Why exercise wont make you thin

by barbaragarn

Great article in TIME about how people eat more (and more “junk food”) after exercising.

Have you noticed this effect? I know MANY a time after hockey, I’ve let myself have something I’d normally skip, rationalizing that I just burned about 875 calories for 90 minutes of hockey [url=http://www.nutristrategy.com/activitylist2.htm](chart here).

Selected snippets–

“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.

The basic problem is that while it’s true that exercise burns calories and that you must burn calories to lose weight, exercise has another effect: it can stimulate hunger. That causes us to eat more, which in turn can negate the weight-loss benefits we just accrued. Exercise, in other words, isn’t necessarily helping us lose weight. It may even be making it harder.

“I see this anecdotally amongst, like, my wife’s friends,” [another researcher] says. “They’re like, ‘Ah, I’m running an hour a day, and I’m not losing any weight.'” He asks them, “What are you doing after you run?” It turns out one group of friends was stopping at Starbucks for muffins afterward. “I don’t think most people would appreciate that, wow, you only burned 200 or 300 calories, which you’re going to neutralize with just half that muffin.”

Doesn’t exercise turn fat to muscle, and doesn’t muscle process excess calories more efficiently than fat does?

Yes, although the muscle-fat relationship is often misunderstood. … A pound of muscle burns approximately six calories a day in a resting body, compared with the two calories that a pound of fat burns. Which means that after you work out hard enough to convert, say, 10 lb. of fat to muscle–a major achievement–you would be able to eat only an extra 40 calories per day, about the amount in a teaspoon of butter, before beginning to gain weight. Good luck with that.

Humans are not a species that evolved to dispose of many extra calories beyond what we need to live. Rats, among other species, have a far greater capacity to cope with excess calories… (discussion of useful but complicated “brown fat” here)

After we exercise, we often crave sugary calories like those in muffins or in “sports” drinks like Gatorade. 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.

Many people assume that weight is mostly a matter of willpower–that we can learn both to exercise and to avoid muffins and Gatorade. A few of us can, but evolution did not build us to do this for very long. In 2000 the journal Psychological Bulletin published a paper by psychologists Mark Muraven and Roy Baumeister in which they observed that self-control is like a muscle: it weakens each day after you use it. If you force yourself to jog for an hour, your self-regulatory capacity is proportionately enfeebled. Rather than lunching on a salad, you’ll be more likely to opt for pizza.

Doesn’t exercise do anything? Sure. It does plenty. In addition to enhancing heart health and helping prevent disease, exercise improves your mental health and cognitive ability.

But there’s some confusion about whether it is exercise–sweaty, exhausting, hunger-producing bursts of activity done exclusively to benefit our health–that leads to all these benefits or something far simpler: regularly moving during our waking hours.

In short, it’s what you eat, not how hard you try to work it off, that matters more in losing weight. You should exercise to improve your health, but be warned: fiery spurts of vigorous exercise could lead to weight gain. I love how exercise makes me feel, but tomorrow I might skip the VersaClimber–and skip the blueberry bar that is my usual postexercise reward.

Full article here: http://www.time.com/time/health/article/0,8599,1914857,00.html

Do YOU eat more than you would, or “badly” after working out?