Energy comes from carbohydrate, fat and protein. Although some vitamins help the body to use energy, these vitamins are easily obtained from a high carbohydrate diet that includes a variety of foods from the four food groups. It is very important to re-fuel with a high carbohydrate meal or snack as soon as possible after an activity. Although it takes at least one or two days after a hard workout to fully refill the carbohydrate stores, athletes should start consuming carbohydrates within 15 minutes after the activity. The energy from excess protein and amino acid supplements is simply stored by the body as fat - not as muscle.
Athletes get enough protein in their normal diet to allow for muscle growth.
Generally, very little energy for an event is supplied by the pre-event meal. The goals of this meal are physical comfort and mental alertness. Before an event, eat mostly carbohydrates with small amounts of protein and fat. Only eat enough to avoid hunger during the event. Drink plenty of fluids and always eat familiar foods.