Diets after Bariatric Surgery

Steph Wagner

August 3, 2022

Diets after Bariatric Surgery

A comparison of popular diets after weight loss surgery


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Why a diet after bariatric surgery?

Why would someone be looking at another diet after bariatric surgery? It would cause anyone to wonder!

Isn’t surgery the “last resort” and you wouldn’t need more diets? Would keto be necessary after weight loss surgery?

Part of the answer to this question is addressing expectations after weight loss surgery.  When someone wants to lose more weight after surgery, we also need to talk about what is most natural to their body. In terms of what  we tend to see for weight loss after Gastric Sleeve, Bypass, Duodenal Switch, SIPS/SADI or others.

Now that surgery has been utilized in treating obesity for a few decades, we have more data on post-op surgery patients. We do see “rebound weight” (regained weight) in patients which can be scary! Especially if the patient didn’t know that was part of the journey.

Not only do we see some rebound weight, we do see that less than 5% of patients will lose to a BMI of 25 (consider the healthy range on the BMI chart). Page 87 AND Pocket Guide to Bariatric Surgery. 

The GOOD news is that we see 90% of patients lose over 50% of their excess body weight. Bariatric surgery continues to be the most effective treatment for the disease of obesity.

Nonetheless, there is a honeymoon year after bariatric surgery and when this phase of the journey begins to wear off, patients do wonder what else they could try to lose more weight or lose rebound weight.

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What do most successful patients eat (and do)?

Another thing we have research to help us with is studying the habits of patients who have maintained their weight loss for years after surgery.

There are two studies I often reference with this information. One is the LABS-2 Post Operative Variables and Weight Change 3 Years after Bariatric Surgery. The other is a poster from a ASMBS meeting entitled Factors Distinguishing Weight Loss Success and Failure at 5 or more Years Post Surgery (click here to view the poster).

These studies show overlap in habits reported by successful patients. To summarize some of them patients reported:

They focused on protein first

Ate set meal times (instead of grazing)

Kept follow up appointments

Schedule daily movement

Ate at home more than eating out

Ate mindfully

Attended support groups

For a really fun blog series, check out the 10 Habits of Successful Bariatric Surgery Patients. 

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Comparing diets after bariatric surgery

With those things in mind (that rebound weight is normal, that 2% of post-op patients will reach a BMI of 25 and that successful patients are keeping post-op habits consistent) we will now look into popular and mainstream diets.

If you have really been interested in trying one of these approaches like keto or intermittent fasting, visit the full blog specific to each one linked below.

Some diets will conflict with bariatric surgery guidelines. Others can work with considerations in mind. My recommendation is to work with a bariatric dietitian. He or she will help you consider what is the best fit for your nutrition care after surgery, what you can sustain and what feels most natural to you.

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Popular Diets after Bariatric Surgery series

For more information on any one of these diets, click the image below for the blog (with audio option). I share the backstory of each plan, what it recommends, if there is research, how it may (or may not) work after surgery and other notes to consider.

If you’ve wondered about weight loss pills after Gastric Bypass or Sleeve, click here for a blog on that topic!


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4 thoughts on “Diets after Bariatric Surgery”

  1. What is the normal range of rebound weight gain after you hit goal? How do you know when you have reached the amount of weight your body is going to lose?

  2. Oh shoot! I was really hoping that you would address the NutriSystem diet as I see so many of those ads on FaceBook.

  3. I apologize there are so many diets I had the draw the line somewhere! From what I have researched, the meals are high in starchy ingredients than protein. I would be more comfortable with a bariatric surgery patient looking into Bari Box where the meals are portioned but focused on protein and bariatric guidelines compared to NutriSystem that is following more of a calorie focused approach, not necessarily focusing on protein. The NS website says the meals are balanced with carbs, protein and fat but I don’t see that as much in the menu options (for example the Grain Crusted Pollock with vegetables was 47 grams of carbohydrate, 22 grams of protein and 16 grams of fat).

  4. We just have statistics to tell us what we ‘tend to see’ based on what’s reported but it’s hard to really look into the future and know what that looks like for each person. Statistics show 10 year post-op data shows weight regain of approximately 20-25% is to be expected. (This is reported in the Academy of Nutrition and Dietetics Pocked Guide to Bariatric Surgery. I am hoping as we’ve learned more about in the last 10 years that number will improve). It has also been reported from the ASMBS that 2 years or more after surgery patients have shown a rebound of approximately 5% of their extra body weight. Traditionally patients lose the most in the first 12-18 months post-op so if someone is at a stall and less than 18 months post-op, it wouldn’t be assumed they were done losing. Truth be told, it’s possible to lose more weight not matter how long it’s been since surgery, but there is a natural gravitation to a ‘set point.’ At the end of the day we like patients to focus on the habits more than the scale and allow the body to level off where it feels best within the healthy lifestyle it’s been given. I hope that helps! It’s tricky!

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