Muscle mass significantly impacts metabolism as it determines the body's resting metabolic rate (RMR). Higher muscle mass increases calorie expenditure, both at rest and during physical activity, making weight management easier. Muscle tissue consumes more energy than fat tissue, resulting in a more efficient metabolism. Additionally, maintaining or increasing muscle mass through resistance training can promote fat loss and improve body composition. This interplay between muscle mass and metabolism underscores the importance of strength training in overall fitness and health strategies for long-term well-being.