Food IS fuel. Without significant amounts of carbohydrates, fats, and protein energy can not be stored, broken down, and used to power our bodies for training. Optimal physiological responses can not occur without adequate substrates that come directly from carbohydrates. Our main energy system that is important for events lasting longer than 2 minutes is the Aerobic System. The human body absolutely needs carbohydrates and fats in order to adapt and improve Aerobic Foundation (AF) processing rates, Prolonged Aerobic Capacity (PAC), and Aerobic Rate Capacity (ARC).