This study of 30 overweight female college students over a 12 week period found that three 10 minute bursts of exercise was as effective as a continuous 30 minute exercise session in terms of weight loss, burning calories, and improving aerobic fitness.

Journal of the American College of Nutrition 2001;20:494-501.

http://www.nlm.nih.gov/medlineplus/...story_4254.html