The body utilizes nutrients during a workout primarily for energy production and muscle repair. As you exercise, stored glycogen from carbohydrates is broken down for immediate energy. Simultaneously, protein serves to repair and build muscle tissues damaged during intense activity. Additionally, fats become a key energy source once glycogen stores are depleted, particularly during longer sessions. The intake of vitamins and minerals plays a crucial role in metabolic processes and hydration is vital to maintain performance and prevent fatigue. Overall, a balanced intake before, during, and after workouts ensures optimal energy levels and recovery.