Muscle mass impacts metabolism and weight management significantly as it contributes to a higher basal metabolic rate (BMR). The more muscle a person has, the more calories their body burns at rest, making weight management easier. Additionally, regular strength training can increase muscle mass over time, further enhancing metabolic function. Maintaining a good level of muscle also helps to improve insulin sensitivity, reducing the risk of weight gain and obesity. As such, focusing on building and preserving muscle mass is crucial for effective weight management and overall health.