Why is muscle mass important for metabolism?

Muscle mass plays a crucial role in metabolism primarily because muscle tissue is metabolically active, meaning it requires more energy to maintain than fat tissue. This is relevant anatomically; skeletal muscle increases the basal metabolic rate (BMR), which is the number of calories the body burns while at rest. When you have a higher proportion of muscle mass, your body continually uses more energy, even when you are not exercising. This is beneficial for weight management and overall metabolic health, as it helps in maintaining a calorie deficit or balance without excessive dietary restrictions.

The other choices do not accurately reflect the relationship between muscle mass and metabolism. For instance, stating that muscle has no effect on metabolism dismisses the significant caloric expenditure associated with muscle maintenance and activity. The claim that fat tissue burns more calories than muscle is incorrect, as fat tissue is less metabolically demanding. Lastly, the notion that only exercise impacts metabolism overlooks the importance of muscle mass itself in influencing metabolism beyond just physical activity.