Some scientists are re-thinking the old belief that food before exercise is a good idea. Research seems to indicate that if you exercise without eating beforehand, your body will burn fat more efficiently. When carbohydrates aren't available to be burned for energy, your body will burn fat instead.
"Several studies suggest exercising while your body is low on food may be a good way to trim excess fat. In a recent paper, European researchers found that cyclists who trained without eating burned significantly more fat than their counterparts who ate."
It is thought that this method of exercising without eating beforehand is best done before having breakfast. The reason for this is that the presence of carbohydrates will inhibit fat metabolism for about six hours after consumption. Training without eating, before having breakfast is the best way around this.
Diabetics may especially benefit from this practice because it is thought that training without eating will better enable diabetics to control their insulin levels.