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Why Diet and Exercise is Not a Treatment for Obesity

Over the next little while, I will be taking a few days off and so I will be reposting some of my favourite past posts. The following article was first posted on Jun 20, 2011:

If going on a diet or starting an exercise program resulted in persistent weight loss,  we would not have an obesity epidemic.

Unfortunately, as anyone who has tried this knows, maintaining a significant degree of weight loss requires daily dedication, motivation and a limitless supply of will power – nothing short of developing a compulsive obsession.

As readers will recall, the biology of the post-weight loss state is nothing like the biology of someone who has never lost weight. There are countless ways in which the psychoneurobiology, energy physiology and metabolism in anyone who has lost weight are remarkably different from someone ‘naturally’ of that weight.

Simply stated, someone who was 150 lbs and has lost 20 lbs cannot hope to maintain that weight loss by simply eating the same amount of food or doing the same amount of exercise as someone who is ‘naturally’ a 130 lbs.

The 150 lbs person who has lost 20 lbs, to maintain their new 130 lbs, has to actually now live like someone who is ‘naturally’ a 110 lbs; just eating like someone who is 130 lbs but has never lost weight, will simply result in rapid weight regain.

This is why just cutting out a few ‘extra’ calories or walking a few ‘extra’ steps is not an effective or sustainable strategy for maintaining weight loss – for any clinically meaningful weight loss (when indicated) – we are looking at cutting hundreds of calories from the diet and adding hours of serious exercise per week – forever!

A comprehensive and fascinating overview of the fundamental changes that occur with weight loss to ultimately make sustaining this new weight an ongoing challenge, is discussed by Paul Maclean and colleagues from the University of Denver Colorado, in a paper just published in the American Journal of Physiology.

The authors provide a detailed synthesis of data from a wide range of weight loss studies that include studies in clinically overweight and obese adults, in diet-induced, polygenic animal models of obesity, and with dietary (non-surgical) interventions involving an energy restricted low fat diet.

The consistent finding from all such studies is that all individuals or animals in a post-weight-loss state face considerable ‘homeostatic pressure’ that aims to drive their weight back to initial levels.

The paper extensively discusses how changes in biological signals of fat stores (e.g. leptin) elicit profound metabolic and behavioural adaptations – a topic that I dealt with extensively in previous posts.

The key findings of increased hunger and appetite, reduced satiety and substantially increased ‘fuel efficiency’ have very real underlying biological drivers – drivers powerful enough to ultimately wear down even the most persistent dieter.

As the authors point out – persistent dieting is so difficult because it requires maintaining a remarkably large ‘energy gap’:

“Because both sides of the energy balance equation are affected after weight loss, the biological pressure to gain weight is a consequence of both increased appetite and suppressed energy expenditure.

During weight maintenance after weight loss, this energy gap reflects the magnitude of the daily burden that thwarts cognitive efforts to maintain the reduced weight.

Regardless of which side of the energy balance equation is most affected, the energy gap imparts a substantial pressure to eat in excess of the energy requirements.

The magnitude of the energy gap is greatest at the nadir weight after weight loss. Likewise, this energy gap does not dissipate with time in weight maintenance. Rather, studies in DIO (diet induced obesity) models indicate that the magnitude of the energy gap gradually increases the longer they maintain their reduced weight with an energy restricted diet .

The implications from these observations are that the biological pressures may strengthen with time and the amount of lost weight, gradually increasing their perceived influence.”

The paper also extensively discusses some of the lesser known metabolic adaptations to weight loss including profound changes in gut biology that enhance caloric extraction from food as well as alterations in liver function, skeletal muscle and fat tissue that promote weight regain.

While all of this may seem hopeless to readers, the authors actually end on the rather positive note that:

“… only by acknowledging that these homeostatic pressures emerge, we can proactively develop and implement regain prevention strategies to counter their influence. To ensure success, the regain prevention strategies will likely need to be just as comprehensive, persistent, and redundant, as the biological adaptations they are attempting to counter.”

Obviously, it is also important to note, that no ‘weight-loss strategy” actually addresses the many complex reasons why people may gain weight in the first place.

Whoever said that treating obesity was simply a matter of ‘eating less and moving more’ (ELMM) probably also believes that they can live forever by simply breathing less.

Burlington, Ontario

Maclean PS, Bergouignan A, Cornier MA, & Jackman MR (2011). Biology’s Response to Dieting: the Impetus for Weight Regain. American journal of physiology. Regulatory, integrative and comparative physiology PMID: 21677272


  1. I’m thrilled to have found your blog posts. This one is fascinating and the information you’ve provided will be put to good practice with my clients and students. Thank you Dr. Sharma! Great post. Enjoy your time off.

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  2. Arya, do you think this applies to pregnant women as well, who gain 20-30 lbs but perhaps have never had that extra weight prior to being pregnant?

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  3. Interesting post. A perfect weight loss strategy includes didication, patience and motivation. This leads to a perfect and healthy wieght loss. I also agree with this point. Mental health is very much important for weight loss strategy which leads to peaceful sleep and stress less mind, these all results in a healthy life without obesity. Thanks for the post. Thanks.

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  4. @Antigone: many factors can contribute to post-partumweight retention including changes in physical activity, depression, sleep deprivation and relationship issues.

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  5. Thank you for the interesting article. Having lost 150 pounds, the article’s point about the “nadir” inducing a raging screaming eating monster inside is quite true, unfortunately. Learning to tame the beast (or at least to live in relative harmony with it) is a life’s work, absolutely counterintuitive, but indispensible to sustaining the weight loss. Thanks again,

    ~~ kate

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  6. This is ridiculous. But the person who weights 150 might not “naturally” weigh that amount. They may have gained it unnaturally through over-eating, illness, etc. For example, I always weighed around 120 lbs up until 25, when I gained 20 lbs due to a pretty sedentary and unhealthy lifestyle. I wouldn’t say I was then “naturally” 140 lbs. I was always 120. I lost the 20 lbs through diet and exercise, then brought my diet back to normal, and now I”ve maintained my weight, give or take a lb or two, for the past five years. Are you saying that, because I gained 20 lbs, that somehow I am not always going to be naturally 140? This makes no sense!

    Also, human beings are not naturally obese. If they were, there wouldn’t be an obesity epidemic. And a lot of the obese or overweight people I know were not always 300lbs. They had a “normal” weight for years. My best friend was 130 lbs, or there about, up until a few years ago when she rapidly put on weight due to depression. She’s now 170, and trying to lose. Why would she now be naturally that weight? Can you explain to me how someone’s metabolism can change so drastically as to make them now be unable to be a “naturally” slimmer weight, because this just doesn’t seem right to me.

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  7. I agree with CB. This article is like saying Fast Food is natural, absurd. Most people in the World and the past were not overweight, why because they ate whole non processed foods and did mostly physical labor. Our bodies are designed to heal themselves if taken care of properly, so I would imagine, if we take care of our bodies by giving it what it needs through proper food with limits and physical exercise, then our bodies would naturally heal themselves. The reason most overweight people gain weight back is because of the diet mentality and the Great American Diet. I myself have lost and gain numerous times. I was always waiting to lose that last pound so that I could go back to eating what I was eating when I gained the weight. I am sorry to say it does not dawn on some of us, that is how we got there in the first place. With all the ads saying supper size and no real food education in schools, most people do not put 2 and 2 together and figure it out until all the weight comes back on. Most busy people are looking for convenience, and the fast food industry fits that bill. We are a society of mindless eaters and finding the easy way out mongers. We need to be educated and all food manufacturers need to look at the big picture of what is going on in this country…we are in a death trap and most of us are oblivious to the epidemic. So please don’t write articles that have no validity or merit and does not make sense to even the non medical person. You are taking hope away from us who are striving to make our lives more livable and healthy, and telling us to go back to the way we have always been…there is no hope. Are you getting paid from the fast food industry or fake food manufacturers? Just asking

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  8. I agree with both CB and reneejainese, this article (especially its sad title) in its support of the study “by Paul Maclean and colleagues from the University of Denver Colorado, in a paper just published in the American Journal of Physiology.” is effectively discouraging those who have so valiantly lost weight by their efforts of diet and exercise by somehow saying oh oh, sorry, oops you are gonna just gonna go right back to where you were before diet and exercise … as “diet and exercise are not treatment to obesity” Nonsense (somewhere hidden between the lines I can read and thus question … then what is the answer?? is it chemicals from pharma?? or surgery?? hmmm their lies the motivation, I would really like to know who paid money to sponsor the study, was it kind of like the food pyramid by USDA recommending more products of their sponsors i.e. they are funded entirely by meat, poultry and dairy industries) What’s absurd is that they some how research and try to prove the opposite of nature, i.e. that theory needs to be applied in reverse i.e. hey you gained weight from your normal weight so its perfectly possible to go back to your original weight and stay there, here what and how you can do. Now researching, postulating, proving that would be a service to huimanity (not just motivational but medically true too) The reason they don’t say that is they really don’t have that knowledge but … There is hope for all dieters out there … Its already been … done since over 10 years by Dr. Joel Fuhrman, MD and his Nutritarian Diet and his various Eat To Live Books, google him up and follow to T, which helps people not just lose rapid and enormous amount of weight but also keep it off for years together and in most instances reverse serious deseases like artery clogging plaques and diabetes, high blood pressure and that too without drugs whatsoever) His studies fly in the face of this study referenced in this article. I personally am proof myself as testament to my previous sentence i.e. I just began eating Nutritarian way (High Nutrition Density per calorie food more than any other low nutrient foods) on March 20th was 135lbs — my 10 yr ago normal was 130 guess what today after only 2 wks on his diet I don’t crave or feel hungry and have lost 4 lbs so back to131 in 2 wks !!! while doing NO real exercise but lost the weight mostly in the gut / belly fat which is hardest to do even with exercise go figure, I say everyone needs to eat this way for desease free life i.e. not diet for a while and leave and truly thee are no cravings as referenced in this article. My wife started one a week after me and has already committed to change for life. I am not even a patient of Dr. Fuhrman or there is no relation or friendship so no bone to pick for me just picked up his book Eat To Live at a local library fundraiser for guess what .50c and began following his plan. Media is just noise and confusion funded by Oligarchs and Mega Multinationals with wild profit eyes and will sponsor any study to prove any darn twisted theary to keep us enslaved to their products. Always look to nature for real and truthful answers. Myths / Falsehoods like we must eat meat for Protein are hilariously busted in Dr. Fuhrmans book go read it before the gov and lobbyists ban it.

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