Most medical professionals recommend that we get one hour of exercise per day most days of the week — every day, if possible. But as busy parents and working professionals know all too well, finding that hour to devote to exercise can be quite a challenge. In fact, most people cite “not enough time in the day” as one of the biggest obstacles to getting the exercise they need.
Fortunately, one study has found that 30 minutes of exercise may be all you need to get the same health benefits that you’d get from 60 minutes.
Researchers recruited 61 young men (ages 20 to 40) to participate in this study. All the men were healthy, had normal blood pressure and blood sugar levels, and were not taking any medication, but at the same time, moderately overweight and sedentary (not engaged in any regular exercise program).
During the 13-week trial, the men were divided into a sedentary control group, a moderate exercise group (30 minutes of aerobic activity per day for a total of 300 calories burned) and a high exercise group (60 minutes of aerobic activity per day for a total of 600 calories burned).
Researchers instructed the men to engage in any type of aerobic activity they wanted (such as walking, running or cycling) every day, but three days a week, they were told to increase the intensity.
At the end of the intervention period, researchers found that, even though the high exercise group used twice as much energy as the moderate exercise group, both groups lost similar amounts of weight and body fat. Specifically, the high group lost an average of 2.7 kg, or 5.9 lbs, while the moderate group lost an average of 3.6 kg, or 7.9 lbs. Body fat reduction for both groups was about 14%.
In addition, both groups had about the same amount of accumulated energy balance, which is the balance of calories consumed compared to calories burned. The accumulated negative energy balance was approximately 20% worse than expected in the high exercise group and about 80% better than expected in the moderate exercise group.
According to researchers, both exercise regimes “led to identical negative accumulated energy balance when calculated from actual changes in body composition over the intervention period. The resulting weight loss… was comprised exclusively of fat mass, demonstrating that even a modest exercise-induced weight loss can be a meaningful ‘healthy’ weight loss.”
They concluded that just 30 minutes a day of concentrated exercise can provide equally good weight loss as 60 minutes.
Now There’s Really No Excuse to Not Exercise
This is excellent news for those of us who find that an hour is too much time to carve out of our hectic schedules. Almost everyone can find 30 minutes to work out, even if it’s early in the morning before the rest of the family wakes up, or later at night after the kids are in bed, or even during our lunch hour. (Just think — 30 minutes for exercise, 15 minutes to shower and dress, 15 minutes to eat!)
So now there really is no excuse. Get out there and start moving for 30 minutes, and reap the health rewards. If you can find time to exercise for longer than 30 minutes, great. But now we have scientific evidence that shows it’s not necessary, and that even smaller amounts of exercise matter.
 Rosenkilde M et al. Body fat and compensatory mechanisms in response to different doses of aerobic exercise — a randomized controlled trial in overweight sedentary males. Am J Physiol Regul Integr Comp Physiol. 2012 Sep;303(6):R571-9.