Monday, September 24, 2012

For Weight Loss, Less Exercise May Be More

A  new study by researchers at the University of Copenhagen  found that exercise does seem to contribute to waist-tightening, provided that the amount of exercise is neither too little nor, more strikingly, too much.
The men who had exercised the most, working out for 60 minutes a day, had managed to drop some flab, losing an average of five pounds each. The scientists calculated that that weight loss, while by no means negligible, was still about 20 percent less than would have been expected given the number of calories the men were expending each day during exercise, if food intake and other aspects of their life had held steady.
Meanwhile, the volunteers who’d worked out for only 30 minutes a day did considerably better, shedding about seven pounds each, a total that, given the smaller number of calories that they were burning during exercise, represents a hefty 83 percent “bonus” beyond what would have been expected, says Mads Rosenkilde, a Ph.D. candidate at the University of Copenhagen who led the study.
That impressive weight-loss windfall for the light-duty exercisers “was a bit of a shock,” he says.And it’s not completely clear from the experiment’s additional data just why participants in that group were so much more successful at dropping pounds than the other men.But there are hints, Mr. Rosenkilde says. Food diaries for the group burning 600 calories a day reveal that they subsequently were increasing the size of their meals and snacks, although the additional caloric intake wasn’t enough to explain the difference in their results. “They probably were eating more” than they jotted down, Mr. Rosenkilde speculates.
They also were resolutely inactive in the hours outside of exercise, the motion sensors show. When they weren’t working out, they were, for the most part, sitting. “I think they were fatigued,” Mr. Rosenkilde says.
The men exercising half as much, however, seemed to grow energized and inspired. Their motion sensors show that, compared with the men in the other two groups, they were active in the time apart from exercise. “It looks like they were taking the stairs now, not the elevators, and just moving around more,” Mr. Rosenkilde says. “It was little things, but they add up.”The overall message, he says, is that the shorter exercise sessions seem to have allowed the men “to burn calories without wanting to replace them so much.” The hourlong sessions were more draining and prompted a stronger and largely unconscious desire to replenish the lost energy stores.