FILE - This is a Thursday, July 27, 2006 file photo of former Tour de France winner Lance Armstrong, eats a piece of coconut cream pie during a seven-day bike ride across Iowa in Sully, Iowa. Running on empty may not be such a bad idea after all. 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. Muscles usually get their energy from carbohydrates, which is why athletes like Armstrong and Michael Phelps eat 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.(AP Photo/Charlie Neibergall, File)