A new Danish study has found that people who exercised for just 30 minutes a day lost a third more weight than those who worked out for an hour a day.

The rationale? Scientists believe that the shorter workout stints left subjects with more energy and motivation to live healthier lifestyles, while those who hit the gym for an hour were more likely to feel burned out.

"The subjects in the test group that exercised the least talk about increased energy levels and a higher motivation for exercising and pursuing a healthy everyday life," said study author Dr. Astrid Jesperson of the University of Copenhagen. "They take the stairs, take the dog for an extra walk or cycle to work." In contrast, the subjects "who exercised for one hour a day, after training, felt exhausted, demotivated and less open to making a healthy change," she added.

“We are thus seeing that a moderate amount of exercise will significantly impact the subjects' daily practices.”

The study, published online in the journal Scandinavian Journal of Public Health, monitored 60 moderately overweight but healthy Danish men for 13 weeks. Half of the subjects exercised vigorously for 30 minutes a day by jogging, cycling, or cross training while the other half exercised for a full hour daily. Subjects also responded to interview questions about their feelings during the study period.

On average, the men who worked out 30 minutes a day lost an average of 3.6 kg during the three months, while those exercising longer lost just 2.7 kg.

Other recent research also suggests a big payoff with small doses of exercise. This May, a new study published in the journal PLOS One found that overweight, inactive men can get fitter and healthier with just four minutes of vigorous high-intensity training three times per week.

Stil, another recent study published in the American Journal of Health Promotion found that each additional minute of intense exercise resulted in a small reduction in weight in female subjects.