CN Digital StudioApril Daniels Hussar, SELF magazine
To conduct their study, researchers at the University of Copenhagen divided a group of sedentary, overweight men into three groups, asking them all to keep food diaries. The first group didn't exercise at all, the second group exercised daily for 30 minutes (at a moderate pace that caused them to burn 300 calories) and the third group worked out daily for 60 minutes, at the same intensity as the other group (burning 600 calories per workout).
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Guess who lost the most weight after 13 weeks? The men in the middle! The men in the 30-minute group lost about seven pounds each, which is about 80 percent MORE than what the researchers were expecting. Meanwhile, the men in the 60-minute group lost an average of five pounds each, which was about 20 percent LESS than what the researchers would have predicted.
Mads Rosenkilde, a Ph.D. candidate at the University of Copenhagen and lead author of the study, tells HealthySELF that he was surprised by the results of the study. "What was surprising was that the moderate-dose exercise group had a negative energy balance, i.e., loss of fat mass, that was nearly the double of what could be expected from the amount of calories that they burned while exercising," he says. "Meanwhile, the high-dose exercise group had a negative balance that was ... lower than predicted!"
However, he does point out that both exercise regimes were effective, but the moderate dose of exercise proved MORE effective for losing weight.
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"This is a very interesting study which could have major ramifications for the fitness industry," Jim White, American College of Sports Medicine (ACSM) Certified Personal Trainer, tells HealthySELF. "But before you slash your cardio, it is still early yet," he cautions, explaining that it's possible that the 30-minute-a-day group lost more weight within the time frame of the study because the 60-minute group was too tired to engage in any more activity throughout the day.
In fact, motion sensors worn by all the men showed that the moderate exercisers did engage in more activity throughout the rest of the day than the 60-minute group. "That shows exactly how important all the little things are, like taking the stairs and parking far away from the store," says White.
White says he'd like to see more research before deciding that 30 minutes of exercise a day is the way to go. "This was a single-short term study that needs to be replicated, repeated and tested on a more diverse population, like women and various age groups," he says. "Long-term, these studies may reveal that the 60-minute group will surpass the 30-minute group in terms of weight loss, as the former builds more muscle, which ramps up your metabolism."
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How much exercise should you be aiming for? The ACSM and the U.S. Department of Health and Human Services (HHS) recommend at least 150 minutes (two and a half hours per week, or five 30-minute exercise sessions) of moderate activity per week. "This is a minimum for overall health and fitness," says White.
For weight loss, however, White recommends ramping up to 60-90 minutes a day, five days per week, which can be broken up into smaller increments if the larger blocks are inconvenient.
That being said, any amount of exercise is better than nothing. "If the idea that 30 minutes is all you need gets somebody moving, then I'm all for that," he adds. "I'll take something over nothing any day!"
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