Back in the fifties, there was a big debate whether exercise was good for you.
People feared that exerting themselves through exercise would actually do more harm than good. Gradually, this opinion shifted, and by today the consensus among medical experts is that exercise is a plus. It improves vital signs ranging from blood pressure to cholesterol to heart rate and can reduce your risk of cancer and type-2 diabetes.
The consensus today is also that exercise helps you lose or maintain body weight. But there are big questions as to how much is needed for weight control, and some even question whether exercise has a meaningful impact on weight to begin with.
In Good Calories, Bad Calories, author Gary Taubes suggests that exercise may do little to change our weight: when we exercise, our body responds by demanding that we eat more food. And when we don’t exercise, the body asks for less food. The net result may be a wash. While I find this true from personal experience–I tend to weigh at least as much when I’m exercising as when I’m not–this theory has practical limits. I lost significant weight training for (and running) a marathon several years ago. Though I ate far more while training than I normally would–post-run trips to the candy machine were commonplace–I simply couldn’t eat enough to keep up with the calories I’d burn on 15-mile training runs.
And a study published in the Archives of Internal Medicine back in 2008 found similar results. The study followed a number of women who maintained a certain level of exercise for two years, and determined how much weight they gained or lost. Those who exercised the often-recommended half hour a day, for four days a week, as a group saw little meaningful weight loss. But those who exercised nearly an hour a day, five days a week, saw up to a 10% decline in body weight.
These results are intuitive: if exercise helps you to lose weight, then more exercise should help you to lose more weight. And there seems to be little question that, if you are overweight and aren’t exercising, an hour a day or more is likely to trim your waistline. But a big question remains how much benefit you receive from exercising the half hour a day, several times a week, that doctors often recommend.
If Taubes and this 2008 study are correct, the answer is apt to be, very little. In which case, unless you have an hour a day (and the necessary energy) to start pouring into your favorite workout, you’re better off looking to dietary changes rather than exercise, to lose weight. My own, entirely unscientific, experience certainly confirms this.
But I wouldn’t write off moderate exercise just yet. For one, it still appears that exercise has positive effects on your body (again, ranging from blood pressure to cholesterol to more subtle molecular changes that we don’t fully understand) beyond weight loss. This alone is a good reason to exercise. And second, a higher weight on the scale isn’t necessarily the same as a higher level of unhealthy weight. Looking again at my own unscientific evidence, I typically gain weight if I start running or cycling after a long period of sloth, but I don’t think I’m gaining unhealthy weight. My guess is, after a long period of dormancy, my leg muscles are finally moving again, and I’m restoring muscle (which is denser than fat and thus packs on the pounds) that I’d previously lost. I can gain five to ten pounds, but I don’t think it’s unhealthy weight.
And so the number on your scale could plausibly rise when you start exercising moderately–discouraging you from continuing your regimen–despite the fact that you’re getting healthier, in terms of both vital signs and body composition.
But I think it’s also clear that moderate exercise alone will not cause you to drop significant weight. That, I believe, has to come from the way you eat, and if you tend toward the heavier side you probably have to be tougher on your diet than everyone else. But I believe there are ways to do it, without suffering.
Taubes himself thinks carbohydrate restriction (particularly the elimination of refined carbohydrates, which range from sugar to white bread to white rice) is the way to do it, and it seems to be working for Kate Middleton and J. Lo. I’ve also lost weight with this approach and avoid refined carbohydrates whenever necessary. But veganism (presumably also without refined carbohydrates) does the trick for many people, too. Bill Clinton lost 24 pounds this way for Chelsea’s wedding, and has kept it off. And I don’t think the princess, the American Idol judge or the former president are starving themselves to achieve this. (And I’m not either; I have lost a couple pounds as well while recently following a vegan diet.) Certain foods are bad for us, both for our health and our waistlines. Exercise is great for the former but less clear for the latter.
Have you found that moderate exercise lowers your body weight?