Why is long-lasting weight loss so hard?

Losing weight is not easy. Not at all. But keeping it off is even harder. This is not new knowledge, but it is only recently that we have started to find out why it’s so hard to keep it off. Last year, I was working with some colleagues on a meta-analysis that evaluated different strategies for keeping weight off after a period of rapid weight loss using a very low calorie diet (<1000 kcal/d). We evaluated different types of diets (low GI, high protein, and so on) and supplements, exercise and finally anti-obesity drugs.

What we found was pretty depressing: none of the strategies were very effective at helping people keep the weight off. This much we were able to conclusively prove.

This got me thinking about how the body defends against weight loss. I concluded that there are at least three types of primary defenses against weight loss, all of them powerful and hard to dodge for anyone wanting to lose weight long-term. Moreover, the defenses operate according to the rubber band principle: the more weight you lose, the more defense activation, and hence weight regain, you are likely to experience.

First, once weight loss occurs the body will increase circulation of appetite increasing hormones and peptides, such as ghrelin (increases hunger) and leptin (increases satiety). Sure, you can override this cognitively, at least for a while, but you are basically swimming upstream from now on. It’s doable, just not very easy.

The second line of defense is called adaptive thermogenesis. This means that your body goes into calorie saving mode once you have shed some weight, and you will now burn a lot fewer calories during both rest and exercise. This reduction in metabolism is a lot lower that what we would normally expect as a result of having a lighter body.

The third line of defense is behavioral relapse into old habits. Some habits are formed early in life and are manifested in the brain. By losing weight you needed to change your old eating and exercise habits and form new ones. But those “highways” in the brain didn’t just go away, they are still there. And we are indeed creatures of habit, and after a period of fighting those first two defenses, those old habits can easily make a comeback when you feel tired and stressed.

And there also appear to be more defenses, not least psychological and emotional ones. One such example is that many overweight individuals identify with having extra pounds, usually established already in childhood. This means that they are used to a looking heavier than others. Once they lose weight, some individuals will struggle to identify with their new appearance, and consciously or not, they can can feel uncomfortable and regain for that reason, no matter how much they want to appear thinner.

My suspicion is that children who grow up overweight will have a harder time losing weight that adult-onset weight gainers for this very reason, since adult-gainers do not identify with being overweight to nearly the same extent.

The highly visual nature of obesity could in fact be one of the reasons it is so hard to treat long-term, at least with current reactive methods, such as drugs, diets and exericse.

I can understand if you feel a bit depressed reading this but in order to make real progress we have to understand why we have been failing for so long. Now we at least know a bit more about what does not work and why. I say that is at least partial progress. Real tangible progress will happen when we find methods that do not trigger these defenses in the same way or perhaps even avoid them altogether.

If you feel particularly nerdy and want to read the meta-analysis we did, please see Johansson K, Neovius M, Hemmingsson E. Effects of anti-obesity drugs, diet and exercise on weight loss maintenance after a very low-calorie diet or low-calorie diet: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr 2014;99:14-23. This paper was published open-access meaning that there is no fee for downloading it.


Ps. I will be holidaying for 2 weeks now, have a great summer everyone! Ds.

Bild 2013-05-31 kl. 09.27 #2

Why this blog?

Bild 2013-05-31 kl. 09.27 #2

I guess it’s part excitement and part frustration behind my decision to start communicating much more directly with real people interested in obesity and weight loss, and not just other academics and media. Let’s start with the frustration and then round off with the happy bits.

The lack of progress in both prevention and treatment outcomes is quite frankly staggering. Sure, the epidemic appears to be slowing down in more affluent segments of the population, but it is still more or less a runaway train in poorer areas of the US and Europe, and this also goes for countries in the middle of the nutrition transition, such as China and India. There are in fact very few places in the world where the epidemic is not doing very well. This is a public health failure of monumental proportions.

Despite this, most of the obesity experts continue to advocate more of the same tired old strategies, i.e. increased dietary control and exercise, and the outcomes are very predictable: more failure.

Then the experts seemingly got desperate and started to drastically scale up the use of bariatric surgery with minimal follow-up afterwards, as a kind of advanced quick fix. This very large increase in bariatric surgery volumes is a bomb waiting to explode if you ask me, since the safety of such drastic procedures are far from fully understood. A review I am working on with former student Filippa Juul has so far identified 32 separate nutritional deficiencies after bariatric surgery, some of them quite serious. And this is just one type of safety concern.

Another major source of frustration is the almost total lack of balance in the media. Every day they keep pumping out the same tired fad diets, or similarly ineffective measures. And on the next page you can read up on recipes for all kinds cakes and sweets, complete with glossy photographs and smiling photoshopped models. It’s quite absurd, but we apparently fall for it, and so they keep doing it.

The media is nothing if not cynical when it comes to weight loss, and it has now basically gotten to the point where public health nutrition and lifestyle advice is largely controlled by the media. These are some of the biggest frustrations for me as an obesity academic.

So, what are the happy bits? Well, just over a year ago, I started to become very interested in some of the deeper underlying psychological and emotional reasons behind overweight and obesity. And what I have discovered so far has got me pretty excited. I guess I feel a little like Howard Carter when he was exploring the unknown parts of the pyramids.

If you are anxious to read more in-depth information right now you can read a conceptual review paper I just published (Hemmingsson E. A new model of the role of psychological and emotional distress in promoting obesity: conceptual review with implications for treatment and prevention. Obesity Reviews, 2014, epub 16 June).

I am expecting to publish many posts on the topics covered in the review, for example how the very earliest years of our lives continue to affect our health as adults. I genuinely think that this type of information can be a concrete help for anyone wanting to lose weight permanently.

I actually think we are getting close to a genuine breakthrough in how we help people lose weight that actually works long term, and also in terms of preventing new cases of overweight and obesity. Sure, much more research needs to happen before the epidemic is confined to the history books. And that is why I go to work each day. Stay tuned of you want to find out more.



Erik Hemmingsson

Welcome to Holistic Obesity


Welcome to Holistic Obesity, a popular science blog about how we can solve one of the greatest health challenges of the 21 century: obesity. As scientists we have failed miserably with both treating and preventing obesity for many decades now, and things need to change. It’s time to stop scratching the surface and delve deeper into the many psychological and emotional aspects of weight control, that we are only just starting to understand. We need a holistic approach to achieve lasting weight loss, or I believe we will continue to fail.

During the last 12-18 months, I have been fortunate to gain some insight into this fascinating new area of obesity research, and this is why I decided to start this blog. I want to share these new insights with the world, and with you. My hope is that this will not only improve quality of care for overweight individuals, but also help relieve some of the stigma, shame and discrimation. Welcome.

Dr Erik Hemmingsson, Obesity researcher, Stockholm, Sweden