Sunday, April 18, 2010

Throw Away Your Chair

This week there was an interesting article in the New York Times Magazine concerning what role exercise plays in fat loss in relation to diet. The first half of the piece discusses what role, if any exercise plays in fat loss (I prefer fat loss to the more generic term "weight loss"). This jist of it is this from an American College of Sports Medicine study:
The newest science suggests that exercise alone will not make you thin, but it may determine whether you stay thin, if you can achieve that state. Until recently, the bodily mechanisms involved were mysterious. But scientists are slowly teasing out exercise’s impact on metabolism, appetite and body composition, though the consequences of exercise can vary. 
 It goes on to say that in a study those that reduced calories by 25% alone lost the same amount of weight as those that reduced cals by 12.5% and increased caloric expenditure through exercise by 12.5%.

In other words calories in calories out.

But here is the problem. That doesn't differentiate between the intensity, and suggests that the exercise in question was low intensity cardio. And as we know from other research higher intensity exercise tends to raise your metabolism significantly and thus produce greater caloric expenditure over time.

I'll further quote a longer passage from the article that addresses higher intensity exercise and differences in male and female reactions to low intensity cardio:
In one study presented last year at the annual conference of the American College of Sports Medicine, when healthy young men ran for an hour and a half on a treadmill at a fairly high intensity, their blood concentrations of acylated ghrelin fell, and food held little appeal for the rest of that day. Exercise blunted their appetites. A study that Braun oversaw and that was published last year by The American Journal of Physiology had a slightly different outcome. In it, 18 overweight men and women walked on treadmills in multiple sessions while either eating enough that day to replace the calories burned during exercise or not. Afterward, the men displayed little or no changes in their energy-regulating hormones or their appetites, much as in the other study. But the women uniformly had increased blood concentrations of acylated ghrelin and decreased concentrations of insulin after the sessions in which they had eaten less than they had burned. Their bodies were directing them to replace the lost calories. In physiological terms, the results “are consistent with the paradigm that mechanisms to maintain body fat are more effective in women,” Braun and his colleagues wrote. In practical terms, the results are scientific proof that life is unfair. Female bodies, inspired almost certainly “by a biological need to maintain energy stores for reproduction,” Braun says, fight hard to hold on to every ounce of fat. Exercise for many women (and for some men) increases the desire to eat.
In other words low intensity cardio, the kind I see the vast majority of women doing at the gym, has even less of an affect on fat loss than it does in most men. Ironic isn't it?

But research suggests that for those already thin even low intensity exercise can be effective in maintaining weight. No surprise there.

One final interesting bit is that a new ACSM study suggests that standing has big advantages over sitting regarding burning calories:
In a completed but unpublished study conducted in his energy-metabolism lab, Braun 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.”

I couldn't agree with his last statement more. Sitting for extended periods everyday has shown to cause a multitude of back, neck, and hip problems. And it hinders our efforts at having a good physique.

Stand up, move around, stretch. Common sense prevails.

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