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Why Do Some People Regain Weight After Bariatric Surgery?

sharma-obesity-bariatric-surgery21Although bariatric surgery is by far the most effective treatment for severe obesity, it is not a magic bullet and there are a significant number of patients, who either fail to lose a significant amount of weight or ultimately regain most of their weight.

In a paper published in Obesity Surgery, we conducted an in-depth review on the issue of post-surgical weight regain.

Following an initial screen of 2,204 titles and review of 1,437 abstracts, we found only 16 studies with meaningful information on this issue.

These studies included seven case series, five surveys and four non-randomized controlled trials, with a total of 4,864 patients for analysis.

There were a number of methodological issues with these studies as they varied widely in terms of duration and quality of follow-up, definitions of surgical failure or weight recidivism, as well as the actual surgical procedures, all of which had important implications for the interpretation of the data.

Thus, for example, inconsistent definitions of exactly what constitutes “excessive” weight regain or “insufficient” weight loss makes it virtually impossible to determine even exactly how often this treatment can be considered to have “failed”. (Remember, it is always the treatment that fails the patient and never the patient who fails the treatment!).

Nevertheless, it is clear that post-surgical weight regain is highly multi-factorial (like obesity itself), involving both patient and surgery related factors.

Overall, we identified five principle aetiologies representing nutritional indiscretion, mental health issues, endocrine/metabolic alterations, physical inactivity and anatomic surgical failure, each of which I will discuss in upcoming posts.

There is no doubt that the issue of post-surgical weight regain requires a systematic approach to patient assessment focusing on contributory dietary, psychologic, medical and surgical factors.

Edmonton, Alberta
Karmali S, Brar B, Shi X, Sharma AM, de Gara C, & Birch DW (2013). Weight Recidivism Post-Bariatric Surgery: A Systematic Review. Obesity surgery PMID: 23996349




  1. Hi Dr. Sharma, thanks for this post. Having treated numerous patients with weight regain post bariatric surgery, a critical issue is that there are underlying metabolic glitches that surgery cannot ‘cure’ – such as MC4R malfunction, MSH deficiency due to POMC conversion issues, and unfortunately, the surgery itself along with the prescribed diet and exercise plan often results in VERY HIGH ghrelin levels and significant leptin suppression (post RYGB) which most studies do not examine – we need to be look at hormone levels pre-and post surgery to better understand the underlying metabolic cause of the problem in the first place because the very same metabolic issue will reappear years after surgery, and often the surgery and subsequent restrictive diet with exercise adds another issue in patients who in particular still have the ghrelin secreting tissue – I have measured ghrelin levels as high as 2400 in post RYGB patients who have regained nearly all the weight they initially lost post surgically. It’s not uncommon to see this pattern, in fact I have yet to see a patient with these issues who did not have measurable hormone imbalances (alpha-MSH, NPY, ghrelin, leptin)… These conditions are actually medically treatable although few physicians are looking at their patients metabolic labs and applying specific treatment to balance these hormones. The last thing I would recommend to these patients is yet another diet…..

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  2. I forgot to mention that the studies are failing to examine LONG TERM hormone changes – yes short term improvements do certainly occur as they also do with dieting, and insulin resistance reverses with surgery – but long-term ‘defense of body weight’ hormone settings are observed clinically in post bariatric patients years out from surgery, similar to those seen post dieting. Additionally, the core underlying metabolic issue that provoked the insulin resistance is not ‘cured’ by diets or surgery. I urge physicians to begin to look deeper into their patients’ metabolic picture both pre and post surgery.

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  3. In Science, 30 August 2013, are a study and a perspective editorial on a topic which in itself is not related, but an underlying mechanism may be.

    The pieces are on how the ongoing demands of poverty can lead to bad choices. The mechanism is that when people are dealing with an extremely demanding task or situation it is rather like an athletic performance (example given is cheetah dashing) and that the performance itself is so demanding that there simply is not enough remaining self-control to deal well with other demands so choices can be poorly made.

    This led me to think about several things: how people tend to approach weight loss — often trying to make three large changes simultaneously (healthier diet which also promotes a healthier microbiome), caloric restriction, and increased exercise. Obviously, all three are needed but I have to wonder if some people — perhaps many — would have better success if the steps were added one at a time with weeks getting used to each so that each step was no longer an unusual demand before adding another. It also made me wonder if for some people who use a surgical approach that perhaps the demands of healing wind up blow away the other attempted changes if too much is being introduced all at once for self-control to be optimized.

    Finally, 1. given the study
    Gut Microbiota from Twins Discordant for Obesity Modulate Metabolism in Mice
    in Science 6 September 2013
    and the nutritional conditions (healthy diet) which allowed the flora associated with thinness to flourish, and 2. given the multitude of benefits of exercise in terms of things like inflammatory control I wonder if perhaps dieting (caloric restriction) or surgery should come after nutritional changes and exercise addition both have sequentially been firmly in place long enough to become normal for the individual when possible.

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  4. I hope Dr. Sharma as my comment was not given free – and I think we both know why you take at least the informations on world wide level with you.

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