Does more muscle mass rev one’s metabolism ? On Sept. 13, 2024, exercise scientist Dr. Milo Wolf delved into the science of this issue, clarifying misconceptions and shedding light on the relationship between muscle mass and basal metabolic rate (BMR) — energy expended at rest. Key Takeaways A higher percentage of fat-free mass generally correlates with an increased BMR. Skeletal muscle tissue is relatively less metabolically active than organ tissues. Athletes with higher fat-free mass often have larger organs, potentially developed alongside their muscle mass. The brain is an exception. Larger organs can contribute to a higher BMR. [Related: New Study Finds the Human Metabolism Has Four Stages ] Understanding Metabolism Metabolism involves all the chemical reactions within the body that convert food into energy. It includes vital functions like breathing, blood circulation, cell repair, and growth. Metabolism comprises the BMR and the energy burned during physic