Muscle mass plays a crucial role in overall metabolism by determining the basal metabolic rate (BMR) — the rate at which the body burns calories while at rest. More muscle means a higher BMR, leading to increased energy expenditure. This allows individuals with greater muscle mass to maintain or lose weight more effectively compared to those with less muscle. Additionally, muscle tissue is metabolically active, which means it requires more calories to sustain than fat tissue. Therefore, increasing muscle mass through resistance training can significantly enhance metabolic efficiency.