Tuesday, August 11, 2009

The role of exercise in weight loss

I've recently lost a bit of weight by using a controlled diet. By writing down everything I eat (using the Weight Watcher's point system) I managed to lose around 18 kg in around 30 weeks, getting me down from 105 kg to a considerably healthier 87, where I've stayed now for a while. I can now run without breaking my knees, and my current personal record over 10km is under 54 minutes. Using a pulse-meter I've also been able to keep a decent track of calories spent while exercising.

One of the revelations I got when starting to document how much I ate (calories or weight-watcher points, it doesn't really matter), is that exercise does not really matter when losing weight. First, if you're 20 kg overweight like I was, chances are that you're overeating with at least a day or two worth of food per week. A pizza easily covers 80-100% of your recommended calorie intake per day. To balance one day worth of calories, you will need at a significant amount of intensive exercise. Going swimming or running 30 minutes twice a week will not help.

According to the article Why Exercise Won't Make You Thin, exercise will also stimulate hunger, causing you to eat more. (It certainly does for me; I ofter food-hallucinate when I'm running.)

So, while exercising is a good idea for most people, don't expect to lose any weight unless you also change what you eat.


Johan A said...

Definitely my experience too. To be honest, I can't understand why the myth about exercising to lose weight persists. Tables showing how many calories you burn when exercising and how many calories food and snacks contain are widely available.

Is it because people are prepared to exercise more, but reluctant to change their diet?

Sure, exercise is needed to stay healthy, but it doesn't help you much in losing weight.

JesperE said...

Definitely. Also, if you don't document what you eat and how much you exercise, it is very easy to fool yourself about it. That's much harder to do when you're writing down actual numbers on paper.