Exercising sweet spot?

Exercising too much may actually impede weight loss, a new study suggests.

Researchers at the University of Copenhagen divided 60 slightly overweight men with sedentary lifestyles into three groups—those who wouldn’t exercise at all, those who would exercise in nearly daily workouts in which they burned 300 calories and those who would burn 600 calories—and told them not change their dietary habits, according to SFGate.com.

At the end of 13 weeks, the group that exercised most lost an average of five pounds (20 percent less than the researchers expected) and the moderate-exercise group lost an average of seven pounds (83 percent more than expected). The discrepancy was due in part to muscle gains in participants of the vigorous exercise group, but researchers also found those men ate more and moved around less outside of the gym than the moderate exercisers.

The study’s authors cautioned more research is necessary, as the experiment was short-term and the men were all in their 20s and 30s.