Ask anyone the best way drop a few pounds and chances are you'll hear that if you exercise, you'll lose weight. But many adults who exercise at the gym or run or bike say their weight has remained the same year after year. A Time Magazine article says the basic problem is that while exercise burns calories, it can stimulate hunger. WNYC's Amy Eddings interviewed John Cloud who wrote the article.
Amy Eddings: First of all, you have got to be kidding me! No! For years we've been hearing that key to weight control was diet and exercise, diet and exercise, like peanut butter and jelly, together forever, one linked to the other -- and you're telling me now, no?
John Cloud: Right and let me just begin by saying exercise is not completely useless, in fact you want to exercise for all kinds of reasons for your heart health, for your mental health for your joints.
Eddings: But we want to get thin, John, we want to get taut.
Cloud: In terms of weight loss and exercise, there are a couple things going on. One study I quote at length in this story was a study with a group of women in Louisiana and Texas, 464 women who were recruited to exercise three to four times a week with a personal trainer. Their exercise was very carefully calibrated, their heart rates were measured. This was a serious exercise group. They were followed for six months. Their diets didn't change. In fact, they were told, 'Maintain your standard diet and everything'. They compared this group to a group of women who didn't exercise. All they did was fill out monthly forms detailing any medical symptoms they had.
At the end of the six months, they found that the women who exercised had lost no more weight than the women who all they did once a month was think about their health and their diets. They filled out these forms, which had the effect probably of causing them to eat a little bit less, so that they lost a little bit of weight, too.
The person who runs the study calls this phenomenon 'compensation.' Whether because you are hungrier or you reward yourself when you get home, you tend to eat more when you exercise a lot.
Eddings: If you rule out compensation. if people get honest with themselves and stop overeating after a hard work out, then does exercise help?
'In general, for weight loss, exercise is pretty useless,' Eric Ravussin, chair in diabetes and metabolism at Louisiana State University and a prominent exercise researcher.
Cloud: Sure, but we're not really built very well to do that. You know a lot of people have this up and down roller coaster thing with their weight. They'll either go on a diet or they'll adopt some exercise regimen. In the year 2000, these psychologists published a pretty well-known paper in psychology circles about self control. They observed in this paper that self control is like a muscle. If you go out and go running for an hour, it's going to be much harder to get back home and make decisions about anything really, but particularly about food. You've already done this great thing for yourself. That's just kind of how we're built psychologically.
The other factor here is more physiological. There's a great misconception out there. People say "I'm going to speed up my metabolism. I'm going to change a lot of my fat to muscle and muscle is much more effective at burning calories." Muscle is significantly more effective at burning calories, but you're talking about small amounts here. A pound of muscle is going to burn about six calories a day in a resting body. A pound of fat is gonna burned about two calories in a resting body. You have a difference there of four calories. Let's say that you convert 10 pounds of your fat then to muscle. Then you're going to buy yourself about 40 calories a day. Now 40 calories a day is about what's in a teaspoon of butter. It's a couple of bites of a donut.
Eddings: There seems to be this myth that long runs or spin classes will lead to weight loss. Cardio exercises don't seem to play a big role in weight loss. Is it the type of exercise we're doing? What about interval training? There seems to be some science supporting the fact that interval training is better for weight loss.
Cloud: The thing that happens with cardio is that people tend to overestimate dramatically how many calories you really burn. If you go back and you ask people "Think very carefully about how long you went running and give us an honest answer", people almost always overstate the amount that they ran.
"If Brian Lehrer is biking for two hours in the Adirondacks, he might make it back and think 'Hey you know, I can eat a muffin, or a bunch of ice cream' or something." John Cloud, Time Magazine
And so we've become sort of bad calorie counters. When we get back from a run, I am sure I ran for four miles and that means that I burned X number of calories and I am going to have this muffin or I'm going to have sports drinks. Sports drinks are part of the problem here as well. We feel great license to drink something like Gatorade after you do cardio because you're really really hot and sweaty. With the interval training and with the strength training, you are gonna burn calories, but you are gonna need to do that over such a longer period of time.
I do want to emphasize, both of these things are really important for your health. You do need to do cardio exercise for your heart. You do need to do strength training, especially as you get older to protect your joints. Both of these things are gonna make you feel better mentally. These these things do have an important and really critical role in any kind of health regimen. If Brian Lehrer is biking for two hours in the Adirondacks, he might make it back and think "Hey you know and I can eat a muffin, or a bunch of ice cream or something." That's how the reward mechanism is working.
Listen to the entire interview:
Some of Brian Lehrer's listeners "weigh" in:
Chris Shamburg, Facebook
Hmm..."studies"...you can prove anything with those. I started running/marathon prep and couldn't stop losing weight, but I know people who quickly hit a wall with running and weight loss--individual metabolism plays a big part. Nevertheless exercise and a good diet are just good for you (look better, feel better, live better). I mean 'old school' good diet here--balanced with veggies and fruit and light on sweets and fried food.
The Real Truth from Everywhere! August 10, 2009 - 11:31AM
What is with all the overweight hate? And why do you think that YOUR experience is going to be universal? People are ridiculous about this! Even when people don't engage in compensation, there is no direct relationship between reduced calories and exercise and weight loss.
Ellen Diamond from New York City August 10, 2009 - 11:33AM
In the past month, I heard from my GP and cardiologist that overweight folks who exercise live longer than thin people who don't. I know when I go for a long walk I feel (and sleep) much better.
Vevette Cundari, Facebook
If you burn more calories than you take in, of course you're going to lose weight. If people would show a little self control and not have to "reward" themselves for everything they do, maybe they could lose weight and lead a healthier lifestyle.
Jeff August 10, 2009 - 12:11PM
NPR's health blog gives a more complete picture on this story here