According to a study published today in the Journal of the American Medical Association just 20 minutes of exercise a day can significantly reduce the risk of childhood diabetes. The researchers performed a clinical trial involving 222 overweight children that were assigned to one of three activity groups over a 13 week period. Two of the groups attended an after school exercise program for either 20 minutes or 40 minutes a day and the third group kept their normal routine. The researchers found that just 20 minutes of exercise a day over the course of a few months reduced body fat, increased fitness and reduced markers for diabetes risk compared to children that had no activity at all. The study found that race and sex had no effect on their results. The children who got 40 minutes of exercise a day did even better, with even less body fat and a lower diabetes risk. The study also revealed that the benefits of exercise were present even without making dietary changes.