cutting back on meat and increasing their plant-based intake, a flexitarian diet along with a few animal products will offer variety and help you reach your weight goals in a safer way.

Fiber and digestion 

People who consume a plant based diet tend to eat more vegetables and are generally getting more fiber.  While fiber is important for healthy digestion and feeling fuller longer, for patients who have had gastric bypass, fiber can be more difficult to digest and lead to bloating and discomfort. 


Iron is a nutrient that also becomes difficult to get if you are on a vegan or vegetarian diet. Although iron can be supplemented, taking iron supplements may cause constipation in some people.  

Now that you’ve considered the implication of protein, fiber and iron, let’s take a look at some more information on the various plant-based diets below. 

Vegan Diets

Vegan diets must be very carefully planned to avoid nutrient deficiencies such as iron, calcium, vitamin B12, and zinc. Carbohydrate intake may also be higher when following a vegan diet and this should also be carefully monitored following bariatric surgery. Since a vegan diet completely eliminates all animal products including honey, wine or beer that use animal products as clarifying agents, products tested on animals or items made from fur or leather; the main sources of protein in the vegan diet are seeds, nuts, beans, peas, lentils and legumes. Tofu, seitan, soymilk, beans and peas are some common vegan protein substitutes. 

RELATED: Plant Based Burgers

Vegetarian Diets

Patients considering a vegetarian diet want to exclude all flesh foods (such as meat, poultry, wild game and seafood). To reduce meat intake while ensuring an adequate daily protein intake, a well-planned vegetarian diet can include some animal proteins - possibly dairy, eggs or seafood (pescatarian) along with vegetables, fruits, whole grains, legumes (beans, lentils, peas), nuts and seeds.

Flexitarian Diets

Some patients opt for a flexitarian diet as it’s essentially what it sounds like -- a flexible diet. You might eat meat occasionally, but for the most part it’s not typically included daily in your diet. This can help take the pressure off sticking to the diet/lifestyle labeled as vegan or vegetarian. 

Whether you’re considering a vegan, vegetarian, flexitarian or any other plant-based diet, it’s important to choose one that allows for a healthy amount of protein and to know what each diet entails to determine what’s right for you.

If you have questions about the plant-based diet you’re on or are considering one, make an appointment to meet with your dietitian to ensure you are getting adequate protein pre and postoperatively.

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