Exercise vs Weight Loss

In February this year there was quite a bit in the press on the subject of a recently published report on some research which proposes the theory that, beyond a certain modest amount, exercise does not use up extra calories. The reporting continued along the lines of "if you exercise primarily to lose weight, tough luck - because it doesn't work!". More of how this theory works later, but the main point that we wish to take issue with is the general tone of the press commentary which went along the usual lines of "Now we can stick two fingers up at those smug types who feel so good about themselves because they go in the gym and torture themselves, or they run for mile upon mile etc etc. Here's some research that shows us it's not worth doing more than an easy walk for a couple of miles since anything more than that doesn't use up any extra calories, so is pointless. Hah!"

 

Well guess what? This is not a new idea. In fact, even the lead researcher of the project Herman Pontzer, associate professor of anthropology at City University of New York's Hunter College, says that the idea that exercise is not especially effective for reducing one's weight is not new.

 

Here's how this new theory works.

 

The predominant view in the area of exercise in relation to weight loss up to now has been an "Additive" model of energy use in which every additional dose of physical activity used up a corresponding additional amount of energy or calories. This new research, however, supports what the researchers call a "Constrained Total Energy Expenditure" model, whereby the body compensates for high levels of physical activity by reducing its energy use in other areas. Daily energy use for high levels of physical activity, such as exercise, is compensated for by reductions in the body's energy use for other muscular activity - for instance one might sit down rather than stand for some of the time - or some of the body's non-muscular, metabolic activity might be altered. And this is how total daily energy use is kept within a fairly narrow 'bandwidth'.

 

Reading the published research rather than news articles about it, one thought occurred to us so we wrote to the report's lead author, Herman Pontzer, and he was kind enough to reply with an answer to our question, and also sent us another article he had written which related to it. The question we put to him was how it is that elite athletes, who apparently consume upwards of 4,000 calories per day do not balloon in size if people's bodies adapt their energy use in the way he suggests. His answer was that it might be that "elite athletes, in pushing themselves beyond the normal range of human variation, are able to go beyond the body's ability to modify itself and thereby limit calorie use". He also suggested that "a combination of very high physical activity and high food energy intake during adolescence might lead these athletes to develop a metabolism that is very high, and different from most other people". In other words there are always exceptions to any rule, so these individuals "present an interesting challenge" to the theory of Constrained Total Energy Expenditure. His other thought was that the large calorie intake might be connected to muscle building periods of training.

 

Another question has come to mind since then. Firstly, if there is this upper limit on daily energy expenditure, why is it that people who regularly engage in sports and/or exercise generally appear not to be part of the obesity epidemic currently sweeping the developed world. Is it that the energy use of people who don't engage in sports or exercise is generally below the level where additional physical activity uses no extra calories? After all, we're talking about an amount of energy that should be used EVERY DAY, so even if it is only the equivalent of a two mile walk on top of regular activity, if you don't use it, it gets stored as body fat - every day. Another piece of recent research, from Dr Ellen Flint, at the London School of Hygiene and Tropical Medicine says that middle-aged people (40-y-o to 69-y-o) who either cycle to work or use public transport are respectively 5kg or 3 kg lighter than those who commute by car. So perhaps that much daily physical activity is needed to take you to the point where your physical activity has balanced your energy intake.

 

It's important to point out that Professor Pontzer's theory still proposes exercise benefits since many of the effects of the body's compensatory reduction in energy use are in fact themselves beneficial. For instance, a reduction in muscular activity following exercise contributes to post-exercise muscular recovery. And the "non-muscular ways of limiting energy expenditure" could produce beneficial effects by "reducing energy expenditure on inflammation and detrimental immune system activity" according to the researchers.

 

As Professor Pontzer stressed to us, his theory of constrained energy use did not imply that one should not exercise or that the effects of exercise diminish. He was absolutely categorical in his assertion that the benefits of exercise go well beyond its effect on the body's energy expenditure and include "reduced frailty as we age, increased mental acuity, better blood profiles (cholesterol, glucose...), and the list goes on". He continued "We take pains in the article and in the reporting (to the extent that we could direct the reporters) that our study doesn't change the message that exercise is important, and the more the better."

 

All of the benefits that derive from exercise and that Professor Pontzer pointed out are of interest to Silver Grey athletes, and to Silver Greys in general, and they all support the theory that you should make every effort to maintain your strength and fitness in order to retain better functionality, both physically and mentally, throughout the whole of life. If you have ever spent any amount of time unable to exercise for one reason or another the negative effects of that stack up pretty swiftly, and even though you will rebuild your conditioning when you do go back to exercise - and the longer you have been in the habit of exercising regularly the quicker that will happen - it's certainly easier to maintain form and fitness than to regain it.

 

What we really don't need are people putting forward reasons to cut back on exercise, particularly if they are based on a misunderstanding of what's being proposed. So 'journo's', when you set out to write these discouraging articles about exercise, make sure you get your facts right.