If you eat, allow 45 minutes prior to working out.

Trainers, bodybuilders etc all have varying opinions so it really is personal preference. Many say you get a better cardio workout on an empty stomach and better weight lifting performance with a protein shake or snack 45 minutes prior to workout.

Experiment! Find out which your body prefers. If you feel weak or experience muscle fatigue before you have really done any work, then you probably need a snack before hand.