Nutritional changes recommended for athletes during training include increasing caloric intake, optimizing macronutrient distribution, and staying hydrated. Athletes often require more energy to fuel their workouts, so consuming additional calories from a mix of proteins, carbohydrates, and fats is crucial. An emphasis on carbohydrates helps replenish glycogen stores, while protein supports muscle recovery and repair. It's also important to incorporate various nutrient-rich foods to ensure adequate vitamins and minerals. Hydration plays a key role in performance, so athletes should focus on consuming sufficient fluids before, during, and after exercise to maintain peak performance.