The "Body For Life" plan recommends exercising on an empty stomach (so that your body uses stored fat for energy instead of the carbohydrates from food), and then eating something that has protein, complex carbohydrates, and not much fat afterwards. The protein is important to help the body build up muscles that have been challenged by the workout. However, this plan is based on very short, intense workouts rather than the more extended periods you tend to get in cycling.