Health Warning: Exercise Makes You Fat

August 29th, 2009 by Ben Goldacre in bad science, evidence, numerical context, telegraph | 80 Comments »

Ben Goldacre, 29 August 2009, The Guardian

Why would you listen to a government health message, or your GP practise nurse, when the Sunday Telegraph has much more exciting news? “Health warning: exercise makes you fat” is the kind of full-width headline you want to see across a broadsheet page: it’s affirmative, it’s reassuring, and it gives you clear permission to sit on your arse all day. “Re-programming body fat is the key to weight loss, not working out.” Praise be. “Is it possible that all that exercise is doing nothing to make us slimmer?” Please let the answer be yes.

imageThe Telegraph produced three lines of research for this claim. Firstly, more people are spending more money on more exercise than before, but there is also more obesity around in the UK than before: explain that with your science. Then there was some speculative laboratory research about interfering with brown fat in animal models using stem cells and things: interesting to read, but distant from the headline claim, and not much use to you on a Sunday.

To properly examine whether exercise really will make you fat, they described two trials.

The first one, I can tell you right now, is cherry picked. The Cochrane Library is a non-profit collaboration of academics who produce unbiased, systematic reviews of the medical literature, and they have a systematic review of all the 43 trials that have been done on exercise for weight loss. This produces clear evidence that exercise is beneficial, albeit more modestly than you’d hope. “Exercise plus diet” was compared with “diet alone” in 14 trials : both groups lost weight, but 1.1 kg more in the exercise group. High intensity exercise was compared with low intensity in 4 trials, high intensity exercise came out better in all of them, with extra weight loss of 1.5 kg. There are also improvements in blood pressure, cholesterol, blood sugars, sense of well-being, and so on.

The Telegraph quoted one trial from Dr Timothy Church of Louisiana University, which compared three different levels of exercise with a personal trainer in overweight people. There were no significant differences between the weight lost in any of the groups, including the “control” group, who were not given a personal trainer at all. So it is true that exercise did indeed have no benefit, in this one single trial the Telegraph quoted, whilst ignoring the vast, overwhelming majority of published literature examing the same question. Dr Church speculates that the explanation for his finding is that people who exercised more also ate more. Fine.

Then there is the Telegraph’s second trial. “Another study due to be published next month in the journal of Public Health Nutrition by researchers at the University of Leeds draws similar conclusions. Professor John Blundell and his colleagues found that people asked to do supervised exercise to lose weight also increased the amount they ate and reduced their intake of fruit and vegetables.”

I have this trial in front of me. It’s simply not true that participants increased their food intake. Only 15% of all participants gained weight during the study, and these were the only people to increase their food intake, but in any case, the weight gained even by these people was lean tissue, and they lost fat tissue. In fact, what the Telegraph don’t tell you, bafflingly, is that overall, participants doing supervised exercise in this trial lost more weight. Much more weight. In fact, people doing exercise lost 3.2kg more weight, on average, over just 12 weeks.

Prof Blundell says: “the Telegraph article was a complete distortion of the facts of our investigation, which showed that exercise is very effective for weight loss. They completely reversed the outcome of our study.”

Misleading journalism like this is becoming a genuine public health problem. We’ve previously seen the evidence that people change their health behaviour in response to what they read in the media. To add to this, the World Cancer Research Fund recently commissioned a survey from YouGov. This was a proper survey, in a representative sample, from a reputable data collector, where anyone is allowed to see the questions and the results, not a secret PR survey to get free advertising in a newspaper.

Half of all respondents said they thought scientists and doctors were constantly changing their minds about healthy living advice, although in reality, healthy living advice hasn’t changed at all for at least a decade (don’t smoke, do some exercise, eat more fruit and veg). And a quarter of all respondents said that because scientists keep changing their minds, you might as well eat whatever you want, because it won’t make any difference anyway. Have another pastry and put the telly on.


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80 Responses



  1. JonDurham said,

    August 29, 2009 at 7:54 am

    Now I’ve just lost 10kg in about 6 months. My personal, biased, observation is that I did indeed gain a little weight in the first 3-4 weeks, on my exercise-a-lot, eat sensibly diet. I didn’t keep a food intake diary or anything as organised as that, but I did start to notice that I was snacking more. So I stopped that, and cut out some alcohol :-(, and found that – hey presto! – the scales started to go into reverse.

    If the Torygraph is seriously saying that using up more calories that you ingest results in putting on the pounds, I think they should sack their science editor.

  2. Dr* T said,

    August 29, 2009 at 8:22 am

    I look forward to Lord Drayson’s response while still trying to claim science communication is in a healthy state.

    T

  3. David Colquhoun said,

    August 29, 2009 at 8:25 am

    I’m not so sure about the last bit. The broad recommendations haven’t changed for decades and seem to make sense though that aren’t based on very hard evidence (apart from cigarettes).

    But the details change weekly. The World Cancer Research Fund, in particular, wants to micro-manage your diet on the basis of evidence which is often pretty weak. They were in the news again recently, telling people not to eat ham. The evidence that it will harm you is really very slim. The problem is that advice like this is counterproductive. People just laugh at it and the consequence of that is that they also laugh at good advice when they shouldn’t.

    I was amused to see recently that the cafe in the waiting room at the Royal Marsden Hospital was selling ham sandwiches The oncology consultant just laughed when I mentioned it to him. I expect he was right to do so.

  4. Baryonyx said,

    August 29, 2009 at 8:29 am

    This isn’t the first time this myth has been peddled: there’s a great take down of it over at scienceblogs ( scienceblogs.com/drugmonkey/2009/08/the_myth_about_exercise_gimme.php ). Long and short of it: you need to exercise a lot to (60-90 mins, five times a week) to lose weight. If anyone exercises less than this, it should be no surprise that exercise alone doesn’t result in weight loss. Obviously, combined with dieting the required amount is somewhat less.

    Second, even if weight loss didn’t result from exercise, surely the cardiovascular benefits mean that its still worth doing, especially for the obese? Does the Telegraph article mention this?

  5. diggwallah said,

    August 29, 2009 at 8:42 am

    Agree Baronyx. Me thinks the Daily Torygraph confuses fat with fit.

  6. gregpye said,

    August 29, 2009 at 9:04 am

    Well, fat and fit are only one letter different in three, and only 8 letters apart, so that makes them ~90% similar – so, from my one ‘data’ point I think I’ll deduce that they are correlated … I think I could be a journalist yet ;-)

  7. Staphylococcus said,

    August 29, 2009 at 9:48 am

    I’ve never understood all the crap that gets shoveled around with regard to weight gain/loss. On the surface, it’s really quite simple: if your energy intake exceeds expenditure, you will gain weight through storage of excess energy. If you want to lose weight, reduce your energy intake (diet) and/or increase the amount you burn (exercise).

    Of course, below the surface things are a little more complicated but as a general rule, like Dr Goldacre says, don’t smoke, eat more fruit and veg and get more exercise. How hard is that to understand? And yet, thousands of column inches/programming hours are wasted on this rubbish every year.

    0.o

  8. sjgknight said,

    August 29, 2009 at 9:51 am

    Ben you might want to talk to the Guardian who completely edited the end of the article which although it could have been edited, also made a good point. I think the other thing about the telegraph article is that even if the research they posted had been accurate, it didn’t show that exercising had no health benefits nor indeed that exercising (while controlling diet) couldn’t offer weight loss gains. That’s not just bad science in evidence at the telegraph it’s shocking reasoning too.

  9. cim said,

    August 29, 2009 at 10:20 am

    Staphylococcus: the problem with this is that the human metabolism has unsurprisingly evolved to be able to deal with rather irregular supply of food, and can ramp up or down its energy usage quite spectacularly in response to changing requirements and supply. There have been studies where people have been fed 10,000 calories a day – and unsurprisingly put on quite a bit of weight, though even that much food eventually stopped causing weight gain. To return to their normal weight, they just went back to eating their normal amount of food and their accelerated metabolisms just burned it off. There’s a similar response in the other direction, where people who have lost weight due to starvation rapidly regain it (and a bit more, to be on the safe side) when food returns.

    The general rule of not smoking, eating fruit/veg and exercising is definitely going to lead to one being healthier than otherwise. Whether it causes any long-term change in weight is a different matter: probably it won’t.

    It’s worth noting that a 12-week study proves very little about long-term effectiveness regarding weight. There are very few 2-year or 5-year studies, unsurprisingly, but those that there are strongly suggest that there are no (known) exercise or dietary changes that will cause long-term weight loss in more than a few percent of the population. Conversely, almost all increases in exercise or reductions in diet will cause some degree of short-term weight loss over the first part of the study. If you stop the study at that point, it’s like concluding that I can throw a rock into orbit, by only analysing the first second after it leaves my hand.

  10. hat_eater said,

    August 29, 2009 at 10:29 am

    From the point of view of the stockholders it’s not bad journalism, it’s good journalism, ie. this is what the people want to read and consequently are more likely to buy next time. I can’t tell you how much this saddens me, a more and more disillusioned journalist.

  11. Synchronium said,

    August 29, 2009 at 10:32 am

    In that case, I’m going to roll several doobs, sit on my arse and eat crisps all day. :)

  12. Suw said,

    August 29, 2009 at 12:01 pm

    Co-incidentally, I was just reading this article from a couple of years ago that looks at how advice about weightloss has changed over the years. nymag.com/news/sports/38001/

  13. TheLaughingSkeptic said,

    August 29, 2009 at 12:51 pm

    I never cease to be amazed at just how distorted the science gets in some of these articles. Appalling. I only wish more people were aware of this sort of thing. Perhaps then there would be a little less distrust of science and conventional medical advice. Good article

  14. SteveMD said,

    August 29, 2009 at 4:53 pm

    Clearly a silly story and rightly pointed out as such.

    Though it may be possible to make a case that dieting makes you fat, since the “recidivism” rate is well over 90% and dieters very often end up heavier than before they started. O.K., I know it isn’t the dieting, it’s the overeating that makes most people fat, but there is clearly a level of addiction here that is beyond even that of most hard drugs, where the rate of failure (return to drug taking) is often lower than 90%. Until we find an answer, to this extremely strong addiction, isn’t pressurising people to loose weight just causing more problems than it solves, both physically and mentally?

    One problem with exercise is that we overdo it in the beginning, it is hardly a surprise that people don’t keep up something that is either painful or exhausting. Start very gently, just do a little more each day, and I do mean a little. Eventually you will be comfortable doing a useful amount of exercise.

    Another problem, “eat more fruit and veg”? Well certainly include fresh veg in your diet, but we must stop pressurising people to include more and more. The “Five a day” figure is (like the “safe” levels of alcohol limits) a guesstimate, not set in stone as so many reporters and lobbyists seem to think: Professor Sir Charles George, medical director of the British Heart Foundation, was asked why, in view of this study, he advised people to eat 5 portions of fruit and veg a day. He stated that: “There is some argument about how much you need. I think five may be an arbitrary figure.” It may be that the same benefits can be achieved with as little as two portions a week, if so, an easier to stick to message would be “one a day”.

    Too often medical advice not only flies in the face of most peoples experience and motivation to fulfil, which I admit may be misguided, it is also far too preachy in its tone.

    Now we see the early stirrings of the “behaviour police”, who want to force us to do what is best for our health with new laws and taxes. How much mental ill health is caused by pressurising, otherwise healthy people, into lifestyle choices that are initially too difficult or, in the long term, doomed to failure?

  15. SteveMD said,

    August 29, 2009 at 4:55 pm

    Oops! Sorry, in the above post, 3rd para, I left out that a Greek study showed two portions of fruit and veg a week gives as much protection as five a day.

  16. Psythe said,

    August 29, 2009 at 5:17 pm

    Cim, you mentioned that the body can ramp energy usage up and down dependent on calorie intake – which I don’t dispute.

    Do you know how it does it, as a matter of interest? Do we burn more energy in brown fat then just lose the extra heat by peripheral vasodilation (possibly a reason why fat people are often cariacatured as being somewhat red in the face)? This seems somewhat wasteful and I can’t see any evolutionary benefit to it.

    Or do we just become more physically active on a gross scale? One would have thought that this would be fairly easy to account for in such studies.

  17. sburrows said,

    August 29, 2009 at 8:02 pm

    It might be more about fat loss than weight loss. A hard body rather than a lard belly at the same weight might be able to fit fashionable clothes, swimsuits, bikinis or speedos better.

  18. WillWayland said,

    August 30, 2009 at 3:45 am

    Im sorry if this has been mentioned before

    www.time.com/time/health/article/0,8599,1914857-2,00.html seems time magazine beat them to the punch.

  19. Delster said,

    August 30, 2009 at 1:02 pm

    One thing that often get’s overlooked when simply comparing weight gains / loss is what makes up that weight.

    If you exercise more then you build muscle, more so if you do intense exercise. Muscle tissue weighs more per cubic cm (or inch for you colonials) than fat tissue does. So it’s possible to slim down while actually putting on weight.

    During military basic training your likely to eat 6-10k calories per day. I gained 2 stone in 6 weeks and was still skinny while others lost weight on the same intake. Exercise has a huge effect in terms of effect on the body.

    As for the way many people calculate the healthy weight zone…ie BMI….this takes 2 variables into account and makes a sweeping pronouncemnt based on that. To quote from the National heart, lung and blood institues obesity awareness site…..

    “Body mass index (BMI) is measure of body fat based on height and weight that applies to both adult men and women.”

    To give an example….Steven Redgrave…that famous british rower. Calculate his BMI (at his competition weight) and it comes out to 27.7 which the Nat heart lungs etc people list as overweight (you fancy telling him he’s fat?)

    So what it boils down too is simply looking at weight gained or lost is a flawed tool for understanding benefits of exercise…or to put it another way….I think you’ll find it’s more complicated than that.

  20. anitaisabelgomes said,

    August 30, 2009 at 2:06 pm

    It is funny the similarity between bristish media and portuguese ones.
    In the other day the breaking news at the prime time television newspaper with more audiences in Portugal – TVI (I only watch when I am visiting my mum´s cause I cannot watch it in order to keep my mental health! Lol) was “Drinking lots of coffees per day is amazingly good to our health”. I don’t know if you had ever tried portuguese coffee. Believe me, it’s far more strong that the coffee in England… the levels of cafeine are really high! As a degreed nurse and now as a medicine student, after the “reduce the amount of salt in your food” the thing I say most to the patients is “put an effort on not drinking that much coffees” and then it comes the medias and damage everything… just as I can see now it happens in britain :) Ohhhh…

    Post scriptum: Forgive me for all the awfull mistakes I do when writing in english… One of this days I will go to learn english :)

  21. Svetlana Pertsovich said,

    August 30, 2009 at 2:24 pm

    @David Colquhoun

    David,
    Marsden consultant’s opinion is not objective. Marsden hospital is a territory of despair. Marsden’s doctors know that only those patients come to them, who lost all and have nothing else to lose. To smoke or not to smoke, to eat ham or not to eat it – it becomes non-important and inessential in the teeth of real non-curable (or ill-curable) disease. Moreover, those doctors know that there is no radical cure of cancer. Only surgery, which can’t be harmless and traceless. Any so-called “good prognosis” means merely that patient is doomed to live during all residuary part of the life as a being with limited possibilities. The patient is sick person, who was merely pulled through the death, but not was saved from the disease. Marsden is like the Hell. “Lasciate ogni speranza voi ch ‘entrate.” (Dante Alighieri “La Divina Commedia”)
    So if the person didn’t fall into complete despair, better not to come to Marsden.
    Certainly, nobody will say you such thing here. Why? Arrghh.. Because they are “skeptics”… They act according to the rules. And they can’t doubt in medicine even if their friend’s life is concerned. Isn’t it, eh?
    But I am not “skeptic”. I belong to more high category. I am “soviet skeptic”. So I act according to reason and experience. I know that even most great truth can be unfairly impugned. I know that even most honest and great person can be unjustly wronged and brought in the mire and even killed. I know that in the world the mistake is possible. I know that diagnosis can be faulty. And I know that there is the only way to find the mistake. This way is a reason.

    That is why I state – you need no Marsden. You are not its patient. So, all things, which would be said there, don’t concern to you and are not relevant in regard to you. And bear in mind – the price of the mistake is huge. And it is impossible to turn the way back.

  22. muscleman said,

    August 30, 2009 at 4:44 pm

    Exercise definitely has an effect on blood pressure. I am living proof of it. I’m a distance runner and I have to eat salt like it’s going out of fashion lest I faint when I get up from a chair. I doubt that my weight has fallen much if at all recently since the fat I have lost has been replaced by lean muscle tissue and doubtless denser bone mass too (I consume a lot of milk and I don’t even much like the stuff).

    In fact I am now running so much I am close to needing to force myself to eat since I will not be able to rely on my appetite to meet my calorie needs. Unlike all those couch potatoes whose appetites will exceed their calorie needs, which is why they get fat.

    To lose fat simply exercise and be careful about what you eat, hard dieting is not necessary, just don’t have that snack or that second helping. The loss won’t become visible immediately as you lose the most dangerous fat, that around your internal organs first. Belly fat is the last to go, my six pack is nearly exposed. I’d tuck into a doughnut, if I wasn’t gluten intolerant. I would have earned it too, 17.6miles this morning and up at 6am to do so. It was nice then.

  23. brookster said,

    August 30, 2009 at 4:46 pm

    Ben–although I usually agree with most of what you write, I have to take you to task on this one.

    You are correct in your criticisms of the Telegraph article; however, that doesn’t mean that its conclusions are wrong per se.

    The evidence for exercise and weight loss is shaky to say the least. The Cochrane report you published cites an increase of 1-1.5 kg — probably statistically significant but hardly clinically significant. If the evidence for exercise increasing weight loss is so strong, why don’t you quote any of it?

    What you’re saying is that this topic should not be brought up because exercise has a multitude of other benefits. However, at the same time, you ask for a more reasoned public discussion of the complexities of science.

    From the studies I’ve read, diet plus exercise groups when compared to diet-only groups don’t show a big difference. However, the diet plus exercise groups seem to do better at maintaining their weight loss.

    It’s a very complicated topic and I think you’re simplifying it.

  24. David Colquhoun said,

    August 30, 2009 at 5:54 pm

    @WillWayland

    The article you mention on the New York Times is by Gary Taubes, one of the best health journalists I have ever come across (linked to him in bit.ly/12LF5j ). I’m almost through the 601 pages of his book, The Diet Delusion, and plan to post a review of it.

  25. Bogusman said,

    August 30, 2009 at 7:29 pm

    Looking forward to the review. I read the book while on summer holiday and it seemed to be well constructed and the hypotheses presented chime well with my own personal experience of trying to control my weight for over 35 years. It finishes with a passionate call for more and better research on the subject which should be welcome to those who frequent this particular corner of the Interweb.

  26. tim1234 said,

    August 31, 2009 at 2:08 am

    Dr Timothy Church of Louisiana *State* University, that’s the name.

  27. WillWayland said,

    August 31, 2009 at 5:15 am

    @David Colquhoun

    The peice i posted was in Time not the NYtimes.

    Although i do look forwards to the diet delusion review

  28. csrster said,

    August 31, 2009 at 7:27 am

    David Colquhoun: I’ve been trying to find informed online discussion of Taubes’ ideas for a while now, but without much success. Usually someone at scienceblogs, badscience, quackwatch etc. can be relied on to help me work out when someone presenting a controversial view about standard science is a) a nut or b) worth listening to. But strangely Taubes doesn’t seem to have provoked that much interest. Even his wikipedia article is oddly anodyne. So I’m also looking forward to your review.

  29. brookster said,

    August 31, 2009 at 7:29 am

    Gary Taubes did a good piece in The Guardian a couple of years ago on this subject: tinyurl.com/5qclml

  30. Suw said,

    August 31, 2009 at 12:32 pm

    I’ve been reading some articles by Taubes and watching the odd video here and there for a while, but haven’t so far seen a dispassionate discussion of his evidence. What seems to happen in discussions about weight loss is that someone starts saying that the only thing that’s relevant is that you must burn off more calories than you ingest, and continue to assert that in the face of all other discussion points. It seems that there’s an awful lot of dogma around weight, which is really not helpful.

    The other thing is that if one doubts the use of exercise for weight loss, that doesn’t mean that one is doubting it’s importance in overall health and fitness. I’m not a scientist, but it would seem to me to be wrong to conflate the two.

  31. Guy Chapman said,

    August 31, 2009 at 1:24 pm

    I must remember that the 40lb or more I lost in three months of intensive exercise was simply illusory, and the fact that I am now the same weight and waist size as I was in my 20s has nothing whatsoever to do with my daily ride across London and back on a bike. How foolish of me to think otherwise.

  32. muscleman said,

    August 31, 2009 at 2:04 pm

    @Suw

    The glaring gap is the plausible possibility that it is possible to be overweight and fit and healthy, like Sumo wrestlers. This is because such people are thin on the ground because the majority of overweight people in our societies are so because they are sedentary and because the few active overweight people are actually in transition to becoming thinner people.

    I’m with Guy Chapman, I am rapidly approaching the size I was when I was married at 20. I didn’t have anything like 40lb to lose (being a warm person who puts on weight slowly when sedentary) but I did have noticeable fat to lose which has come off nicely giving me excellent muscle definition (fat fills in between them).

    However it is the sheer joy of the sense of enormous well being that is the main benefit of being fit along with the bags of energy being fit gives you. Little is an effort any more apart from kneeling on a Sunday afternoon after my really long run. My legs are just fine today though DOMS are a distant memory.

  33. mattmanning said,

    August 31, 2009 at 3:47 pm

    If you are interested in exercise and fitness then you should read Nautilus Bulletin 1 and 2 by Arthur Jones which can be found at www.arthurjonesexercise.com/Bulletin1/Bulletin1.html

  34. Bogusman said,

    August 31, 2009 at 4:39 pm

    The Guardian article Brookster mentions is the same as the NYT article. Good stuff syndication eh?

    As for the last two points, your experiences are of course valid – for you. One of Taubes’s premises in the book is that fat metabolism is as much determined genetically as height or colour of eyes. On the whole obese people are obese because their body converts more of the energy from food into fat than do the bodies of lean people. If they do then eat more than the lean it is because their (dammit OUR) muscles are then deprived of energy and so the body tries to compensate by taking in more.

    As you have succeeded in losing weight by exercise alone it appears that you are amongst the lucky ones. And good luck to you.

    I have been overweight/obese most of my life but I am reasonably fit and I have a “healthy” diet. My GP tells me I have the blood pressure of a 20 year old. I also know from long experience that no amount of exercise that I can actually fit into my schedule will reduce my weight. When I switched to commuting by bike in London my weight increased slightly.

    Another of Taubes’s theses is that until we start to think of obesity as a physical disorder and stop trying to deal with it as a psychological or even moral problem then we are unlikely to make much progress.

    In that at least I am with him 100%

  35. muscleman said,

    August 31, 2009 at 7:25 pm

    @Bogusman

    When the body is very overweight/obese the muscles become full of intracellular fat. When they are in that state they actively reject insulin’s signal to take up glucose from the blood. This is the basis of insulin resistance that underlies Type2 diabetes.

    Aerobic exercise will, slowly, reverse this by burning the fat stores in the muscles. However if you are unfit your aerobic tolerance will be low and even walking might push you into anaerobic metabolism. So you have to get reasonably fit to even begin to burn fat while you exercise and if you always exercise hard then you will be going anaerobic much of the time and so will not burn fat. You should be able to hold a conversation while exercising to be sure you are in aerobic mode.

    You will gain weight on initiating exercise since as I point out above lean muscle mass is denser than fat. Cycling will build your quads well for eg. Also as I point out above you have to burn the fat in your muscle cells first, then the fat around your body organs before you will begin to burn the visible fat deposits we associate with overweight. However if you can burn the first two you will lower your risk of Type2 diabetes and cardiovascular disease significantly even if you don’t lose the obvious fat deposits.

    So don’t despair and keep up that cycling, it will likely be a long road to getting the weight off, but it can happen.

  36. neveralostcause said,

    August 31, 2009 at 10:27 pm

    But sometimes it *is* a psychological problem, or just a habit of eating too much or foods that are too calorie-dense.

    I eat compulsively sometimes. I can’t stop. Even if I have vomit in my mouth, I might swallow it and eat something else. I remember one time, before I became resigned to it, crying into a pan of brownies–I was crying because I couldn’t stop eating, and while crying, I was eating.

    And I definitely gain weight if I eat high calorie foods and lose it if I favor low calorie foods. Just because it doesn’t seem to work that way for some people doesn’t mean that all people maintain a certain weight regardless of lifestyle changes.

    I frequently actually have trouble maintaining my weight, if I don’t have very convenient access to high calorie foods. But around the holidays, for example, I gain a lot of weight because there’s high-calorie casseroles and cakes and such.

    And, anecdotally, some obese people eat many, many times the number of calories I do per day, and not because they crave that much food–they just drink soda instead of water, or eat an entire pan of cinnamon rolls while watching television, instead of munching on, say, kettle corn, or keeping their hands busy with knitting instead of food. I had a roommate like this last year. Even if she did later require more food than normal people, simply not making mindless, huge calorie consumption a habit would have helped.*

    I highly doubt any one approach works for all or even most obese people. Seeing it as simply a metabolic disorder overlooks those whose obesity is caused or at least severely exacerbated by eating habits or psychological disorders. And those people deserve respect and acknowledgement just as much as the fit obese people do.

    *Okay, thinking about that more, I am far from convinced that your/Taubes’ thesis is correct, but it does seem more convincing. However, why not just restrict calorie consumption to the point where the body is burning the fat for energy? Obviously that’s why fat is stored in the first place, and I think I would’ve heard of people starving while fat if having such a severe dysfunction in energy burning were widespread. Many bone-thin people seem to *prefer* living in a semi-starved state, and I’ve often thought that the real difference is that preference, whether you like the feeling of satiation or of hunger.

    But, really, it doesn’t matter as long as you’re otherwise healthy enough.

  37. iantanner said,

    August 31, 2009 at 10:48 pm

    A science journalist did a “12 scientificlly proven diet tips” abt 3 months ago -sorry no names but, no doubt, someone will remind me. I was tempted to believe what was presented, and what I remember was:-
    1. Protein leaves you feeling fuller for longer (so I’ve taken up egg and baked bean breakfasts in lieue of (carbohydrate) cerial).
    2. Use a small plate. It’s not just that it’s inconvenient eating from a small plate but that you actually feel fuller!
    3. A liquidised lunch of veg/salad in water (soup) leaves you feeling fuller for longer than the green stuff followed by the H2O.

    Ian

  38. JonDurham said,

    September 1, 2009 at 7:04 am

    Here’s an interesting thing – when I’m logged in I can see my first comment on this topic as No 1. When I’m not logged in, it disappears! Is this a WordPress glitch?

  39. jodyaberdein said,

    September 1, 2009 at 7:17 am

    Two points really:

    Firstly how come Blundell’s unpublished trial ends up with the Telegraph? Ben, did you ask him whether he would be repeating this mistake?

    Secondly, with regard to the origins of obesity – I can recommend the interested reader pubmed search Steve O’Rahilly of the Metabolic Research Laboratories Addenbrookes.

    Sloth? Yes Gluttony? Yes. But why doesn’t anyone ever mention heredity?

  40. msjhaffey said,

    September 1, 2009 at 7:54 am

    Q: As usual a riveting read, Ben. Why don’t you report the Telegraph to the Press Complaints Commission?

  41. Bogusman said,

    September 1, 2009 at 11:04 am

    Neveralostcause. I sympathise greatly with you but if you read the Gary Taubes book you might question whether your issue is really psychological. [And you might not and you might conclude that I am an insensitive know-nothing]

    Obviously I am neither qualified nor able to diagnose anything or anyone on the basis of a blog comment, and we should all be aware of the ever-present danger of confusing anecdote with evidence. However I was convinced enough of the case put forward in The Diet Delusion that I would very much like to see more and better research. Unless he is misrepresenting the facts, much of the current dietary advice is based on very thin evidence to say the least.

  42. brookster said,

    September 1, 2009 at 2:56 pm

    I read the Taubes piece a couple of years ago and was originally sceptical, as it wasn’t referenced. However, after digging around in the literature:

    1. The Cochrane review cited in the article is barely an indictment of the exercise/weight loss theory; those figures aren’t really clinically significant and there’s also a margin of error on either side of them. If a pharmaceutical company launched an anti-obesity drug promising 1kg weight loss over and above control, I expect NICE wouldn’t approve it

    2. The biggest meta-analysis I could find was this one (tinyurl.com/mph5h5) in the International Journal of Obesity. It reviewed 493 studies and found little difference between diet-only and diet-plus-exercise cohorts.

  43. irishaxeman said,

    September 1, 2009 at 5:55 pm

    I’m quite amused – do any of these scientists have a reasonable history of taking real exercise? Are any of you immersed in exercise culture?

    The major confounding problem is simply the prior status of the participants to my mind. If you take those with a positive prior sports history you are likely to get big changes IMO, whereas if you take those without such histories you will get more diffuse responses. Also the exercise regimes are usually ones that trainers would recognise as poor conditioners (e.g. treadmill, cycle etc) regardless of their intensity or density or volume (and are these three interacting factors controlled?).

    An example – 30 minutes high density weight training three times a week will shift fat fast, and coupled with some low intensity aerobic work (e.g. cycling in the real world being the best and least injury potential). The schedule needs to be irregular and varied to ensure maximal challenge (think hunter-gatherer). If you want to go Hollywood (where did Christian Bale get those muscles???) you can do low-fat for a while but not really recommended for health. You will look/feel healthy and lose some weight on such a regime – any study use some of these established methods – probably not.

    So I don’t think that the marginal difference from the Cochrane studies (or many others) is a basis for theorising about weight loss and exercise UNLESS there are solid studies using established weight loss protocols from the world of exercise out there.

  44. Health Pain said,

    September 1, 2009 at 7:50 pm

    Important article, very good.

  45. Bogusman said,

    September 1, 2009 at 10:02 pm

    Irishaxeman

    “An example – 30 minutes high density weight training three times a week will shift fat fast, and coupled with some low intensity aerobic work (e.g. cycling in the real world being the best and least injury potential).”

    No it won’t. Not if you’re me anyway. Tried it with a personal trainer a few years back. Felt better and fitter but zero weight loss.

    Everyone is different. It would be nice if those who who won the genetic lottery had some sympathy for those who didn’t. Not like this pleasant chap.

    www.timesonline.co.uk/tol/comment/columnists/giles_coren/article5904268.ece

  46. Bogusman said,

    September 1, 2009 at 10:13 pm

    @Muscleman
    Can you point me to the evidence base for your statements?

  47. genocidefish said,

    September 1, 2009 at 10:23 pm

    This reminds me of supply-side theory.

  48. Alexa said,

    September 2, 2009 at 5:20 am

    Bogusman you seem to be relying on anecdote yourself. Because you have never been able to lose weight even though you’ve tried exercise does not mean that obesity is purely or even primarily physiological. Yes some people like yourself have such unlucky genes that nothing works. But if obesity was primarily blamed on our genes, why would we suddenly see such a rapid increase in overweight and obesity within 20 or 50 years of countries reaching a certain level of wealth and luxury?

    I would be willing to bet that the reason long-term weight loss is so difficult to achieve, is because ingrained habits are so difficult to break. If you have a 9 to 5 desk job that you are forced to drive to, there is only so much exercise you can fit in to your lifestyle. If you grew up thinking it was OK to drink Coke with every meal and dessert after every dinner, it’s incredibly hard to make long-term dietary changes.

    We’re reaching a point where humanity has to make a choice. We either need a fundamental shift in housing, transportation, food advertising/ pricing and lifestyle to move away from sedentary life and into active living/ healthier eating … or we need to bleed more and more money in treating dozens of preventable diseases and accept gastric band surgery as the norm. Of course the third option is to condemn our children to live shorter lives than ourselves.

  49. Bogusman said,

    September 2, 2009 at 8:23 am

    The only way in which I am relying on anecdote is is to use my own experience as the “black swan’in the argument. I did not grow up believing it OK to drink Coke with every meal (hideous thought) or to eat dessert or to avoid exercise or any of the other things you believe are the causes of my obesity. In fact for the last 37 years (since my first serious attempt to lose weight at age 16) I have been borderline obsessed with reducing my calorie intake and increasing my activity. I have found empirically that for me exercise has no bearing on weight whatsoever. I can lose weight temporarily by semi-starvation, and especially by the near total elimination of refined carbohydrates, over an extended period. Having established to my own satisfaction that the causes of my weight problems are not the ones that you probably believe I would very much like to see some credible research on the subject.

    Can you point me to the evidence base for these things that you are willing to bet about? If Gary Taubes’s is not guilty of misrepresenting the science then you will find that it is more or less absent. Most advice is based on the “common sense” argument that an imbalance between energy in and energy used drives fat accumulation. But to borrow a phrase, I think that as scientists we must at least consider the possibility that it’s more complicated than that.

    Taubes’s hypothesis about the rise in obesity in recent years is that it is largely driven by the increased availability and supply of refined carbohydrates, some of it as a result of decades of propaganda for low-fat diets. He argues for the hypothesis very convincingly and in the absence of real evidence to the contrary I would really lke to see it tested by proper research.

  50. brookster said,

    September 2, 2009 at 8:40 am

    The other study I forgot to cite was the recent US study where the researchers investigated whether rises in obesity were down to reduced physical activity, eating more, or a combination of the two.

    Their conclusion was that increased energy intake was by far the biggest factor. There’s an article discussing it here: tinyurl.com/propha

    Unfortunately this discussion is full of anecdotal evidence to support individual posters’ pet theories. I’m far more interested in the science behind weight loss.

  51. gentleben said,

    September 2, 2009 at 11:54 am

    I had a theory that life expectancy was based around a finite number of heartbeats. The faster your heartbeats the quicker you die (like a mouse or a humming bird). Now i have never been fit enough to get to the stage where any significant bradicardia has occured, therefore by exercising all i am doing is using up my precious beats whilst doing something very boring (gym going, not proper fun sport)I used this to explain the significant number of rock and roll stars from the 70’s (when amphetamines were very popular) popping their clogs at an early age e.g Joe Strummer / all of the Ramones).
    I occasionally use this theroy to talk myself out of exercising especilally if it is going to be boring.
    I know my theory is bollocks but looking at this telegraph article i might get onto there science editor with my new ‘amazing discovery’

  52. beergut said,

    September 2, 2009 at 2:04 pm

    @Bogusman (post 45)

    In post 43 Irishaxeman said, “… xxx will shift fat fast”

    You said, “No it won’t. … Tried it … zero weight loss. ”

    I didn’t see Irishaxeman predict weight loss; I saw him predict a reduction in fat. As others have said earlier it is possible to be losing fat but not losing weight (as you are gaining muscle).

  53. muscleman said,

    September 2, 2009 at 5:49 pm

    @Lantanner

    The protein vs carbs for breakfast thing is too simplistic, which carbs? Cornflakes for eg are high GI, honey nut versions even more so. If you eat those for breakfast you will feel hungry again very quickly. Some of the mueslis and even some of the quick and convenient porridges are also not low GI. I eat muesli I make myself that is high in dried fruit and has a lot of seeds and nuts. There is no added sugar and I put no sugar on it. It is thus a low GI, moderate protein (from the nuts and the milk) breakfast that keeps me full well into lunchtime to the extent that if I don’t watch the time and rely on my stomach to tell me to eat it can be past 2pm before I feel the need to eat*, like today.

    *this is a problem for me since I run late afternoon/early evening and eating a late lunch can interfere with that in unpleasant ways. I’m just off for a run now in fact.

  54. Wilbert said,

    September 3, 2009 at 2:34 am

    I’m a postdoc working in metabolic research (obesity, diabetes etc; I did my PhD in Steve O’Rahilly’s department, mentioned above). The obesity problem is too complex to really discuss in a post here, but here are some rambling thoughts.

    – You will only gain body fat if your energy intake exceeds energy expenditure. This is obvious and has been stated above, but also involves a complex interplay of social and genetic factors. But even so…

    – Exercise does NOT make you fat (though it might make you gain weight from muscle growth, as mentioned several times above). This is ridiculous, and a dangerous seed to plant in the minds of lay readers.

    – Exercise has myriad benefits independent of weight loss. Exercise should also facilitate maintained weight loss because it will increase muscle mass and decrease fat mass; muscle is far more metabolically active than adipose tissue, therefore increased muscle mass will lead to increased basal metabolic rate.

    – Obese people have high serum levels of leptin (a hormone released by adipose tissue that signals to the brain to suppress appetite and stimulate basal energy expenditure). However obese people are leptin-resistant: they don’t respond to the elevated levels and so continue to eat (leptin didn’t evolve to make fat people feel full). The downside is that the neural circuits that control appetite may become adapted to abnormally high leptin levels, so that if an obese individual begins losing body fat by dieting, corresponding decreases in leptin result in increased hunger and decreased metabolic rate. Basically, the brain may think you are starving and so tells you that you’re hungry, whilst making the body conserve energy. Not great if you’re trying to lose body fat. This is one reason why losing weight by dieting alone is difficult. Far better to couple dieting with exercise (which will counter the reduced basal energy expenditure with increased physical activity).

    – The incidence of obesity within a given population roughly follows a bell curve because of the variability amongst that population of the genes and social factors that influence obesity susceptibility. Social/environmental changes over the last 30 years have seen this bell curve shift to the right (to higher BMI/body fat%/etc). The downside is that even a slight shift to higher average BMI/body fat% will cause a disproportionate increase in the number of people at the obese/morbidly obese end of the spectrum. The upside to this is that, on a population level, even a modest decrease in average body weight (say, 1.5kg) will have a big impact on decreasing the number of morbidly obese individuals. This is why I disagree with brookster’s comment, above, that a decrease of 1-1.5kg is “hardly clinically significant”. On a population level, such a decrease would be hugely significant.

    Although I work in research (where one general goal is to develop a drug to combat metabolic diseases) I’m more sympathetic to the sociological solutions described above by Alexa (#48, third paragraph). Even so, several studies show that lifestyle interventions aren’t very effective, hence the continued research in pharmacological approaches. I find it depressing that society is being crippled by what should be a readily preventable disease, but addressing the social and environmental causes of the problem is difficult to say the least.

    Apologies for the extended rambling…

  55. irishaxeman said,

    September 3, 2009 at 10:52 am

    One of the major obstacles to weight loss by exercise is the idea, implanted by the media, that you have to put in hours every day in a gym, on a bike or treadmill, carrying a designer waterbottle containing an expensive recovery drink. So people either don’t bother or give up, especially when faced by anorexic gym bunnies.

    The reality is that it takes half an hour a day and can cost relatively little IF someone who hasn’t got a vested interest in selling you a gym membership tells you how. A friend of mine who was the chief instructor for a major fitness group tells me she went mad trying to persuade women you could lose weight doing weight-training, and that low intensity aerobic didn’t work.

    So the problem is not cured but exploited by the leisure business and complicated by health and safety regulations. The equipment you really need for weight loss in a gym is no longer in most gyms – Olympic barbells, squat racks, and knowledgeable instructors.

    As the previous poster says, muscle metabolises faster!

  56. brookster said,

    September 3, 2009 at 12:10 pm

    @wilbert
    “… muscle is far more metabolically active than adipose tissue, therefore increased muscle mass will lead to increased basal metabolic rate.”

    But the calorific differences per day between adipose and muscle tissue are tiny. I’ve seen figures quoted of 5-6 kcal/lb for muscle and 2 kcal/lb for fat.

    What interests me is the question of why diet-only and diet-plus-exercise cohorts lose similar amounts of weight in clinical trials?

  57. Wilbert said,

    September 3, 2009 at 1:19 pm

    @brookster

    but a very small difference in total energy expenditure, over a long period of time, has a significant impact on energy balance and therefore on your amount of body fat.

    I don’t have detailed knowledge of the clinical trials you mention, but I think others above have pointed out that diet-only may reduce body fat, whereas diet-plus-exercise will likely replace some of that fat with muscle and thereby negate weight loss of decreased body fat. What would be interesting would be an analysis of body fat % in these trials. And even if there were no difference (which I would find surprising), the diet-plus-exercise group would likely see improvements over the diet-only group in other more objective measures of metabolic health (serum triglycerides, fasting glucose levels, insulin sensitivity, etc).

    and I agree with irishaxeman. Many people think ‘exercise’ has to be a tedious chore that you pay for at the gym. Even if you don’t enjoy sport, you can still incorporate small lifestyle changes that will make a big difference over the long term (e.g. always using the stairs). Too many programs about weight loss (I’m thinking Trinny and Susannah-type crap) focus on dieting and treat exercise as some kind of hell that is better avoided. This is appalling. One of the many upsides of a more active lifestyle is that you can (within reason) eat what you like, which is far nicer (and healthier) than trying to stay ‘healthy’ by constantly fretting about your diet.

  58. brookster said,

    September 3, 2009 at 2:24 pm

    @Wilbert

    No, I don’t buy that explanation.

    Go back to the big meta analysis I referenced. The diet and diet-and-exercise groups both lost about 11kg on average.

    The diet-plus-exercise group were doing moderate exercise — walking, jogging and suchlike. Now, it’s debatable whether moderate exercise increases your muscle mass *at all* (someone find me a reference), but let’s be very generous and assume this group gained a kilo of muscle and lost 12kg of fat.

    This kilo of muscle weighs 22% more than the kilo of fat, so we’re only talking about 200g here. From the calorie figures I posted above, replacing about 1kg fat with 1kg muscle increases your resting energy expenditure by around 10 calories per day. Which is about a small bite of a single slice of white bread.

    Don’t get me wrong; I’m not advocating not doing any exercise. I’m just sceptical about its usefulness as a way of losing weight.

  59. Wilbert said,

    September 3, 2009 at 3:33 pm

    @brookster

    I haven’t actually looked at the meta analysis, so apologies if that undermines any statements I’m making! A quick look at pubmed finds this reference, showing that moderate exercise does increase lean mass:

    www.ncbi.nlm.nih.gov/pubmed/19188848

    admittedly this is in post-menopausal women, and both loss in body fat (-0.33kg) and gain in lean mass (+0.31kg) are small, but still shows that moderate exercise has an effect.

    Also I’d refute your statement that a kilo of muscle weighs 22% more than a kilo of fat! But I’m with you on the effects that swapping a small amount of fat for a small amount of muscle will have on energy expenditure. The key is where that fat is lost from; losing small amounts of fat from the liver, heart or skeletal muscle will greatly benefit metabolic health, even if net weight loss is small or nothing (or even if you gain weight).

    Perhaps the main issue here is that people seek to lose weight (fat) for the sake of vanity rather than health.

  60. brookster said,

    September 3, 2009 at 4:28 pm

    @wilbert

    “Also I’d refute your statement that a kilo of muscle weighs 22% more than a kilo of fat!”

    I know I shouldn’t use Google Answers as a source, but the author has referenced his figures — the quoted figure is that muscle tissue is approximately 18% denser than fat tissue.

    answers.google.com/answers/threadview?id=576481

  61. Alexa said,

    September 4, 2009 at 2:54 am

    @Bogusman: “Can you point me to the evidence base for these things that you are willing to bet about?”

    I base my hypothesis on sources such as the WHO who look at incidence of overweight and obesity worldwide. When countries develop to the point where work becomes more sedentary and convenience foods become more common, their populations become more obese. Details can be found here.

    www.who.int/dietphysicalactivity/publications/facts/obesity/en/

    As long as someone lives in a society that has created situations that make maintaining a healthy weight so difficult, individual diet and exercise interventions are swimming against the tide.

    I applaud the work of Wilbert and others who are seeking medical solutions to lifestyle diseases. But I do hope governments start waking up to the idea of more societal solutions.

  62. Suw said,

    September 4, 2009 at 8:17 am

    Interesting debate. I notice that so far no one has mentioned the effect of stress on appetite and, therefore, weight. When I was young, stress made me lose my appetite and I maintained a fairly skinny frame. Now it makes me hungry and I maintain a fairly… let’s say squishy frame, despite best efforts. And it’s not the kind of hunger you can easily ignore, either.

    So what’s the link, and how important is it? If stress can in some people increase appetite and preference for sweet foods (as some of the abstracts I’ve just looked at conclude), is that enough to counteract the effects of exercise? Does lowering stress improve weightloss?

    Willpower has to come into it too. Is willpower affected by stress (I’d guess it’s decreased)? If stress does decrease willpower and increases appetite, it would be harder for stressed people to stick to a diet and exercise regime. That would indicate that people looking at reducing their weight should address stress problems too.

  63. EleanorC said,

    September 4, 2009 at 10:53 am

    And today we have:

    1. study finds people with skinny thighs have more heart/cardiovasc problems;

    2. media reports this as “Having large thighs is good for you”;

    3. people everywhere go “Woohoo, pass the doughnuts! Aren’t scientists stupid with their mixed messages?”

  64. Bogusman said,

    September 4, 2009 at 11:01 am

    Alexa, the WHO page is heavy on associations and assumptions but a bit light on actual clinical evidence for cause and effect.

    Just a thought on use of BMI as an indicator which features on the page. BMI uses height squared as its denominator. Since we live in a 3-D universe there should really be a third power in there somewhere. The effect of not doing so is that average BMI will tend to increase with increasing average height in the population regardless of actual changes in bodily composition. Has the WHO corrected for this in assessing the extent of the obesity “epidemic”?

    Just for clarity – I do not doubt that obesity has increased in recent years but I do think that reliance on BMI as the main or only indicator has exaggerated the numbers somewhat.

  65. brookster said,

    September 4, 2009 at 1:35 pm

    @ Bogusman

    I think BMI is still useful for most people. It’s not very useful for people with very high muscle mass (such as sportsmen) or people with very low muscle mass (such as very old people). But those two groups are a small proportion of the total population.

    Its weight categories are also not universally accepted, but you’d need to ask an expert about that.

    I believe most health professionals now also use waist size as a criterion for weight-related risk factors.

  66. irishaxeman said,

    September 4, 2009 at 8:14 pm

    I find it fascinating that the accumulated experience of thousands, possibly millions, of sportspeople can be ignored because trials – albeit well-constructed – are done using protocols that are relatively ineffective. It’s not rocket science.

    I’ll quite happily issue a challenge to the ‘exercise doesn’t shift weight’ lobby. You maintain a monitored replacement calorie intake and do the old professional sprint circuit training – starting with 5 reps each of pressup, squat jump, ab curls and alternate leg shifts (leg shoots in a pressup position) – with only changeover rest. On day 2 you do 6 reps of each and so on daily until you get to 20 when you split to 3 sets of 10, then on to 3 sets of 20, 4 sets of 20 and so on building the volume. You could get to the 100 rep per set state like Alan Wells did prior to his Olympic 100m Gold in 1980. If you get to daily volumes of 10 sets of 20 (remember the monitored calorie intake?) and have not lost a kilo, then I’ll accept your contention. But until that kind of very gentle and gradual, but eventually brutal, progression is incorporated into studies, I stick with forty-plus years of doing weight manipulation and seeing the evidence in others.

  67. Bogusman said,

    September 5, 2009 at 1:08 am

    This sounds like a good component for a trial. You would need a decent sample size and also a control group that didn’t follow the exercise program. You would need to randomly allocate your volunteers to one group or the other and then monitor both groups. Obviously it would not be possible for the trial to be blind because subjects would be well aware whether they were following an exercise program or not but possibly the weighers and measurers could be blind.

    Others in these parts will know more about how to make such a trial statistically valid (I’m afraid I slept though most of my stats lectures 35 years ago).

    It would be really great to see it done though…..

  68. brookster said,

    September 5, 2009 at 9:55 am

    “I find it fascinating that the accumulated experience of thousands, possibly millions, of sportspeople can be ignored because trials – albeit well-constructed – are done using protocols that are relatively ineffective.”

    Erm, isn’t that exactly the logic that proponents of alternative medicine use?

  69. Suw said,

    September 5, 2009 at 10:47 am

    Regarding the athletes, are they fit because they are athletes, or are they athletes because they find it easier to be fit?

  70. lomasj said,

    September 6, 2009 at 7:09 am

    Its clearly not the Science Editor as fault – its a simple mistake on behalf of The Editor. He doesn’t know how to spell ‘fit’. The actual headline must surely have been ‘Exercise Makes You Fit’ – but clearly that would not have been a very interesting article!

  71. dabscience said,

    September 7, 2009 at 9:36 am

    Exercise may give you big thighs, but the good news is:
    “Large thighs protect against heart disease and early death”
    This headline apparently from a BMJ press release that quite rightly attracted criticism from Gary Schwitzer of HealthNewsReview.org.

    The article to which the press release is referring is rather interesting and is accompanied by a well considered editorial that examines among other things the plausibility of such an association:
    www.bmj.com/cgi/content/abstract/339/sep03_2/b3292

    Neither article nor editorial stray anywhere near making the sort of claim alluded to in the press release.

    Clearly such catchy headlines attract the attention of editors in the media, but BMJ are shooting themselves in the foot with this sort double standard.

  72. mikewhit said,

    September 7, 2009 at 5:07 pm

    In any case, not losing weight is not the same as getting fat – doesn’t muscle weigh as much (more than?) fat tissue ?

    Hence if you were ideally replacing fat with muscle, you would put on weight – no-one could say you were thereby “getting fat” – ask the Governator !

  73. evilphil said,

    September 8, 2009 at 9:19 am

    @68 – I don’t think that’s valid. Exercise trials are inherently difficult (compliance with regime and diet particularly problematic). Homeopathy and other CAM are actually easy to test in a double-blind randomised trial, so the trials easily trump the anecdotal evidence / wishful thinking. What Bogusman is pointing to is more like a (very) large number of individual case studies.

    Suw’s criticism is more valid though – an examination of athletes is self selecting.

  74. Bogusman said,

    September 8, 2009 at 10:39 am

    Quite right. I do appreciate that it’s hard and that’s probably why there is not much good quality data about.

    A lot of experience (including my own) is very much tied up with circumstances and environment and a myriad of confounding factors. At best it provides some information about what happens to a specific individual in a specific environment who is subject to a specific set of interventions. This is far from useless but equally it is far from telling a coherent and complete story.

    Clearly there is a relationship between energy intake and fat storage and energy expenditure. At the limiting case if your intake is reduced to zero you will eventually die and it is likely that you will become very thin first. However the idea that from this we can imply some sort of linear or even regular relationship between the variables seems to me to be extremely simplistic.

    As this is one of the most significant public health issues in the developed world it seems to me that we, as a community, should be devising ways to research the problem effectively rather than issuing “government guidelines” that are at best based on guesswork.

    I think that this is the most important take away from the Taubes book and I am very much looking froward to seeing David Colquhoun’s review.

  75. mudpaddle said,

    September 10, 2009 at 12:35 pm

    irishaxeman: Prof Blundell certainly has a history of exercise, he’s a runner and has completed several marathons

  76. samhealy said,

    October 25, 2009 at 4:16 pm

    In fact you don’t need the evidence of specific clinical trials to prove that more exercise — food intake and ambient temperature being constant — reduces weight.

    The human body gets its energy from food.

    An idealised perfect combustion system, running at 100% efficiency, will still lose mass as it burns energy according to the mass-energy equivalence relation. Human muscle tissue is fairly efficient (17-26%, Stephen Steiler) but nowhere near perfection. Exercise requires lots of mechanical energy. More fats and sugars will be burned by an exercising body than a sedentary one.

    Unless more food is eaten, environmental temperature changes or some other efficiency-altering parameter is tweaked, exercise will reduce the weight of a human body as certainly as driving a car will reduce the weight of the fuel in its tank.

    This is a simplified and sort of pedantic argument, but it at least shows that it’s a physical impossibility for an exercising body to lose less weight than a lazy one, if all other energy-related parameters are fixed.

  77. Bogusman said,

    November 3, 2009 at 3:16 pm

    No, I think that you do need to do the trials. I am always suspicious of statements of the “obvious” that are not backed by evidence. Personally I think it quite likely that one of the effects of exercise is to “tweak” some efficiency-altering parameter.

    Suppose for a moment that increased expenditure of mechanical energy caused the body to alter its biochemical processes such that the greater the mechanical energy output the less heat was produced. Obviously our subjective experience is that during exercise we get hot, but it’s entirely feasible that afterwards our temperature drops below the long-term average for long enough to offset the energy used during the exercise. In that way it is possible that exercise would not cause a net increase in chemical energy consumed from food.

    I have no clue whether this is a real phenomenon but I would like to know.

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  80. Jon Wade said,

    October 26, 2011 at 5:12 am

    I missed that headline, that was a good one. There was something equally stupid earlier this year about chocolate, something like “Dark chocolate may be as good for health as exercise” or some nonsense. So many people fell for it that the NHS stepped in and made an announcement: www.nhs.uk/news/2011/09September/Pages/dark-chocolate-and-fitness.aspx

    It is crazy really. I was talking to my mum a while ago, she was trying to remember why she had all these vitamins but could not. “I know I am taking them for something, but I cannot remember what. Maybe I will stop”. She did stop. Still healthy. Probably healthier if those recent reports on vitamins shortening lifespan are at all true.

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