I started taking the cardio kickboxing classes that my instructor teaches at my school. On the weekends, the wife and I like to stay up late and do whatever .. watch movies, go out with friends, etc. The classes start early on the weekends, so I have to set my alarm to wake up, get ready and go. The problem is that I'm not hungry first thing in the morning. So I go to class without eating. I don't want to carbo load, this is aerobic activity. I know that when doing cardio workouts that you body looks to food recently digested for energy. Once that's burned up, does it go to fat first, then muscles? Or if there's nothing in your stomach, does it go straight to absorbing nutrients from your muscles? If that's the case, how long should I NOT go without eating before working out?