Thirty minutes of daily exercise provide an equally effective loss of weight and body mass as 60 minutes, researchers at the University of Copenhagen have shown.

For thirteen weeks, a research team at the Faculty of Health and Medical Sciences followed 60 heavy but healthy Danish men in their efforts to get into better shape.

Half of the men were set to exercise for an hour a day, wearing a heart-rate monitor and calorie counter, while the second group only had to sweat for 30 minutes. Research results show that 30 minutes of exercise hard enough to produce a sweat is enough to turn the tide on an unhealthy body mass index.

On average, the men who exercised 30 minutes a day lost 3.6 kilo in three months, while those who exercised for a whole hour only lost 2.7 kg. The reduction in body mass was about 4 kg for both groups, reports Mads Rosenkilde, PhD student, Department of Biomedical Sciences.

Moreover 30 minutes of exercise training provide an extra bonus.

Participants exercising 30 minutes per day burned more calories than they should relative to the training program we set for them. In fact we can see that exercising for a whole hour instead of a half does not provide any additional loss in either body weight or fat. The men who exercised the most lost too little relative to the energy they burned by running, biking or rowing. 30 minutes of concentrated exercise give equally good results on the scale, explained Mads Rosenkilde.

Mads Rosenkilde postulates that some of the explanation for the surprising results is that 30 minutes of exercise is so doable that participants in the study had the desire and energy for even more physical activity after their daily exercise session.

In addition, the study group that spent 60 minutes on the treadmill probably ate more, and therefore lost slightly less weight than anticipated.

Their results have just been published in the American Journal of Physiology.