Running on empty may not be such a bad idea after all. Though many athletes eat before training, some scientists say that if you really want to get rid of more fat, you should skip the pre-workout snack.

Several researches propose 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 considerably more fat than their counterparts who ate.

Muscles usually get their energy from carbohydrates, which is why athletes like Lance Armstrong and Michael Phelps scarf down enormous amounts of food before a race. But if you haven’t eaten before exercising, your body doesn’t have many carbohydrates in reserve. That forces it to burn fat instead, scientists say.When you exercise (after fasting), your adrenalin is high and your insulin is low, said Peter Hespel, a professor of exercise physiology at the University of Leuven in Belgium. That ratio is positive for your muscles to oxidize (break down) more fatty acids. In a study published in April, researchers at the University of Birmingham and somewhere else assigned seven people to cycle three days a week, followed by an intense session an hour later without eating. Another seven people followed the same regime, without the instruction to fast.

Though members of the group that didn’t eat performed worse on the intensive training, they burned a higher proportion of fat to carbohydrates than the group that ate. The results were published by Medicine & Science in Sports & Exercise, the journal of the American College of Sports Medicine.

In a 2008 study, Hespel and colleagues tested the effects on men who did endurance training without eating versus those who ate. In the athletes who hadn’t eaten, the researchers found a spike in the amount of proteins needed to process fat, meaning their bodies had been primed through fasting to burn more fat.