© 2019 The Authors Sarcopenia is the age-related loss of muscle mass and function that is a major factor in frailty and loss of physical independence. In this rhesus monkey study, the authors investigate delayed aging by caloric restriction (CR) as a means to understand the biology of sarcopenia. They report beneficial changes with CR to reverse aging in muscle at the tissue level. Molecular and cellular assessments point to a role for growth and metabolic pathways in the effects of CR. The impact of CR on metabolism is linked to the retention of muscle mass and physical activity. The authors suggest that in addition to contributing to muscle aging, metabolism may also be an effective target for sarcopenia prevention.