Eating enough to sustain your workout—what to eat pre-workout—should depend upon the type of workout that you plan on doing: high, moderate, or low intensity; or cardio or resistance. Here are some guidelines for any moderate- to high-intensity workouts, whether they are cardio or resistance, because you will need some carbs in your system if you want to perform your best.
Three or four hours before exercising, a large meal is fine (600 calories or more).
Two or three hours beforehand, a smaller meal is suitable (400–500 calories).
One or two hours before, a liquid meal is appropriate (300–400 calories).
About an hour beforehand, a small snack will do (200–300 calories).
* Try not to eat during the last hour before you begin a workout because it promotes excessive use of blood sugar in the initial stages of your workout.