Welcome to the Science of Sport, where we bring you the second, third, and fourth level of analysis you will not find anywhere else.

Be it doping in sport, hot topics like Caster Semenya or Oscar Pistorius, or the dehydration myth, we try to translate the science behind sports and sports performance.

Consider a donation if you like what you see here!

Did you know?
We published The Runner's Body in May 2009. With an average 4.4/5 stars on Amazon.com, it has been receiving positive reviews from runners and non-runners alike.

Available for the Kindle and also in the traditional paper back. It will make a great gift for the runners you know, and helps support our work here on The Science of Sport.

Friday, January 15, 2010

Exercise and weight loss

Exercise, weight loss and common sense sensationalism

I've long felt that one of the biggest privileges of being in the field of exercise science is that what we (sports scientists, that is) study is relevant to just about everyone.  If botanists have flowers and gardens, if astronomers have planets and stars, then sports scientists have...performance, and weight loss.

For almost three years on this site, we've focused almost exclusively on performance aspects - elite athletes, pacing, doping, world records, technology, and have had little emphasis on weight loss.  But the reality is that if ever there was an area of exercise science that was relevant to everyone, it is weight loss.  Whether you are into optimal performance, where carrying 1kg of excess weight is the difference between winning and losing, or whether you are an individual who is told to lose 50 kg (110 lbs) to stay alive, weight loss features on everybody's horizon.

And so we turn our attention to the issue of weight loss and exercise, with our new series, which we hope provides food for thought, and maybe inspiration, regardless of which category you fall into!

The global pandemic and meeting the needs of the market

You've all heard the statistics, I am sure - that obesity is the fastest growing cause of death in America.  That two out of every three people in the USA is overweight or obese, and that this figure is rising, both in the US and the rest of the world.  However, statistics like these are often far removed from what would drive you to take up the weight loss challenge for yourself.  It's all good and well knowing that two in three colleagues may die from a preventable disease caused by obesity (and that you may be one of them), but the real driver for most people to lose weight is closer to home.  So as you read this, your primary concern may be the 5, 10, or 50 lbs that you are looking to lose.  And it's that angle that I wish to take in this series, without dismissing that there is a global problem that needs to be addressed.

Now, when it comes to weight loss, there is no lack of a demand - it is created by your desire to perform, to look better or to be healthier.  This market is enormous, a multi-billion dollar industry, and it borrows from science to pitch a dizzying array of exercise machines, programmes and diet plans at consumers, who, desperate for an answer (in a short space of time) will jump at anything that promises to meet their need.  For example, if you do a search on Amazon.com for "weight loss" and you will discover 83,798 books, which is up from 67,000 books back in May last year.  That means that 17,000 books have been added in under a year.  You will also find two TV games, 7 shoes, 6 items of jewellry and 180 music items which have some association with weight loss. 

One of these books is "The Cardio Free Diet", written by a Chicago-based personal trainer, named Jim Karas.  The book cover promises results in only 2 weeks (this is a classic tactic to hook consumers with), and it proclaims "real results in only 60 minutes a week", "lose the cardio, lose the weight", and "Kiss the treadmill goodbye".  The first line of the book, incidentally, is "Cardio kills.  Your joints, your time, your motivation, and your weight loss goals".

We may get into the details later in the series, but for now, suffice it to say that none of this is true.  Where a tiny element of truth exists, it has been twisted beyond all recognition, or buried beneath sensational advice in the interest of the angle.  This book was a bestseller.  Why?  Because it recognized the need, and then it pitched to consumer an idea that was almost irresistible - that they could lose weight in next to no time, with no cardio at all.  Consumers buy this book because they desperately want it to be true, and are willing to try anything to lose the weight they believe they must.

Unfortunately, this book, and many like it, covering topics like diet, exercise, equipment and medicine, represent "cutting edge knowledge" that has witnessed the greatest explosion in obesity we have ever seen.  Something is wrong with this picture...

Enter Time magazine and the "myth about exercise"

Into this environment, you introduce Time magazine in August, 2009.  A cover story, shown left, promised to reveal the "Myth about exercise", saying that it won't make you lose weight.  Inside, the article produced quotes from professors who said that "In general, for weight loss, exercise is pretty useless".  It told us that vigorous exercise would lead to weight gain, and it explained how years of advice to exercise to help with weight loss was only making us fatter.

It was, not surprisingly, met with a fair degree of condemnation within the exercise community.  I have no doubt, however, that it also attracted a fair amount of attention, and maybe led to the sale of a few Time Magazines that may otherwise not have been sold - remember, the market is saturated with advice and information on a very topical issue like weight loss.  Standing out in the crowd requires a hook, and telling thousands of people who have exercised for years that they are wasting their time is a pretty strong hook.

I bring this up only to make the point that the content of the article, and the angle which is uses to approach the subject must be understood in order to interpret what it said.

The compensation effect - a valuable insight on weight loss and exercise

The truth of the matter is that the article raised some very interesting points.  The central theme is what was called "the compensation effect", the phenomenon where people who exercise without concern for how they manage their diet MAY (not WILL, as the article suggests) actually overshoot their requirement and begin to overeat.  The result may be weight gain, or failure to lose weight.

The article cites one or two studies, in adults and in children, where this has happened - exercise fails to induce weight loss, and one theory is that our subconscious energy intakes simply rise to match expenditure.  The article also includes a few quotes from highly respected scientists.  Take for example the following quote from Prof Timoth Church of the Pennington Biomedical Research Center, who is the author of one of the quoted studies:
"I see this anecdotally amongst, like, my wife's friends," he says. "They're like, 'Ah, I'm running an hour a day, and I'm not losing any weight.'" He asks them, "What are you doing after you run?" It turns out one group of friends was stopping at Starbucks for muffins afterward. Says Church: "I don't think most people would appreciate that, wow, you only burned 200 or 300 calories, which you're going to neutralize with just half that muffin."
There is nothing incorrect with this at all - it's true.  It's common sense.  But common sense doesn't sell very well, and it certainly doesn't stimulate huge debate, which is why the context of these quotes was changed in the article.

But the point I am making is that the article is not nonsensical and completely false.  It actually contains some vital information, which may have been overlooked in the heat of the debate.  The bias of the article is shown in the fact that the author, on numerous occasions, writes that "exercise won't make you thin".  One word would have changed everything, because had he written "exercise might not make you thin", the statement would have been accurate!

Weight maintenance and health - what was left out

The other major criticism of the article is what it left out, rather than what it included.  This is often the case of course - it's what you DON'T say that causes the problems!  And in this particular article, there was no mention at all of numerous studies that have found that exercise is beneficial for weight loss, and crucially, weight maintenance, as well as health of physically active people.  A vast body of research exists to show how exercise improves weight maintenance, working hand in hand with diet and other lifestyle choices to help people get to, and then stay at, an optimal body weight.

Then there is plenty of evidence that shows how physical activity improves health - blood pressure, lung and heart function, cholesterol (lipid) profiles, insulin sensitivity, muscle and bone strength, and so forth.  These studies even challenge the notion that weight loss should be a focal point for people who are exercising.  They suggest that it is better to be fit, even if you are overweight, than it is to be within normal weight and unfit or inactive.  However, this did not feature at all in the article.

Where to next?  Unpacking the theory

So, having pointed out what was missing in the article, and how facts may have been embellished for the sake of sensation, we need to actually unpack the compensation effect.

So that will be the next part of the series - the theory of weight loss.  This includes the infamous "calories in vs calories out" equation, the so-called energy balance, and the source of so much frustration and over-analysis.  But the principle is vital, and that's something to look at, especially to consider how exercise and diet interact to change this energy balance.

Then, we'll look also at the benefits of exercise - the health impact of regular physical activity, which was so completely overlooked by the Time magazine article.   For now, this was an introduction, a quick glance back at the Time piece, which sets the scene for the series to come.



MichaelMc said...

Thanks for tackling this topic. Should be interesting, and probably controvesial. There is so much misinformation (and misinterpretation of information) out there that it clouds the whole issue.

High intensity exrecise vs low intensity, "fat burning" zones, low carb, "fast metabolisms" etc. People seem to become partisan about THE way to lose or manage weight, or just get overwhelmed by the contrary arguments.

Some common sense backed up with solid science would be a welcome breath of fresh air. You've brought that to other topics, so I look forward to your posts.

Chad M said...

I'm looking forward to the real content of this series. I don't think you have to defend the benefit of excercise to your readership as most if not all are already on that train, and dismiss the TIME magazine article as irresponsible journalism. What I'd like to see you tackle is weight loss in relation to high intensity sports training. eg. What sort of diet should an athlete have for weight loss while training for a marathon? What is a realistic weight loss rate that will still enable high intensity quality workouts? What is the carb/protein/fat ratio that will best keep up glycogen stores for high intensity training, but yet prevent muscle loss as much as possible and maintain good health? What other considerations need to be made while losing weight during endurance sports training?

Ross Tucker and Jonathan Dugas said...

Hi Michael and Chad

Thanks for the comments. I hope the series lives up to expectations!

I'll definitely do my best to cover the sub-topics that both of you have suggested. Certainly, things like fat burning zones, heart rate and fat burning, will feature.

However, I have to warn you, the performance aspect of weight loss is NOT my priority in this series. As I explained upfront, this is a topic where the general population, that segment that is not concerned with performance, but rather with weight loss, is more numerous and in my estimation, more significant for this series.

So while I'll certainly cover some topics related to performance, I'm going to focus much more on weight loss basics, benefits of exercise and so forth. And that means commenting on the Time magazine piece - here in SA at the Sports Science Institute, that story produced a huge response, and it required a seminar to deal with the article. People who love sport for health reacted very strongly to that article, so while I realise that many of our readership don't need convincing, I also want to speak to people who are keen exercisers and who may be influential opinion leaders within the field.

Those who have read the site for the last few years will know we are all about performance...usually. This is one exception, and I'm going to speak much more to those who couldn't care less about breaking 3 hour barriers for marathons, or winning club time-trials. Rather, it's the health enthusiast that I'm hoping to speak to.

But hopefully, something for everyone. What I will do is recommend some reading for those who are more concerned with the minutiae, the details and the specifics of performance and diet - Matt Fitzgerald's latest book, Racing Weight, for example, deals with this far more effectively than I will in this series!


Brent Apgar DC said...

Ah the media, after being involved in exercise science and health care for 15 yrs I really have zero confidence in the media to do anything but sell their product at the expense of accurate reporting.
I'm very psyched that y'all are out there filling in the gaps that the popular media leaves out.

I found your comment that it's better to be fit/healthy and overweight to be very interesting. I would agree, from personal experience I often find myself telling very active people/athletes that they need to be eating more, that the body has trouble repairing tissue damage from training/playing if you're trying to loose weight.

I would love it if you did a series on how the endocrine system functions when a person is restricting their calorie intake and how this may impact (negatively or positively) the body as it tries to cope w/ the stress of rigorous physical activity (a high intensity training load).

Looking forward to The Science of Sport in 2010,

Ron Wolf said...

I appreciate your doing this series. Not only because we will all learn something more about diet, but because I'm very happy that you are finally going to look at a topic from the viewpoint of the common person rather than of the elite athlete. Right?

A small, and often repeated vignette - The other day I introduced myself to a newbie runner at the track. Post holiday weight loss was his goal... The look of dismay on his face when I told him that his 3 miles was equivalent to just 3 cookies (KISS principle there) was priceless. I tried to be nice and encouraging.

You may find this next observation to be fascinating. Google Trends shows the relative frequency trend of almost any Google search term over time and geography. I checked the term 'fitness' and, wow(!), the resulting graph shows an amazingly regular and large pulse of interest for about two weeks at the end of every year. Two weeks and then, every year, searches for the term 'fitness' quickly fall off back to the baseline.

Try it yourself --->


A Edgar said...

I have lost almost 50 pounds in the last 5 years and can definitely say that exercise was an integral component of the results I achieved. Now at 52 I am in the best physical condition of my life.

During the process of losing weight I would plateau after losing say 10 lbs. In order to lose the next 10 pounds I had to do two things.

1. Improve my eating habits through smarter food choices and eating smaller portions. This takes time and research, but basically boils down to cooking your own meals and slowly reducing your portion sizes.

2. Take my fitness to the next level. This takes hard work and pain but once your body gets used to it, boy, it feels good. Cycling and running did it for me. I can now cycle and run longer distances and faster at 52 than when I as 21. I am more of a cyclist than a runner and used to hate running, but now that I am in shape I love it.

I attend a gym during our winter months and see committed people that have been attending for over 5 years but are still overweight. I can see that they work hard, but they look the same year after year. I am 100% convinced that they have not changed their eating habits. People have been conditioned to eat too much of the wrong foods. The mainstream food industry has made food addicts of people with fat, salt, sugar, refined carbs and super-sized portions.

Farhad N Kapadia said...

Great Topic. And, IMHO a very difficult one. Superficially exercise has to be good, & I strongly recommend it to all colleagues & patients. However, as I learned through personal experience, the relation of exercise & weight loss is not straightforward. I actually found myself agreeing with the bulk of the Time article, despite the fact that I think media & general is self serving & scientific journalism is woefully superficial.

I lost ~ 15 kg with a strict diet (~1500 cal/day) & some exercise (using the stairs at work; ~ 20 floors a day & weekend tennis). Then, in an attempt at not putting it back on, I started running & joined a gym. & slowly put back 5 kg. I am due to run the Mumbai Marathon tomorrow. I have trained 50-90 km per week for some time, & the weight has crept up by 1-2 kg during this time. Fat content has been stuck at 18-20%.

My current philosophy is; if you want to lose weight, concentrate on diet & if you want to be fit concentrate on exercise. My summarizing points are
1) It’s not about weight loss but about fat loss.
2) To lose weight one needs to be in a calorie deficit.
3) One needs to do some exercise to prevent a drop of BMR secondary to the restricted caloric intake.
4) A simple comparison of calories eaten in a snack vs calories burnt in an exercise session will put things in perspective (the Time article had a good pic of this)
5) As the level of exercise goes up, so does the hunger & it becomes difficult to keep the caloric intake down. For me, the dietary discipline is harder when I exercise more.
On a more scientific note. This whole business of calories in & out is an oversimplification & has too many assumptions along the way. A calorie is ultimately the amount of heat that is needed to increase the temp of 1 ml of water by 1 deg C. There are many assumptions along the way when one tries to project this to a statement like “4 slices of bread contains ~ 200 Cal & a brisk walk of 1 hour will burn ~ 200 cal”. Throw in the fact that some energy is always wasted during every step of it’s capture & utilization & things become even more fuzzy.

Really looking forward to this series.

Ross Tucker and Jonathan Dugas said...

Hi all

Thanks for the comments. great debates coming, I can tell!

To respond very quickly to each:


I'll try to touch on the whole endocrine system issue, but that might be a separate one. Also a very complex one - difficult to study, as I'm sure you can imagine!

To Ron:

Yes, definitely going to focus on the general public and the health aspects, though of course the elite athlete will be mentioned here and there. Most of the principles are the same though, so should be OK to focus on elites.

And thank you for that Google link - I'm going to have a lot of fun with that in the future, I can tell!

To Edgar:

Thanks for sharing your own success story - I think you've figured it out, and without question, diet is crucial to success. And this issue of conditioning, absolutely, there are some amazing studies where scientists have 'magically' replaced food on people's plates as the eat (via a trick plate under the table) and it turns out that people just eat and eat, whatever is presented to them. The appetite is a curious thing! As much as we can say "eat how you feel", it seems that we don't necessarily feel what is optimal and that's conditioning, so it's a vital aspect!

To Farhad

Thank you for the thoughts, you're spot on. And I agree, a lot in the Time piece was sound, but just the focus was sensationalized - as I said in the title of the post, it was common-sense sensationalism!

Your five points are great, especially the final out about oversimplying "In vs out". I'll tackle this in the second part of the series. IN principle, as you've said in your second point, this is how it works, but it's become way to overdone and analyzed, and it's actually a doomed practice, because of the lack of precision in measuring it exactly. It will have to form the basis for discussing the principle, and some examples will be given, but you're spot on, it's "fuzzy"!

Thanks all!


Anonymous said...

As other posters have commented, this is such a good idea guys, well done! Here is my wish list of what I would like to see you cover:

1. A brief, summary history of BMI and other actuarially based weight tables; as an indicator of likely actuarial risk, BMI vs waist circumference vs total body fat measurements (measured using skin-fold, so-called impedance measurements, whole body immersions and other clinical and non-clinical methodologies).

2. A summary of the research for and against the fat but fit argument. Obviously, Steven Blair springs to mind as one of the most eminent and best known proponents of the fat but fit argument. But he has had his critics, still does I understand, and I would be fascinated to read your take on the recently published study led by the University of Uppsala’s Johan Ärnlöv.

3. Straight cardio vs straight strength training vs mixtures, eg circuit training – what are the pros and cons for weight loss: obese and overweight vs normal weight; males vs females; older vs younger adults; adults vs adolescents?

4. Without the use of anabolic steroids, how much muscle mass can the typical adult male and female typically expect to add over the duration of a weight-training program; how is this affected by age; at what point does the typical adult male or female reach a plateau beyond which no further muscle gain is possible without the use of anabolic steroids?

5. How much difference does total muscle mass really make to Basal Metabolic Rate (BMR) and daily energy equilibrium?

6. How important in practise are variations between individuals in BMR to losing weight or maintaining a healthy weight?

7. How does age affect BMR in sedentary adult and adolescent populations?

8. Do endocrine disorders indeed significantly affect BMR, or are they just a new version of the older “big-boned excuse” for being overweight?

9. The importance of net energy losses, ie gross energy consumption less BMR, in losing weight and maintaining weight loss.

10. The importance of large muscle group, energy-inefficient and time-efficient activities, such as fast running, vs energy-efficient and time-inefficient activities, such as easy walking, in maximising net energy losses in a given exercise time slot.

Anonymous said...

Regarding calculating how much we need to eat to lose weight, depending on exercising more, I would like to know how reliable these calory-burning tables are that we find on the Internet.


They seem to present very exaggerated figures.

My other question is that from a lay person's conclusions, I have the impression that if you do a few hours of the same sport in a day, your body doesn't spend the same amout of energy per hour of sport, it seems to decrease, the more you do.

Any scientific basis for this?


Ray said...

Looking forward to it.

I'm always surprised to see "cardio myth" arguments, since personally cycling and running have always been easy ways for me to shed excess weight.

I also never like the over-simplified "calories in/calories out" calculation, as it's too simple to be accurate.