Time magazine's new cover story is titled "Why Exercise Won't Make You Thin." Eric Ravussin, an exercise researcher from Louisiana State University who studies diabetes and metabolism actually says: "In general, for weight loss, exercise is pretty useless." Pardon?!?!?!
As Time's John Cloud writes:
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.
Cloud cites a study from the peer-reviewed journal PLoS ONE (PLoS is the nonprofit Public Library of Science). The study, supervised by a colleague of Ravussin's, Dr. Timothy Church, chair in health wisdom at LSU, randomly assigned into four groups 464 overweight women who didn't regularly exercise. Women in three of the groups were asked to work out with a personal trainer for six months; women in the fourth group were the control and were told to maintain their usual routines. The results?
On average, the women in all the groups, even the control group, lost weight, but the women who exercised - sweating it out with a trainer several days a week for six months - did not lose significantly more weight than the control subjects did.
Cloud supposes, jokingly (?) "The control-group women may have lost weight because they were filling out those regular health forms, which may have prompted them to consume fewer doughnuts."
Of course, exercise has its benefits: Enhancing heart and circulatory health, helping prevent disease, improving mental health and cognitive ability. Cloud points to a study released by the University of Alberta a few weeks ago which found that people with chronic back pain who exercise four days a week have 36% less disability than those who exercise only two or three days a week.
But weight loss is a different issue. As is self-control. Cloud explains:
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.
This strikes me as somewhat questionable, as I — and most people I know — tend to be quite loathe to "undo" any work put in at the gym with high-calorie snacks. But this working-out-makes-you-eat movement even has conspiracy theorists!
Steven Gortmaker, head of Harvard's Prevention Research Center on Nutrition and Physical Activity says, "If you're more physically active, you're going to get hungry and eat more." 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."
In any case, the key seems to be not to be total sloth and a lead a sedentary lifestyle but just to keep on moving. Cloud writes:
Many obesity researchers now believe that very frequent, low-level physical activity - the kind humans did for tens of thousands of years before the leaf blower was invented - may actually work better for us than the occasional bouts of exercise you get as a gym rat. "You cannot sit still all day long and then have 30 minutes of exercise without producing stress on the muscles," says Hans-Rudolf Berthoud, a neurobiologist at LSU's Pennington Biomedical Research Center who has studied nutrition for 20 years. "The muscles will ache, and you may not want to move after. But to burn calories, the muscle movements don't have to be extreme. It would be better to distribute the movements throughout the day."
Of course, since none of this is conducive to working a desk job (blogging for a living included) we're gonna add: Good luck with that.