Follow me on

Removing the Cause of Weight Gain Does Not Mean Weight Loss

One of the most common misconceptions about obesity management is that identifying and addressing a potential contributor to weight gain should automatically translate into weight loss – it does not!

As I pointed out in a recent post, when you identify and address the cause of weight gain – weight gain stops, and that’s usually it!

That many of us fail to recognize this rather simple principle, is again illustrated by a paper by Penner and colleagues published in the Journal of Joint and Bone Surgery, which found that successful ankle reconstruction surgery does not decrease BMI in overweight and obese patients.

According to their findings, the 145 patients with excess weight who underwent successful ankle replacement or ankle fusion, despite significant improvements in Ankle Osteoarthritis Scale (AOS) scores and increased physical activity scores, pretty much maintained their preoperative BMI levels at six months and one, two, and five years.

Based on these findings, the authors conclude that:

“Pain and disability are significantly reduced in overweight and obese patients after successful ankle replacement or fusion. Despite this, the mean BMI remains unchanged after the surgery, indicating that weight loss does not commonly occur following successful ankle reconstruction in this patient population. Obesity is likely attributable to factors other than limited mobility caused by ankle arthritis.”

Obviously, the authors assumed that if limited mobility caused weight gain, then increasing mobility should reduce it – that, however, is not what happens.

Rather, what they found, is exactly what I would expect – with regain of their mobility, patients stopped gaining weight – and that’s all.

Without a targeted obesity treatment strategy, there is indeed no reason to expect that these patients would now begin losing weight simply because their activity levels may now be somewhat higher than before. The few extra calories that they may perhaps now burn as a result of being more physically active would easily be compensated by an increased intake or other biological mechanisms that are there to ‘defend’ their current weight.

Thus, the observation that successful ankle surgery did not result in ‘spontaneous’ weight loss neither disproves nor proves that pain or disability may have contributed to weight gain in the first place – it probably did in some and probably did not in others.

Interestingly enough, I believe that this study also bears an important lesson for those attempting to address obesity at a societal level – even if we did know what exactly is driving the obesity epidemic – removing this cause does not necessarily mean everyone gets thinner – it just means that things may hopefully not get worse.

Berlin, Germany

ResearchBlogging.orgPenner MJ, Pakzad H, Younger A, & Wing KJ (2012). Mean BMI of Overweight and Obese Patients Does Not Decrease After Successful Ankle Reconstruction. The Journal of bone and joint surgery. American volume, 94 (9) PMID: 22552679



  1. That ankle surgery can result in arresting weight gain is a great outcome. One would think that knee and hip surgery could have similar results. Thanks for bringing this study to our attention!

    Did the study indicate whether percentage of muscle mass changed? Can we start to encourage a secondary focus on changes of muscle to fat ratio in future studies? Working muscle does a lot to ward off a number of ailments. It would be interesting to see how muscle mass changes as a result of successful joint operations, and for how long the change is sustained.

    Post a Reply
  2. Terrific blog, as it reminds us of what we should all know and frequently forget to tell our patients who are going for orthopaedic surgery, most commonly knee replacement. We forget to tell them that they may not lose weight, and in fact some can gain weight due to increased social activities and a resulting increased intake. I remind my patients of this fact, which (i think), helps them to remember the principles of organized eating habits, keeping a food diary and making better food choices. For the morbidly obese patients, I am sure that weight loss will help preserve their new knee (I am sure Arya has blogged on paper showing this before – yeah?). Great blog Arya, thanks. Sean

    Post a Reply
  3. Exactly right! People always act as if, “Well if you would JUST QUIT DOING THAT you’d be thin!” But that’s totally wrong. I “quit doing that” many years ago! I lost some weight. I lost some symptoms. But I’m still fat and I still have other symptoms regardless of what I eat or how much. The assumption people make in the social environment, that you are literally *every single day doing things to keep yourself fat* adds to prejudice greatly, in my observation.


    Post a Reply
  4. You see the same sort of thing in the literature concerning hypothyroidism. I gained 60 pounds, went from BMI 23 to 33. But I kept reading stuff that said hypothyroidism didn’t cause much weight gain, only about 10 pounds average. So I decided to try to find the medical research that was based on.

    It turns out that when you treat a hypothyroid person with thyroid hormones, they only lose about ten pounds. So reasoning backwards, that is all they must have gained due to the disease! As if euthyroidism should result in a large unintentional weight loss. Sheesh.

    Post a Reply

Submit a Comment

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