Workout diet - What to eat before & after a workout | 98Fit Plan a workout diet to stay fueled for your exercise goals Whether it is a workout plan for beginners or an expert workout plan, what you eat before and after it is very important to decide its success. Before you workout, a well-charted intake of carbs will improve your performance and keep you going till you are done. Carbs are your source of energy and the more complex carbs you eat before you workout, the higher is the release of energy.