The more often you exercise, the more calories you burn, right? Not quite, finds a new study. Working out too much can actually make you less active during your non-workout hours—walking the dog, running errands, playing with the kids—resulting in fewer calories burned by the end of the day.
You heard that right: If you work out too much, you’ll actually burn less calories overall.
In the study, 72 women ages 60 to 74 were split into three groups: women who strength trained once a week and did aerobic activity once a week; women who strength trained twice a week and did aerobic activity twice a week; and women who strength trained three times a week and did aerobic activity three times a week. Each workout took about 40 minutes.
When researchers looked at overall energy expenditure throughout the week, the group who worked out four times was the only group who significantly increased their calorie burn—by 294 calories per day. In addition, while everyone improved their fitness and lost a small amount of weight, there weren’t any significant differences between any of the groups.
How is it possible to work out more but burn less calories overall? “The women who worked out six times a week had substantial decreases in their non-exercise energy expenditure—which is walking to the car, going up stairs, walking the dog, anything above your resting energy expenditure that’s not a workout,” says study author John P. McCarthy, PhD, of the University of Alabama at Birmingham. Interestingly, the group who worked out four times a week actually increased this number by 200 calories per day on average.
“Our initial hypothesis was that the six-workouts-per-week group may be overtraining and have a higher level of stress,” McCarthy says. “We didn’t find that at all.” None of the study groups reported significant fatigue or depression, and every group actually reported an increase in vigor.
So what’s going on? Time constraints, McCarthy hypothesizes. “The main complaint from the group that did the six workouts was that it was time-consuming.” In theory, if you’re spending lots of time traveling to the gym and then working out, you’re probably less likely to go for a long walk after dinner or bike to the store instead of driving.
McCarthy’s advice: For older women, four workouts a week is plenty. Make sure to combine cardiovascular training like brisk walking with strength training. Don’t know where to start? Here are The Only 4 Strength Exercises You Need.
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