30 minutes of daily exercise does the trick

http://news.ku.dk/all_news/2012/2012.8/30-minutes-of-daily-exercise-does-the-trick/

2012-08-22
Same effect in half the time

Researchers at the University of Copenhagen have shown that 30 minutes of daily training provide an equally effective loss of weight and body mass as 60 minutes. Their results have just been published in the American Journal of Physiology.