Ideally, you should have some form of fuel in your system before you work out. Eating an easily digested carbohydrate an hour or so before you hit the gym ensures that you’ll have enough energy in the tank to get through your program. Try fruit and yogurt or toast and peanut butter; not too much or you’ll feel sluggish and heavy.
If, however, you exercise first thing in the morning, eating before your workout may not be an option. Many people find that they can tolerate cardio on an empty stomach, but need fuel to get through a strength training session. Experiment with the types of food and the timing of your pre-workout meal to discover what works best for you.