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Is Exercise More About “Calories In” Than “Calories Out”?


Most people believe that it is somehow possible to create a sustainable caloric deficit by burning calories through exercise.

This is why treadmills and exercise bikes display calories and many folks obsess about burning those “extra calories” (often only to eat or drink them right back).

Although exercise is certainly not the panacea for weight loss, there is no doubt that a substantial number of folks may experience very significant weight loss after taking up a regular exercise program.

I, however, have long suspected that the substantial weight benefits that these people experience has very little to do with the amount of calories burnt or, in other words, the [calories out] part of the equation.

Rather, I tend to favour the hypothesis that the weight-loss effects of exercise have more to do with the metabolic changes that result from the exercise (e.g. changes in insulin resistance, cortisol, sympathetic activity, etc.) and, perhaps even more importantly, the impact that exercise can have on ingestive behaviour.

Thus, I would not be surprised if the impact of exercise on mood and stress levels as well as the effects of exercise on self-esteem, improved sleep, and general well-being is in the end far more important for any weight loss associated with exercising than the actual amount of calories burnt.

Thus, I would predict that people in whom overeating is driven by stress, depression, poor self-esteem, or unrestorative sleep, will lose weight when they take up exercising – not because they are burning calories, but because they are eating less.

As a corollary, In people who are not overeating for any of the above reasons, exercise is far less likely to lead to weight loss – because it does not help them reduce their calorie intake.

Of course, if this hypothesis is true, it would easily explain why the same amount of exercise leads to weight loss in some people but not in others and why the amount of weight that some people lose with exercise simply cannot be explained by the amount of calories burnt.

In a paper just published in the Journal of Obesity, Jean-Phillipe Chaput and colleagues discuss exactly how physical activity can play a role in body weight regulation without actually affecting calories out.

The paper goes to great lengths to describe the many metabolic adaptations that occur in response to regular exercise and highlight how these adaptations rather than the actual number of calories “burnt” may explain many of the weight and health benefits of exercise.

As the authors also note:

“Regular exercise produces psychological improvements that may help buffering the harmful effects of stress. It has beneficial antidepressant and anxiolytic effect and, as shown in a recent meta-analysis, depression increases the risk to develop obesity. Exercise training also improves sleep patterns. Considering that bad sleeping habits is itself a stressor that has been associated with increased risk of obesity, physical activity can have a stress-buffer effect. There is also some evidence that exercise influences health-related behaviors, such as nutrition, and might help coping with life’s stress, particularly among high-risk individuals. Then, when practiced on a regular basis, physical activity could help breaking the stress-feeding habits.”

If the overall beneficial impact of exercise on body weight (in some people) has more to do with the metabolic changes, the stress relief, better sleep and other adaptations that affect food intake, then really the impact of exercise should not be measured (or predicted) by calories burnt.

In fact, the actual calories burnt may be completely irrelevant as shown in studies where stress-relief or mood management was found to significantly lower body weight. Thus, some people may well derive the very same weight-loss “benefits” of exercise by simply engaging in 30 minutes of quiet meditation or a daily leisurely walk in a restorative environment.

Focusing on “calories burnt” or even equating “calories burnt” with the potential weight benefits of exercise is misleading and frustrating.

As Chaput and colleagues nicely illustrate – the health benefits (whether weight related or not) of regular physical activity may have little to do with [calories out].

I wonder if my readers have noted how exercise affects their eating behaviour – I am guessing that while some folks actually end up “working up an appetite” (possibly resulting in weight gain) others may well have noticed that the stress relief and well-being that results from regular physical activity actually helps them eat less.

This would certainly support the idea that the weight-management benefits of exercise have substantially more to do with reducing calories in than increasing calories out.

AMS
Las Vegas, NV

Chaput JP, Klingenberg L, Rosenkilde M, Gilbert JA, Tremblay A, & Sjödin A (2011). Physical activity plays an important role in body weight regulation. Journal of obesity (Online), 2011 PMID: 20847894

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22 Comments

  1. Dr. Chaput’s paper also states that exercise can have a greater effect on waist circumference than BMI (while reducing fat mass, exercise can increase muscle mass, thereby cancelling weight loss per se). Interestingly, Jean-Pierre Després’ research has shown that the association between waist circumference and health risks is far greater than the association between BMI and health risks.

    In my experience, I have been very successful – I should say too much! – in losing weight through exercise. It takes several days to replenish the calories burnt from a cycling ultramarathon!

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  2. As someone who isn’t massively overweight (never in the “obese” BMI range), I started a quest to live healthier and lose a few pounds a while ago. Apart from eating better (I don’t even have to eat *less* when it’s less processed crap), I decided to take up running in a moment of insanity, an activity I never enjoyed. With the help of a training plan for complete beginners, I found out that my dislike had mainly come about because I’d always tried too much too soon, and it was actually rather fun.

    The thing is, after the first week of “running” (at an extremely slow pace), I already felt a great deal better about myself. I felt fitter and slimmer (none of which I actually was), and infinitely more motivated and energetic. Almost no cravings for crap food, the desire to get fit and eat well superseded the desire to see the numbers on the scale fall (well, apart from the “when I’m lighter, I’ll be able to run more easily”-thing).

    It mostly stopped being about what I looked like and became about what I felt like. Not entirely, of course – I still love seeing my mirror image change – but exercise certainly took care of the temptations to crash diet (it’s not fun when you’re not fuelled) and helped immensely to curb the cravings.

    It’s far too early for a success story – I’ve only been at it for a few months – but so far, it seems to work for me.

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  3. I’ve often said it: my exercise interferes more with my pizza eating than my pizza eating interferes with my exercise. Seems like there are just so many difficult-to-quantify positive effects from the exercise. Makes evolutionary sense. The device (the body) was meant to be almost constantly in use, and its maintenance is predicated on that, like a self-cleaning oven, or those knife holders that automatically sharpen the blade.

    Thanks for the great blog.

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  4. Well since you asked I’ll share my anecdote. Exercising makes me extremely hungry in the short-term, especially if I have been restricting calories too. But when I don’t worry about weight loss, exercise does seem to have the effect of stabilizing my hunger long-term. So for example, I’ll exercise every Tuesday and Thursday night, and then I’ll be starving immediately after and a big dinner. But then throughout the rest of the week, I don’t have as many cravings. I’ll still be hungry around meal and snack times, but I can be satisfied on less food and I don’t get very many cravings off of my normal food schedule. It doesn’t make me lose weight but it seems to prevent me from continuously gaining weight. I have to note that I have several medical conditions that effect my weight, so it’s really hard to link any weight changes to exercise itself.

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  5. I am so happy to see people starting to thing about the very, very complex issues surrounding body weight, health and well-being move away from traditional assumptions. It seems to me that turning the traditional assumption about exercising and “calories out” on it’s head is spot on. At one time, I was morbidly obese (as a consequence, I believe, of a medication I was taking) and I was completely miserable and barely able to move, other than my very physically demanding job (critical care nursing). When I changed meds, the weight just fell off (100 lbs) and only as I have become lighter (and moving has become easier and less humiliating) have I begun to enjoy regular daily exercise. I now do yoga occasionally and take a brisk walk every day for an hour and my sense of well being has improved dramatically.

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  6. It is funny to me, exercise is the one therapy that gets a bad rap because people have trouble sustaining it. How often to paients go off their medications because they think they are “fixed” only to be put back on them again later, examples could include cholesterol, blood pressure, depression, anxiety, and psychotic medications. Yet in all of these cases, the therapy is not considered less effective because when a patient is participating in the therapy the desired effect is achieved. But with exercise, it is somehow considered less effective because when people stop exercising the effect is lost….imgine that.

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  7. I agree with this post completely, but believe there is need for elaboration in one area: for a small niche of people who are highly dedicated, exercise does make a significant contribution to weight loss / maintenance.

    I average 10 hours of intense running, cycling and weightlifting each week because these are activities that I greatly enjoy and even though I work full time and have a family, through effective time management I’ve created a schedule that allows me to do this. This exercise burns roughly 6,000 kcal a week – the equivalent to nearly two-pounds of fat a week – compared to sitting on the couch. Yes, I know that the weight loss I’ve experienced and improvements in metabolic efficiency have lowered my RMR, but if I were to stop exercising and maintain my current diet I would rapidly begin to gain bodyfat.

    Essentially, because I exercise so much I gain some dietary leeway. I can still be slim and drink beer and cheat on my diet. I realize that the level of exercise is not for everyone, but I do believe it is something worthwhile for people to aspire to. The trick is not to view exercise as a means to an end or a punishment to be endured, but as a fun and exciting lifestyle to be fully embraced.

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  8. Thank you for this fascinating, thought-provoking post.

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  9. Exercising regularly makes me slightly lighter (a BMI of 32 instead of 35), but I’m not aware of eating less when I’m more active. In fact, I feel hungrier. Maybe being active changes my body composition a bit and makes my metabolism less efficient (so I burn more calories all the time)? Anyway, weight loss is not a big deal to me. I like to stay active because it makes me feel strong and capable and allows me to enjoy active hobbies, and because it improves my mood.

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  10. Great Post like always!! This certainly changes the way I used to look into exercising for more calories to be burnt (of course in addition to CV benefit) …. THNAK YOU :-)

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  11. As the lead author of this paper, I personally thank Dr Arya Sharma for this interesting blog that gives me other research ideas. I wholeheartedly agree with Dr Sharma about the fact that obesity is a complex condition and we need to address the root causes of the problem. Conditions like impaired sleep and mental stress have been reported to increase food intake (most of the time in the absence of hunger). Because it is extremely difficult to avoid the obesogenic pressures in our daily life, physical activity has the potential to buffer some of them. After all, it is still important to have a sound mind in a sound body.

    P.S. Don’t read this blog too often, it will make you hungry!

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  12. interesting post. I do exercise a lot, daily swim for 1hr, 3 work-outs for 1hr ea and Tai Chi 2x/week for 1hr ea and during summer 4 – 5 x/week golf (driving range/course). It does not make me hungrier nor do I really look at the calories burnt but as other readers said it gives you some leeway in your diet where you can have maybe an extra piece of chocolate. Exercise is so much more then “just” physical activity … it makes me feel proud of doing it, makes me feel good about myself, I feel healthier & slimmer due to muscles I can feel & see and it gives me always a mood & energy boost. Another thing I noticed is that since I exercise daily I don’t want to ruin my healthy behaviour wiht unhealthy foods … it would make me feel bad and I don’t like to be in that mood state. I rather have a healthy food and feel good about myself. I know weight loss/maintenance/management is more a “mind game” then anything else !!!

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  13. I find that running helps “curb” my cravings or appetite. If I have a particularly stressful day and start thinking about eating some foods that may not be the healthiest, running helps to “reset” my brain. The cravings lessen, my mood improves, and I want to eat something healthy after a run. Running, for me, seems to turn the less healthy desires off and helps to stimulate healthier habits. AFter a long run, I want to eat healthy food, not refuel with junk. I also run after work and before dinner (usually a challenging snacking time– before dinner) so this helps manage extra calories before dinner since I’m running instead of eating.

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  14. I just didn’t like the number 13 on your post and had to change it to 14 …One superstitious reader of yours :)

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  15. Exercise is complicated. It may not be necessary for weight loss for some people. However, once people are trying to maintain a radically lower body weight than their body’s highest established weight, then substituting “30 minutes of quiet meditation or a daily leisurely walk in a restorative environment” will NOT do the trick. (It makes me laugh to think about it.)

    The NWCR says that most of us are putting in an hour or more per day of fairly rigorous exercise. I used to be a runner, till my joints and left foot made that untennable. Now I do aerobics on a padded carpet with a weighted vest and other weights (and I test myself with a monthly two-mile run, just to make sure I’m training at my former level).

    It is all well and lovely to say that you have to find exercise that you love (or you won’t continue with it). And this advice is great for people who practice Health At Every Size (HAES) and are content with that. However, this advice for weight-loss maintenance is impractical. Often the exercise you love stops loving you back, and alternatives are much harder to find than the know-it-alls like to think. (Swimming for example, for me, requires more than twice the time-commitment of running to prevent a weight slide). My advice, if you are intent on weight-loss maintenance, is to find rigorous exercise that you can do, then just assume it into your routine and add the joy into your life in other ways. I’m also in favor of multi-tasking. Efficiency is oddly satisfying. For example, during my cool down, when I’m still wearing the weighted vest but slowing my movements (preparing to stretch) I brush my teeth and I select the clothes I’m going to wear for the day and lay them out on the bed.

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  16. This is a great post. All true, however, I disagree with the conclusions about caloric expendature during exercise. I have analyzed over 4000 people to develop exercise programs for their unique body. There are many factors involved which is why calories displayed on a treadmill are very ineffective as a method of calculating a deficit to affectuate weight loss. First of all weight and BMI are totallt dinasoric. I use indirect caloric oxymeter testing, bioelectrical impedence, orthopedic evaluations, moderate CV testing and weight management behavior assessments before recommeding the type, duration and progression of an exercise program. I have never seen two people who were the same, but the results are always exceptional. I do not assume that one will be like the other, and unfortunatley, this is the basis of all clinical analysis.

    How can we possibly look at the complexity of storing fat and not expect its use to be equally complexe? I believe exercise is the fundamental factor that contributes to metabolic function, both in storage and use of body fat.

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  17. To contribute another anecdotal experience –
    I started exercising regularly just over a year ago, and have been able to keep it up for the first time in my life, because of coming to the realization that I feel better – emotionally, psychologically – when I exercise. Before that it was always about “I should exercise so I won’t be so fat”. That never lasted more than a week or two at the most.
    I lost quite a bit of weight at first (I think 20 pounds or so in the first 6 months), but in the next 8 months I’ve only lost about 4-5 pounds. The great thing, though, is that being in shape makes me feel better about myself anyway. And the mood elevation makes it easier to keep the weight off. I have always been a big emotional eater, and it’s only since I starting exercising that I’ve been able to choose other ways to deal with stress.
    In my experience, I notice a marked difference when I don’t exercise for a few days. Usually I feel fine the first day off, but the second and then especially the third day, I start to feel a bit depressed, I find myself craving sweets and snacks like chips, feeling bad about my body, etc. I get kind of desperate to exercise again because I know it will only take 1-2 sessions before I feel better. And it’s not like I’m a marathon runner or anything – I usually just do 20-30 minutes of step aerobics, or weights/jump rope, and maybe 10 minutes on my new rowing machine.

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  18. My anecdote: When I exercise regularly, I am happy, I make choices that support and maintain my healthy weight (rather than over eating), I cope with the unexpected more easily. My appetite doesn’t seem to have the spikes – even after exercise. All in all, life is better when I’m moving my body daily. So I do subscribe to the theory that the importance of exercise (for me ) is less about actual calories burned. And more about well being and stress reduction.

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  19. @DR “It is funny to me, exercise is the one therapy that gets a bad rap because people have trouble sustaining it.”

    I think we really have to look at how we try to motivate people to exercise. Telling people it’s to lose weight can be disheartening when the weight comes off. If my goal of exercise is to lose weight & it doesn’t work, there goes the motivation. If the goal is to find an activity I love and enjoy it because it feels good and I feel better, that’s a whole different story. I find exercise equipment to be particularly disheartening, but I’ve been using a bike trainer this year — but only because I want to ride longer & when the weather is the pits, it’s the only option. I wouldn’t do it if someone told me I was supposed to do it because of my body size. I’m motivated by what I love, not by the calorie count on a screen. (And actually, mine’s a mag trainer at home, so there are no calories burned counts.)

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  20. The only caveat I would add to this that I don’t think has been mentioned by another commenter is the phenomenon of “I just exercised, so I can eat this.” It’s not at all uncommon to trick yourself into thinking that you can indulge (or overindulge) in certain foods you wouldn’t normally think healthy, just because you had a good workout that day.

    On the whole, however, I agree with your hypothesis. In my own experience, I also find that the farther I progress with a given exercise regimen, the more inspired I am to feed my body with clean, nutrient-dense foods in order to maximize the benefits I’m getting from that exercise regimen. It starts a positive feedback loop which tends to keep improving the diet and the exercise over and over again.

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  21. Hi, Dr. Sharma.

    Back in 1997 in March I walked literally 20 miles in a single day ( I know this bcause the road had the mileage) Due to circumstances then I had no other choice. I walked up to 4 hours sometimes, separated by a small break of about 30 minutes. 2.5 hours up , 2.5 hours back.

    I was never obese, but I had the physique of someone who put all his efforts into lifting weights with no cardio all. I was about 223 pounds at 6’2″, but I carried significant muscle, I just had a bit of saddle baggage to lose. So, anyway, I walked and walked 12 to 20 miles a day 2 or 3 times a week, with no journey being any less than 12 miles and as many as 20 . I did this until June or July 1997. I went from 223 pounds on March 16 1997 to 186 pounds on July 8 1997.

    So who knows the mechanism that it worked, but it worked. However, I agree the typical exercise is not effective. It is not nearly enough. But what I did in 1997 is not sutainable or realistic for obese patients. I was never obese so I had an advantage.

    But unfortunatley for a brief time in 1998 I developed “manorexia” and dipped down to 160 pounds. I was semi starving myself eating a mango and a a handful of peanut M&M’s a day, and if I was lucky 3 chicken McNuggets. That was bad. I am glad I recovered.

    But I no longer can afford the time to do all of that exercise, and it was a bit extreme LOL !

    It is a joke in my family ” Want to lose weight”? Eat a 100 Grand candy bar and walk 20 miles” LOL ! True story.

    I will say one thing, those walks cleared the mind PHENOMENALLY and very calming.

    Take care,

    Raz

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  22. I couldn’t agree more.

    I often wondered while in school and from my own personal observations if weight control and healthy body weights was more than just burning excess calories. For instance, I know from my own experience that a regular exercise routine seems to create regular meal patterns in my day; and there is certainly evidence out there that indicate people who have regular meal patterns tend to have healthier body weights.

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