How our beliefs about what controls our weight may actually affect our weight

A couple of weeks ago I was talking to a lady who expressed the wish to lose weight. By her own account she was some 20 kgs heavier than she was many years ago when she was a competitive athlete. She worked full time, had a family and little time for exercise. Her view seemed to be that only if she had more time, she could exercise at a level more akin to her former existence, and would see her return to her original weight too.

It is not often the case that I attempt to disabuse someone of their view, but this was one instance. My experience in practice and also a fair amount of science demonstrates that rarely will someone lose appreciable quantities of weight through increasing their exercise alone. There are many reasons why this might be, but they include:

1. Exercise, unless it’s a lot of exercise, does not usually burn a whole lot of calories.

2. Many people get hungrier and eat more if they become more active.

3. Regular exercise can actually suppress the metabolism (see here for more about this).

4. Exercise can stimulate the secretion of the stress hormone cortisol, which may promote fat deposition (usually around the midriff).

So, imagine this lady were to liberate about an hour a day for exercise, about half of which might be spent actually exercising (after preparation, clothes changing, cool down, and showering). 30 minutes of running might burn, say, 250 calories. But there are about 7,700 calories in a kg of fat. So, theoretically, after exercising for 30 minutes every day for a month she might lose a kg of fat. That’s after 15 hours of exercise and maybe 30 hours of time commitment.

The fat loss here assumes that the additional exercise will not lead to her eating more, a suppression of her metabolism, or cause surges in cortisol that then leads to fat storage. I think exercise is a great thing generally speaking, but it’s difficult to make a strong case for exercise for the purposes of fat loss.

I put this these ideas to her, in the gentlest way possible, and recommended that she might look to her diet as the primary strategy for weight loss. I talked about how when individuals eat right, they very often eat less (often several hundred calories less a day), but without hunger. That, I would say, might be altogether a healthier, more effective, realistic and sustainable way of shedding unwanted fat. And it’s certainly an approach I see work often in practice.

This conversation came back to me this week while reading about a study about the attitudes people have to obesity [1]. This research found that, broadly speaking, people can be divided into one of two categories:

1. those who believe obesity is the result of inactivity

2. those who believe obesity is the result of an unhealthy diet

The interesting thing is that those in the former category tended to be heavier than those in the latter. To me, this is consistent with what I’ve found in practice. As I wrote above, my experience tells me that, by and large, dietary change is more powerful for reducing weight than exercise. Those that believe this are, perhaps, more likely to use diet as their primary weight loss strategy, and are more likely to be successful at weight control as a result. Those who believe that activity is the holy grail for weight loss may, unwittingly, find themselves flogging a dead horse.

Another finding of this recent research was that those who believed weight is primarily determined by activity generally ate more than those who believed diet is more important. I am wondering if this observation is, at least in part, a reflection of a belief some have that they can eat relatively freely as long as they ‘exercise it off’. For the reasons I’ve listed above, I’m not sure this strategy is likely to work out too well. And on top of this, sometimes the issue can be compounded by individuals ‘rewarding’ themselves after exercise with food or drink.

Again, I’m a fan of exercise, I advocate it strongly for those who can and want to take it, and even take it myself practically every day. However, my belief is that the amount of exercise I do is likely to have a negligible effect on my weight. Some may find this belief demotivating. However, for others (including me), it can be liberating and even lead to more consistent exercise habits. Here’s why…

Image I were sedentary and started exercising to lose weight. If I am expecting rapid results but get nowhere very fast, this may cause me to become demoralised and pack it in. However, if I my expectations are better aligned with the likely outcome, I am less likely to end up disappointed or frustrated.

Also, if I were using exercise to lose weight, I might be tempted to see the benefits of exercise mainly through the lens of ‘calories burned’. The truth is, though, that if this were the case there are lots of ‘exercise sessions’ I do which I might conclude were not worth the effort. For example, I regularly engage in brief resistance exercise ‘circuits’ that I think have done wonders for my strength and muscle tone and even built a bit of muscle. However, the calorie burn from these sessions is, I think, negligible. The same goes for my 15-minute swim sessions.

In my case, and perhaps in the case of others, the fact that I do not see exercise as a way to lose weight and burn calories means, in the end, that I am more active (not less).


1. McFerran B, et al. Lay Theories of Obesity Predict Actual Body Mass. Psychological Science 2013; DOI: 10.1177/0956797612473121

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21 Responses to How our beliefs about what controls our weight may actually affect our weight

  1. Nigel Kinbrum 20 June 2013 at 11:43 am #

    Exercise done properly (e.g. a 30 minute walk, a short sprint, body-weight exercises etc) helps with weight loss, by increasing muscular insulin sensitivity and stabilising blood glucose levels.

    I believe that proper diet and proper exercise, is the best prescription for body-fat loss (with minimal muscle loss, or slight muscle gain).

  2. Mark 20 June 2013 at 12:33 pm #

    I’m with the doc on this one. I do a lot of competitive rowing coupled with heavy weight training and people always say to me that if they could devote time to exercise then they could lose weight. My reply is always the same: weight (fat) control is at least 80-90% diet (and here we’re talking about carb restriction not counting calories / low fat nonsense); exercise is just the icing to tone.

  3. Chloe 20 June 2013 at 12:48 pm #

    It’s 80% diet, 20% exercise!

  4. Lori 20 June 2013 at 3:03 pm #

    I’ve found this to be true for myself. Last year, I couldn’t exercise for months due to injuries from an accident. I didn’t gain a pound, but I did lose some strength.

  5. Mike 20 June 2013 at 3:43 pm #

    In regards to weight, my experience has been that as I age the importance of diet has increased, while the importance of exercise has decreased.

  6. Val 20 June 2013 at 5:18 pm #

    If I eat a low-carb diet, I will lose weight, even without exercising.

  7. Jo 20 June 2013 at 9:49 pm #

    My experience with exercise is that when I increase it I don’t lose weight but then I stop for a bit I gain. I’m talking mostly aerobic here which I am now doing less of. I think the body adjusts to the energy loss and it takes a while for it adjust back to what it was – you may be eating more due to the extra exercise as well. I take from this that when starting an exercise routine it has to one that is sustainable for life and health, not just to achieve weight loss.

  8. Diane Smith 21 June 2013 at 6:32 am #

    Some people will use ‘no time, or not able to exercise’ as an excuse as to why they will ‘never’ be able to lose weight.

    I have heard it said that it is obesity that causes people to become inactive not inactivity that causes them to become obese.

    I think it is very important to get this message across to people who are severely overweight. They can lose weight through making dietary changes (cutting carbs and junk foods) and then start exercising when they have lost some weight and probably then feel more able to exercise.

  9. Galina L. 21 June 2013 at 3:27 pm #

    There is a very interesting post on the Kindke blog – Cessation of physical exercise changes metabolism and modifies the adipocyte cellularity of the periepididymal white adipose tissue in rats.

  10. William L. Wilson, M.D. 21 June 2013 at 6:17 pm #

    If exercise has any benefit it is because it improves brain function, not because it burns calories. I have measured my body composition for over 20 years and exercise has no impact on my percent body fat. If you want to stop storing excessive body fat, pay attention to the type of food you are eating.

  11. Rita 22 June 2013 at 3:41 am #

    When I switched my eating habits from semi-vegetarian, with an emphasis on brown rice and legumes, to animal protein, coconut and olive oil, veggies, fruit and nuts (the Paleo diet) I was so busy that I wasn’t exercising at all. Nevertheless, I lost a substantial amount of weight and have kept it off for years.

    Exercise is not required to lose weight, although it sure feels good and has many – MANY – health benefits, including cardiovascular, skeletal, muscular, endocrine, emotional and intellectual improvement and balance.

    People who swear up and down that their weight loss was the result of exercise alone are not telling the whole story. When someone starts an exercise regimen, there is always a concomitant reordering of food priorities. Most people know that processed sugars and starches aren’t good for us, so along with the exercise program the first things to go are the bread, pasta, chips, pretzels, ice cream and candy. Some people also give up meat, erroneously believing that red meat makes us fat (I’m living proof that that isn’t true). But it’s never just the hamburger — it’s the hamburger bun and the french fries they give up with it.

    It’s easier to blame our overweight on lack of exercise due to lack of time (something we can’t always control), than to take responsibility for what we eat. Technically, we don’t need to exercise. But everybody needs to eat, and we do hate to deprive ourselves of foods that give us pleasure, even if they’re keeping us fat.

  12. Jennifer Eloff 22 June 2013 at 4:18 am #

    There is one form of exercise that seems to help a lot of people – not an exercise that I like. It’s running. Most who run consistently are skinnier on average than those who don’t run. Also, it is a way that some people keep their weight at an unnatural low number for their body besides following a strict, low-carb diet.

  13. David Powell 22 June 2013 at 7:04 am #

    I am one of those sad people who collect daily data, I think it must be a genetic trait! In April 2012 I began a daily cycling regime. As the year went on I increased my daily mileage until now it is typically about 7 miles. Occasionally on a weekend I may do as much as 20 miles in a day. Once or twice a week I do a 3.6 mile jog. After each job I weigh myself in the buff on an electronic scale. I have been doing the running for the past 20 years in the same pattern.
    Just to add to the mix I gave up my favourite carbs, potatoes, bread and rice as of Jan 2012.
    Did I lose weight? Yes. By the end of the year I had lost about 25 lbs. But the interesting thing was that when I plotted a graph of daily mileage versus weight across the whole year there appeared to be a direct relationship between the mileage and the weight loss. And interestingly the weight loss does not really start at the beginning of the year when the low carb diet started but only when the mileage increased. I wish I could attach an image of the graph.
    This backs up my previous experience about 12 years ago which when I changed jobs and couldn’t cycle to work any more was the time that I started putting weight on around the middle.

    So I think certainly for some people (me) particular types of exercise (cycling) definitely have an impact on weight loss.

  14. Daisy 22 June 2013 at 7:52 am #

    After struggling to lose weight for around 20 years, I suddenly dropped around 10 kilos last year due to a broken heart. Talk about silver lining!

    I now find it much easier to avoid carbs, but most noticeably I find exercise much easier & my swimming in particular has improved dramatically.

    The worry is, now that my stray husband has returned to the fold, will I start comfort eating again? It seems to me that weight-control is all about the mind…

  15. TinaQ 22 June 2013 at 11:11 am #

    My diet is reasonably healthily and I find that the way for me to lose weight is to eat less carbs but also to be more active.

  16. Robert Park 22 June 2013 at 11:35 am #

    Daisy’s post I find interesting: 14 years ago I lost my first wife to BC and during the months that followed of deep grief I shed about 1.5 stones. This surely would indicate an emotional rather than a mental connection?

  17. Robert Park 22 June 2013 at 11:38 am #

    A postscript to above; during this post-bereavement period my diet could not be blamed as I continued to eat in my normal manner.

  18. W Howard 22 June 2013 at 12:24 pm #

    Thin people run because they are thin, not because running keeps them thin. Running a mile burns 300 calories so that means you would have to run a mile everyday to lose a pound every 2 weeks without eating that extra 300 calories any given day; highly unlikely. Thin people are more inclined to run because they are thin, not because running makes them that way.

  19. Robin Kiashek 24 June 2013 at 3:45 pm #

    In my experience, both professionally and personally, one eats rarely out of real hunger but out of emotional habits.

    Change one’s emotional habits and then one can change one’s eating habits. Exercise will change one’s emotional habits and responses and hence one’s eating habits.

    One reinforces the other and increases the chances of maintaining weight loss medium-long term.

  20. Robert Park 28 June 2013 at 9:35 am #

    I am 82. Until my 70s I had masses of energy that needed to be expended and exercising, in what ever manner, was natural but with moving into advanced old age my energy has decreased when being a sofa spud is delightful. Over those adult years my weight has varied but tended to remain in the region of 13.5 to 14.5 stones whether I exercise or not. Today I am 5’10.5″ tall where as for most of my life I was a tad under 6′. It seems to me that physical activity is simply one of the ways the body rids itself of excess energy and if it fails to do this frustration is the result; it appears to be a question of balance. As the science is done principally by the young this feature of aqeing seems to be overlooked.


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