The blogosphere has been abuzz lately about an article in TIME magazine called Why Exercise Won’t Make You Thin.  It is interesting, because we’ve joked about such things before, yet here’s an article in a credible magazine suggesting it.  But before we dig into it, let me mention that the author of this article exercises regularly and talks about how he isn’t losing fat, yet he weighs only 163 pounds.  Unless he’s abnormally short, that’s not a bad weight for an adult male to be at.   I don’t see how he could be considered fat or obese.  Actually, my “ideal weight” is supposedly 190-200 for my height, so 163 seems too skinny to me.  Anyway, let’s get to the article.

First, let’s start with the author’s premise for his hypothesis:

Like many other people, I get hungry after I exercise, so I often eat more on the days I work out than on the days I don’t.  Could exercise actually be keeping me from losing weight? ~ John Cloud

He also quotes some other experts who back his claim: “In general, for weight loss, exercise is pretty useless,” says Eric Ravussin, chair in diabetes and metabolism at Louisiana State University and a prominent exercise researcher.  That sounds extreme to me, but I’ll keep reading.

The notion that we eat more because exercise makes us more hungry and thus exercise makes it harder to lose weight sure sounds like something the “Important Doctor” came up with.  The article also mentions the idea that intense sessions of exercise may cause people to reward themselves by eating what they want.  I can see that — it’s much easier to justify a milkshake or snack if you’ve worked out.

Some scientists imply that it’s evolution’s fault that humans can easily get fat.  We don’t have much “brown fat”.  Rats, among other species, have a lot of it, which turns off their mitochondria (which are the cells’ power plants), so they don’t get an energy boost from eating too much — they just get warmer, which helps the calories burn effortlessly.  So for animals like that, it’s really difficult for them to get fat, even if they overeat.  In contrast, humans can barely overeat and yet gain weight, because unused calories get stored in regular “white fat” cells.

One example cited in the article explains why our compensation for exercise keeps us from losing weight:

A standard 20-oz. bottle of Gatorade contains 130 calories.  If you’re hot and thirsty after a 20-minute run in summer heat, it’s easy to guzzle that bottle in 20 seconds, in which case the caloric expenditure and the caloric intake are probably a wash.  From a weight-loss perspective, you would have been better off sitting on the sofa knitting.

Well, few people knit these days, but I think it would be fair to replace that part of the example with sitting on the sofa playing video games.  So there’s your proof that playing video games can help you lose more weight than running! (That definitely sounds like something from the “Important Doctor”.)

The article also says that self-control is like a muscle, that it gets weaker when you use it too much.  So if you force yourself to jog for an hour, your capacity for self-control becomes weakened, and you’re more likely to eat pizza than a salad.  (Although I’m always more likely to eat pizza than a salad, given those choices.)

Steven Gortmaker, who heads Harvard’s Prevention Research Center on Nutrition and Physical Activity, agrees that exercising makes you more hungry, therefore he’s suspicious of the playgrounds at fast-food restaurants: “Why would they build those?  I know it sounds kind of like conspiracy theory, but you have to think, if a kid plays five minutes and burns 50 calories, he might then go inside and consume 500 calories or even 1,000.”   One study has shown that exercise causes kids to eat an average of 100 calories more than they had just burned.

Of course, some sites have countered the TIME article, with one even saying it is an “Epic Fail”.  The TIME article makes some points, but we don’t have to give in to overeating because we exercise.  And I don’t think self-control is like a muscle from a physiological sense, but the analogy may work if you carry it out further.  The more you resist something, the stronger you get, instead of weaker — after a while.  For example, if you give up cokes, it may be hard for a few days, but eventually you don’t even miss them anymore.  (I know, because I gave them up.)

I reckon what all this debate results in is that you can find a study that backs up whatever lifestyle you want to live.   If you don’t want to exercise, then you shouldn’t, because it makes you gain weight.   But if you want to lose weight, well, it’s hopeless.  (Of course the last one isn’t true — but if you want to blame it on evolution or misinformation or whatever, there’s an excuse.)  To me, it still seems really simple — if you burn more calories than you take in, you will lose weight.  Maybe that seems too-good-to-be-true, but it adds up, if you do the math.