Exercise Won’t Make You Fat – And Pigs Still Can’t Fly

by Paul Rogers on August 20, 2009

The poor guy. His name is John Cloud and he recently wrote an article called Why Exercise Won’t Make You Thin for TIME magazine. He, and the article, have taken a real battering from fitness industry stalwarts, including me over at my About.com gig: Exercise Won’t Help You Lose Weight – Wrong!

But you would expect the fitness industry to react to something like Cloud’s article; and I’ve no doubt he knew exactly what he was doing because it did get a disproportionate amount of publicity. His main premise is that exercise makes you hungry and therefore you tend to overeat; or that you reward yourself for those 20 reps you did with a one kilo set of dumbbells by eating a Big Mac, large Coke and large fries.

Exercise Alone Works, But You Have to Commit

Even so, the large scientific reviews of the subject of physical activity and weight loss agree that exercise alone is a difficult road to travel if you want to lose substantial weight. The trouble with large reviews are that they aggregate results. Someone with a strong will and who is determined to lose some weight really doesn’t want to know that most people fail at this — they want to know if it’s possible for them to succeed if they put their mind to it. Yes it is. Absolutely. Tom Venuto wrote a more elaborate rebuttal on his site: Why Time Magazine Owes the Fitness Industry a Big Fat Apology.

Look at it this way. If you burn off 8400 kjoules/week (2000  kcalories) — not an inordinate amount of exercise — that’s roughly around 400,000 kjoules/year (95,000 kcals), allowing for a few weeks off.  A kilo of body fat has around 32,300 kjoules (7700 kcals) (which allows for some water). You can do the numbers, but this works out to a deficit of 12 kilos or 27 pounds a year. Not a lot for some, but a good start for a strategy that relies on exercise alone. Even so, along the way, you need to ensure you don’t ‘pig out’ because you consider you’ve done enough exercise. Add modest calorie restriction, and getting to the fabled weight loss target of a half to one kilo a week is within reach.

The idea that certain people are ‘compensators’ or ‘set-pointers’ who sub-consciously adjust their energy intake and expenditure to maintain any given weight just doesn’t hold up for me. A few people with such a genetic or psychological profile may exist, but I suspect — and there are studies to show this — that people who say they exercise and diet and still can’t lose weight actually eat much more that they admit or show in food records.

Exercise and Moderate Calorie Restriction is Best

In any case, the ideal weight loss strategy is exercise combined with modest calorie restriction. That way, you lose weight and get to keep that muscle and bone that’s so important to overall health as well. The problem with diet-only strategies, especially very-low-calorie diets, is that it’s very easy to lose muscle and bone, and in addition, difficult to maintain nutrient density. Increasing physical activity allows a better diet and helps create that energy deficit that will give you the weight loss.

However, all’s not lost with the Cloud article because it has highlighted a few salient facts about food and physical activity that we should all be aware of. The first is that one hour of walking at fast pace uses only around 1700 kjoules (400 kcalories), while a large, sweet muffin and flat-white coffee and sugar will see you take in about the same amount of energy. Don’t do it unless you’ve done some real work, like an hour of jogging at around 3300 kjoules  (800 kcals). Even then, you need to build that food energy intake into your daily calorie allowance, and not make it an extra.

The other physical activity strategy that works is increasing non-exercise activity called NEAT. Non-exercise activity is the movement you do when you’re not doing organised exercise. The differences in energy use between NEAT maximisers and NEAT minimisers can be up to 1000 kcalories a day, and even just standing for two hours rather than sitting for two hours can use several hundred kcalories extra a day. It is an important strategy in weight loss and should be taken into account.

Summing up, there is nothing new in the TIME article, but it should warn enthusiastic weight watchers that exercise does not give you an lifetime ticket to the smorgasbord. You still have to grind, grimace, deny and denounce. There’s no secret to weight loss and there never was. You do it or you don’t.

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