Why It's So Hard to Keep the Weight Off

How Our Bodies Work to Regain Weight

happy overweight woman
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It's a problem as old as dieting itself: we lose weight, we gain it back.  We are blamed by others, but most of all by ourselves.  I've written about some of the tricks our brains play on us to get us to eat, but our brains are probably responding to something even more basic.

I've long been fascinated by how the body regulates weight. For 40 years I've been observing people lose and regain weight (including myself).

I try to follow people who lose weight over time to see what happens. Almost invariably, they gain back at least part of it, and all too often end up heavier than they started.  Long-term studies on weight loss are just as discouraging -- very few people seem to maintain substantial weight loss for five years (the standard for long-term weight loss).   People in a famous World War Two study of calorie restriction almost all ended up heavier after the study was over when they could resume normal eating (the average was 50% more body fat than when they started).

We know that following a low-carb way of eating definitely makes a difference in this equation.  It wasn't until I started meeting people in the low-carb community that I saw greater long-term success.  Even people that remain overweight are often able to keep off more weight than on other diets (and in a more stable way), but sadly it is not a magic bullet for everyone who wants to get to their dream weight.



To hear some people tell it, our weight is 100% under our conscious control, but it's long been crystal clear to me this this is simply not true. People who have been highly successful in many areas of their lives have been told that they lack willpower if they are overweight, and I do not believe it.

For one thing, the role of hunger is very often ignored when it comes to weight control! It seems as though this is about as basic a connection as it's possible to make (hunger leads to eating -- what a shock), but during discussions of weight regain the conclusion is always that "people go back to their old habits". Yeah, that old habit of eating when you are ravenous is a difficult one to shake, for sure!

Chemicals That Regulate Hunger

One advance of the last 10 to 15 years is the discovery of many of the mechanisms that regulate hunger. Hormones and peptides, including leptin, ghrelin, cholecystokinin, peptide PYY, and many more, have been investigated. Research published in the November 2011 issue of the New England Journal of Medicine (Long-Term Persistence of Hormonal Adaptations to Weight Loss), measured nine of these appetite-regulating substances that the body produces as participants lost ten percent of their body weight on a low-calorie diet, and then maintained their weight for a year (not everyone who started out in the study was able to accomplish this, but they measured the people who did).

What they found was that all nine chemicals they measured changed in response to the weight loss in the "hunger direction", and these changes persisted over the following year. Additionally, people reported feeling increasingly MORE hunger over this time, and that the same amount of food did not make them feel as satisfied by the end as it did before they lost the weight.  How long do these hormonal changes persist?  That research has not been done, but it most likely is at least for several years, judging by the experiences of dieters.

Energy Expenditure Plummets with Weight Loss

Another fairly dramatic change noted by the researchers is that people's energy expenditure (calories used) went down with weight loss and stayed down (people were encouraged to do 30 minutes of moderate exercise per day, but were given no other instruction). Partly this was due to a down-regulation of basal metabolism. Also, when people aren't getting enough to eat, they simply stop moving as much. The body is orchestrating a complicated coordinated response to get us to stop losing weight after a certain point, and then regain.  This makes total sense as a survival mechanism, but that is not much of a comfort to those who are trying to reach a healthy weight.

See: Evidence that Low-Carb Eating Lowers Energy Expenditure Less Than Other Diets

Is it a surprise to anyone that our bodies keep very close tabs on the food we ingest, and regulate it to a very fine degree? I think the reason that some folks are in shock over this is that eating feels voluntary, but the hungrier we are, the less control we have. Our bodies will even pull out the "emotional eating card" when we lose weight which encourages weight regain.

The Good News About Weight Loss

The good news is that it does not take a large weight loss to get most of the health benefits.  If an overweight person loses 5-10% of their body weight, they will get the vast majority of the benefits. This is perfectly doable for a substantial number of people (without excess hunger!) on a low-carb diet, and many people will obtain even greater losses.  In addition, a low-carb diet has its own health benefits apart from the weight loss.

Why Don't We Get This?

Even before we knew about the delicate dance of hormones and other chemicals our bodies use to regulate the amount of fat we carry, it was pretty clear that people rarely were able to maintain a substantial weight loss.  Obesity experts consider it common knowledge, and physicians who specialize in Obesity Medicine know that the unrealistic weight loss expectations of their patients can be an obstacle to long-term success.  It's frustrating to know that a modest weight loss maintained can be a huge boon to health, but that the lack of attaining a "dream weight" can derail the whole enterprise and cause their patients to give up.

However much the experts know about this, the word is absolutely not out to the general public.  Companies in the business of making money from helping people lose weight are certainly not going to broadcast this news!

I also think that this explains part of the reason why people who don't have a weight problem can't really understand those who do. They think about how when they've overeaten and they simply cut back and lose the three pounds they gained. The thing is, we all do that, within a few pounds. Our weight can fluctuate within a range fairly easily without undue stress.  What people who do not have a weight problem don't realize is that when our bodies go beyond that "comfort range" the experience is dramatically different.

One question is how people who lose large amounts of weight and keep it off are different those who regain. Partly it is probably simply the luck of the draw of individual variation, partly it may be getting a large amount of exercise (in the neighborhood of 60-90 minutes of exercise per day seems to help prevent weight regain), and partly it may be a certain level of obsessiveness and a bunch of time and energy to devote to the endeavor. But I would guess it almost certainly involves cutting some carbs (a friend I know who has successfully maintained a long-term weight loss realized after a chat that she did eat a low-carb diet, she just hadn't realized it). 

If are struggling to keep lost weight off, that's no time to give up on your exercise (and it's  a great time to start it if you haven't already), weigh yourself regularly, and keep your carb intake low.

Focus on Health

For me, one main moral of the story is to become happy with my body, and focus on health. A low-carb diet has stabilized by weight, reversed my body's progression towards diabetes, normalized my blood pressure and blood lipids, halted my food cravings and obsessions, and improved my energy levels and ability to concentrate. I'll take it!!

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