It is hard to believe that you can lose weight quickly without lengthy and intense workouts. There are some wonderful findings about physical activity and weight loss in a new study by researchers at the University of Copenhagen. The study suggests 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 Danish scientists rounded up a group of pudgy and sedentary young men, a segment of the population increasingly common in Denmark, as elsewhere in the world. The group, most in their 20s or early 30s, visited the scientists’ lab to undergo baseline measurements of their aerobic fitness, body fat, metabolic rates and general health. None had diabetes, high blood pressure or heart disease and, while heavy, they were not obese.
The men were then randomly assigned to exercise or not. The non-exercisers, who served as controls, returned to their former routines, with no change to their diets or sedentary ways.
A second group began 13 weeks of almost daily moderate workouts, consisting of jogging, cycling or otherwise sweating for about 30 minutes, or until each man had burned 300 calories (based on his individual metabolic rate).
A third group tackled a more strenuous routine of almost hourlong workouts, during which each man burned 600 calories.
The men were asked not to consciously change their diets, either by eating more or less, and to keep detailed daily food diaries throughout the 13 weeks.
On certain designated days, they also were asked to don sophisticated motion sensors that would measure how active they were in the hours before and after exercise.
At the end of the 13 weeks, the members of the control group weighed the same as they had at the start, and their body fat percentages were unchanged, which is hardly surprising.
On the other hand, 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.
If you want to lose weight based on the findings of this study the best advice is to monitor what you are eating and aim to stay moderately active daily.