Burning calories without stimulating appetite
I’ve posted a few times recently on the challenges of losing weight — in particular, the homeostatic mechanisms that your body uses to fight against any attempt to burn more calories than you consume. For instance, exercising stimulates appetite hormones that prompt you to eat more. So I found the following tidbit in the New York Times interesting:
In a completed but unpublished study conducted in his energy-metabolism lab, [Barry] Braun [of UMass-Amherst] and his colleagues had a group of volunteers spend an entire day sitting. If they needed to visit the bathroom or any other location, they spun over in a wheelchair. Meanwhile, in a second session, the same volunteers stood all day, “not doing anything in particular,” Braun says, “just standing.” The difference in energy expenditure was remarkable, representing “hundreds of calories,” Braun says, but with no increase among the upright in their blood levels of ghrelin or other appetite hormones. Standing, for both men and women, burned multiple calories but did not ignite hunger. One thing is going to become clear in the coming years, Braun says: if you want to lose weight, you don’t necessarily have to go for a long run. “Just get rid of your chair.”
This suggest that all those people trying to work at “stand-up” desks may be onto something. On the other hand, I’m still not completely sold on the general message about exercise and weight loss that is more or less accepted as fact in this article:
“In general, exercise by itself is pretty useless for weight loss,” says Eric Ravussin, a professor at the Pennington Biomedical Research Center in Baton Rouge, La., and an expert on weight loss.
The article then describes one of Ravussin’s studies (which I blogged about back in December) in which one group of subjects lost nearly 10% of their bodyweight, or a pound a week, through exercise alone — which seems to contradict the assertion that exercise is useless for weight loss.
But in the exercising group, the dose of exercise required was nearly an hour a day of moderate-intensity activity, what the federal government currently recommends for weight loss but “a lot more than what many people would be able or willing to do,” Ravussin says.
Oh, now I get it. It’s not that exercise is useless for weight loss — it’s doing a little bit of exercise at a low intensity that is useless. Those are two very different statements. I understand that an hour a day of moderate-intensity exercise is a tall order for people in today’s busy, convenience-driven, nutritionally bankrupt society etc. etc. But that doesn’t mean exercise is useless, it just means that it takes a lot of exercise — more, perhaps, than most people are willing to do — to see appreciable changes.