The principles of nutrient cycling for fitness focus on balancing nutrient intake with energy expenditure. Consuming a variety of macronutrients and micronutrients at different times can optimize performance and recovery. Key strategies include aligning nutrient timing with exercise schedules to support energy needs and enhance muscle recovery. Additionally, maintaining a well-rounded diet, including carbohydrates, proteins, and healthy fats, ensures the body's nutrient demands are met for improved fitness outcomes.