22 January 2010

Exercise, weight-loss and common sense

FitnessDoc, Dr Ross Tucker takes a look at the link between exercise and weight-loss and applies some science and a good deal of common sense to explain how the two work together.

Health24’s FitnessDoc, Dr Ross Tucker takes a look at the link between exercise and weight-loss and applies some science and a good deal of common sense to explain how the two work together.

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, 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 five, 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 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, seven shoes, sex items of jewellery and 180 music items which have some association with weight loss. 

The Cardio Free Diet

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 two 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 recognised 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 "Myths 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 Professor 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 neutralise 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 notmake 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 "kilojoules in vs. kilojoules 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.

Keep an eye out for the rest of Dr Ross Tucker’s series on exercise and weight-loss.

Dr Ross Tucker, is Health24’s FitnessDoc and has a Ph.D. in Exercise Physiology from the University of Cape Town and a Post-Graduate degree in Sports Management from the UCT's Faculty of Commerce. He is currently employed at the University of Cape Town and Sports Science Institute of South Africa, and works as a consultant to various sporting teams, including South African Sevens, Canoeing, Rowing and Triathlon SA. He also blogs on


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