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Obesity Fact #2: Diets Rarely Work in the Long-Term

Fact #2 about obesity from the New England Journal of Medicine paper states simply that,

“Diets (i.e., reduced energy intake) very effectively reduce weight, but trying to go on a diet or recommending that someone go on a diet generally does not work well in the long-term.”

This statement needs to be read very carefully as it actually comprises of two facts: the first alludes to the fact that reducing energy intake effectively reduces weight (which it no doubt does); the second to the fact that simply being asked to or wanting to go on a diet seldom results in long-term weight loss.

As the authors point out,

“This seemingly obvious distinction is often missed, leading to erroneous conceptions regarding possible treatments for obesity; recognizing this distinction helps our understanding that energy reduction is the ultimate dietary intervention required and approaches such as eating more vegetables or eating breakfast daily are likely to help only if they are accompanied by an overall reduction in energy intake.”

What the authors do not state, but is increasingly obvious (and would certainly count as a “fact” in my books), is that complex hormonal, metabolic and neurochemical changes associated with weight gain result in powerful biological adaptations that serve to defend against weight loss and to promote weight regain.

It are these counter-regulatory alterations, which include persistent changes in neurohormonal activation of appetite as well as marked reductions in resting and activity related thermogenesis, that together orchestrate the biological response to weight loss explaining why the vast majority of individuals, who lose weight with lifestyle interventions alone, fail to keep it off.

Simply stated, the failure of most diets has little to do with lack of motivation or will power – it has everything to do with the fact that the body very effectively “defends” its body weight and will ultimately wear down all but the most compulsively obsessed dieters.

This is not being “negative” about the success of dieting – this is simply acknowledging the reality of our biology.

It is also the rational explanation for the fact that most diets (irrespective of whatever happens to be the current fat: low-fat, low-carb, high-protein, or anything else) fail for most people and why true long-term “success stories” are indeed remarkably rare.

It would certainly help if fact #2 found its way not just into obesity policies but also into the realisation that obesity, once established, requires treatments that have to go well beyond meaningless and ineffective “eat-less-move-more” mantras.

Edmonton, AB


  1. I’m not a doctor nor someone in a science related field, so I cannot speak to the biological changes one goes through when losing weight or maintaining a weight loss.
    I lost 150 lbs in a 1 1/2 years and have maintained that weight loss for almost 8 years.
    I changed my diet to the dash diet because I was diagnosed with type 2 diabetes and I already had hypertension and high cholesterol. I restricted calories to 1600 to 1800 per day and started to exercise. I still exercise 30 minutes 3 to 5 times a week, I don’t count calories on a daily basis. I usually count calories 2 or 3 times a month just to give me an idea of how much I’m eating and it is usually between 2400 to 2600 calories a day so I don’t consider myself a “compulsively obsessed dieter” I eat until I’m full and do not stop myself from eating something because it may take over a certain calorie count. My diabetes is under control my yearly A1c has been either 4.1 or 4.2 for the last 8 years. When I changed my diet my mindset set was on of making a permanent change in what I ate and did not think of it as a temporary diet. From what I’ve read about diets and long term success or failure there seems to be a focus on the biology and not on the psychology of weight loss and maintenance or the behavioral changes one has to make to be successful. If my body did indeed go through the biological changes you are referring to, the behavioral changes I made to lose the weight seems to override any biological changes.

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  2. This is so true. I lost 45# with diet and exercise, regained 12, struggled desperately to relose that 12 – it seemed like every bit of my mental and emotional energy had to be focused on my weight just to keep from regaining every ounce.

    I was fortunate enough to be able to have WLS, which helps a LOT – I lost the 12 and 57 more so far. Even so I’ll always have to be vigilant – there’s a 303# woman inside his 202# woman that will come right back if allowed to.

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  3. “This seemingly obvious distinction is often missed, leading to erroneous conceptions regarding possible treatments for obesity; recognizing this distinction helps our understanding that energy reduction is the ultimate dietary intervention required and approaches such as eating more vegetables or eating breakfast daily are likely to help only if they are accompanied by an overall reduction in energy intake.”

    Until the underlying psychological/chemical/hormonal issues are addressed, no amount of willpower nor determination to “diet” are going to produce any long-term results.

    Yes, caloric intake and exercise are extremely important in achieving the goal of weight loss, but until you discover and accept the reason why you are obese, and how you can alter that mindset for the positive, the long term goals are likely to be sabbotaged.

    And please don’t confuse an altered, positive mindset for willpower. Obesity, in my humble opinion, is primarily influenced by psychological changes, which can hang on from whenever they were introduced (usually childhood/teens) until we can free ourselves from the self/societal-imposed, negative self-image and give ourselves permission to matter.

    Granted, some cases of obesity are, indeed, medically conditioned (Cushing’s Disease, Metabolic Syndrome, Hormonal Imbalance, etc) and need to be diagnosed and treated.

    Yes, it’s important to “eat right” and exercise, but I believe it is paramount that we address and treat the psychological issues, which may have brought us to our present weight before we can commit to any positive, long-term lifestyle changes.

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  4. Culture plays a big role in this.

    Example Group A:
    eat hi-cal food because that’s routine – like having a cheeseburger and fries and fancy coffee for lunch, celebrate every occasion with lots of food – eg you can’t have a birthday without cake, give children lots of treats because they’re children and giving a child cookies shows love, eat whenever you feel like eating, get a box of donuts for the office and another to eat at home watching TV , cook food or buy take-out meals which are high in calories, and eat portion sizes like supersize restaurant meals – and then come back for seconds, …

    Example Group B:
    eat low-cal or moderate-cal food because that’s routine – like having a burger and coffee with milk for lunch, celebrate with music or an evening out or a movie(food might be eaten but it;’s only part of the event), give children occasional treats but certainly not enough to spoil their dinner, eat at mealtime and maybe a snack but not eat constantly all day, plan a meal to be nutritious (including reasonable calories as well as getting protein, vitamins, etc), serve everybody an appropriate portion size with no extra for seconds, …

    Group A is likely to be overweight or obese. If someone told them that they had to change their eating habits to do everything in the second paragraph , Group A would feel like they had been given a “diet”. In fact, they’d probably think it was a strict, restrictive, and “unnatural” way to be forced to eat. It is “calorie restricted” even at weight maintenance levels because it gives fewer calories than their “normal” way of eating. Because to them this is a “diet”, they’d feel deprived, and they’d eventually go off the “diet” and back to the “normal” way of eating.

    Consider Group B, – if if someone read them the second paragraph and said they had to eat like that, they would say, “Sure, no problem, that’s how we eat anyway.” They wouldn’t see their ordinary way of eating as “being on a diet”.

    A particular way of eating can be regarded as either an unrealistic, unsustainable, overly restrictive “diet” , or as just an ordinary way of eating, according to what culture you’re in.

    Not only are there metabolic considerations, there are the cultural beliefs to consider in trying to change eating patterns.
    To some people, any way of eating other than the one that made them overweight in the first place feels unnatural. To have to eat in a way that is ordinary to normal weight people is cruel and unusual punishment to them.

    I grew up in “Group A culture”. I was very overweight. When I left home, in my twenties, I found myself in “Group B” culture. It was quite a revelation to see the difference. I adapted, and gradually lost weight, though I never got skinny. When I go home, my Mom still bombards me with “treats”. Love her anyway. My sibs and cousins think I’m “snooty” because I won’t eat as much BBQ ribs as they do. Oh well.

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  5. Underlying all these comments are two beliefs:

    1) that overweight people eat badly and/or too much.

    Though I am, and have always been, overweight, I come from (as Anonymous puts it) a Group B culture. I believe that my Group B eating habits have ensured that I will not become morbidly obese, but such habits cannot make me into a thin person. Call it heredity or whatever–for me to be thin would require serious and constant deprivation. No, not the deprivation that a Group A person would feel. I’m sure that Group B people can feel deprivation too if they are constantly eating less than their bodies legitimately need.

    2) that overweight people got fat due to emotional issues

    Again, though I am overweight, I have no idea what bingeing feels like. Never done it. I can have one bite of cake or chocolate and walk away. I have a pretty healthy relationship with food, aside from the fact that I can’t eat as much as a “normal” weight person my size. I just gain weight easily.

    In recent years, probably in great part due to the internet and shows like the Biggest Loser or 600 Hundred Pound Woman and the like, those of us who have always been above 25 on the dread BMI scale are all considered to be idiots who stuff themselves silly because they don’t know better or because they bear some terrible emotional scars. When I say this, I am not in any way denigrating the terrible pain of physical and emotional abuse, which can bring on eating disorders. But please, is it too hard to believe that there are lots of heavy people out there who eat “healthy” food, in reasonable portions, engage in regular physical activity and haven’t been victims of abuse?

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  6. Wow, Dr. S, I don’t think your commenters today, with the exception of Kelly-Anne, “heard” what you were saying. They may speak from valid personal experience, but they are anecdotal. Statistically, we who are weight reduced suffer from chronically elevated Ghrelin (Cummings et. al.) and elevated Leptin (Leibel et. al.) not to mention more subtle hormonal and metabolic issues. In three words: it is hard. At least for most of us. I am not insulted by your phrase “compulsively obsessed dieters.” There was a time when I was defensive. I presented myself as defiantly optimistic, possibly inspirational? It was exhausting, actually. And self-deception has a price. I have come to realize that the life I live is out of the mainstream and may be seen as compulsively obsessed. I do, however, abide by the law and pay my taxes. There are worse ways to live.

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  7. “…complex hormonal, metabolic and neurochemical changes associated with weight gain result in powerful biological adaptations that serve to defend against weight loss and to promote weight regain…”

    Dr. Sharma, I believe that the first part of the above statement (regarding “powerful biological adaptation”) has been well researched and documented.

    But the belief that these adaptations “…serve to defend against weight loss and to promote weight regain” is much more wobbly. The metaphors in the phrase “serve to defend against”, for example, suggest that “complex” physiological changes that appear alongside weight gain serve a purpose related to weight homeostasis. This may seem obvious (or factual) but it actually requires reliance on some unproven assumptions.

    What if the weight gain, instead, serves (in some bodies) to create and maintain these “complex, hormonal, metabolic and neurochemical changes” which provide homeostatic brain benefits not yet measured by research?

    While losing 135-145 lbs (depending on the time of year…so far, I always gain some during fall and winter and lose it in Spring and summer), I gradually came to realize that my symptoms of ADD were increasing and at maintenance weight they have intensified in severity by at least 500% (if it helps to provide a quantification for greater clarity.) Also, during weight loss and maintainance, my PTSD symptoms have intensified too, but not as severely as ADD symptoms—and the PTSD symptoms, which are more episodic than chronic, are more difficult to quantify and to separate from their subtle overlap with ADD.

    Both of these physiologically-based disorders or conditions have been part of my life since I was quite young. PTSD symptoms worsened after I experienced another severe trauma in my mid 20s. ADD symptoms have often been debilitating and disabling, more or less disabling according to the quality of self medication or doctor prescribed drugs that I was able to access.

    Here is my main point: when I weighed my highest weight (between 290 and 310 lbs), my ADD symptoms and PTSD symptoms were far less bothersome to me, less noticeable to others, and I required fewer alternative forms of self medication and lower dosages (and fewer kinds) of prescription drugs to treat the symptoms. In addition, I went through menopause, which seems to have provided some mild cushioning for PTSD symptoms but also contributed to worsening ADD symptoms.

    I am still trying to find a physician who will work with me in getting my needs for ADD medications straightened out so that I can become a functioning person again. Doctors seem, in general, insultingly incredulous when I link weight loss with worsened ADD. Whatever those “complex hormonal, metabolic and neurochemical changes” consisted of, I strongly suspect that they served to keep my brain functions (mostly my cognitive, self-regulatory, and executive-function abilities) at a much more advantageous level.

    (Of course, when very fat, I often felt quite distressed about my large size, which social stigma served to make into an economic and social liability.)

    I don’t struggle to maintain my weight. I eat to satiety every day, and have been doing so for about 2 years. (After the initial stages of weight loss, I realized that calorie restriction and/or intense physical exercise were not for me. Made me too dang hungry!) So, eventually, after experimenting a lot, I switched to a mildly ketogenic diet and have no problems with hunger—well, none that an increase in food consumption can’t fix. When I gain weight, I no longer worry that it will remain or increase. My appetite level always drops correspondingly and I return slowly to the lower weight.

    I have attempted to change to a more carb-laden diet, but that doesn’t help my brain to function any better and I just get unbearably hungry on even large amounts. I think I would have to regain most of the weight, and return to “morbid obesity”, before I would experience the “hormonal, metabolic, and neurochemical changes” associated with milder ADD (and PTSD). Not a good trade off!

    Anyone reading, please wish me luck (or pray) that I may find a competent and ethical ADD specialist soon! I’ve become discouraged, and even a kind word might help.

    Thanks for letting me tell my story! Hugs to you Dr. S!

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  8. Hopeful and free – good luck! My story: I find eating carbs MAKES me hungry, go figure. I wonder about your association of lower ADD and lower PTSD with high weight. I hope some scientist looks into what you said because it’s very interesting, that being fat can feel better. What they find out also might shed some light on what’s happening with people with less obvious changes.

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  9. @Annie: Thanks! I too find that eating carbs makes me hungry. I eat carbs, of course, but in small quantities (almost daily: different kinds of berries, full fat yogurt, 90% chocolate, and small amounts of fruit that I grow in my orchard). Being fat didn’t actually “feel better”–overall–but specific ADD symptoms associated with self-regulation and executive function were not as severe (such as being much less able to effectively: organize time, organize things, organize thinking, make decisions, focus and concentrate on conversations and on reading, etc).

    Being that fat was debilitating and oppressive in other ways; for example, I was studying to be an RN (and became licensed), but social stigma against obesity, especially in that field, is often fiercely oppressive. People assume that fatness indicates lack of self care, lack of discipline, lack of knowledge about health, psychological instability (lack of self insight, etc. ) I was constantly reminded, in overt and subtle ways, of my so-called failure to be “normal” and “healthy”—moreover, I was constantly reminded that my fatness (i.e. my abnormal, unhealthy and inferior social status) was a result of my refusal to be “compliant” with basic health practices. Anyway, fat stigma and physical pain associated with fibromyalgia, foot and back pain (which I very seldom experience now) caused a lot of suffering for me. And I still had to battle with ADD symptoms–but nothing to the extreme extent that I do now.

    Modern medicine seems to be rather clueless about the neuro physiology of obesity in relation to the impact of those complex “hormonal, metabolic, and neurochemical changes”. It’s a shame, because the biological knowledge involved (endocrine, neuro, etc) is so very, very basic. Fat cells, after all, play a huge role in all of those functions/systems–such as signalling the brain to increase its access to dopamine, a neurotransmitter which is required in adequate amounts for a brain to carry out specific kinds of executive functioning (neurological) and self regulatory behaviors—yep, the same ones that are impaired in the presence of inadequately-treated ADD.

    But fat bias blinds scientists and health care professionals–prevents them from researching and considering physiological patterns that are not “obviously” related to obesity. So, everyone with a stake in the research game keep looking at the same old stuff, appetite regulation, for example, and looking through the same old lens (weight set point defense hypothesis), and missing the bigger picture entirely. It’s tiresome.

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  10. @DebraSY: respectfully, if I may suggest (not to take away from your well reasoned argument) regarding endocrine challenges post FAT loss—I believe that the brain receives signals (after reduction in FAT cell size) which “indicate” chronically low leptin rather than “elevated” leptin. See Dr. Sharma’s post, for example:

    Best wishes to you, btw, Debra, on your continuing journey into unfamiliar, strange, and little-travelled territory! 😉

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