Sarcopenia After 40: Why Muscle Is the Metric That Predicts Your Next Two Decades

Age-related muscle loss begins earlier than most men expect. By the fifth decade it is already underway, and without deliberate effort it accelerates. The clinical term is sarcopenia, and it is one of the most reliable predictors of how the next two decades will go.

Muscle is not cosmetic. It is the primary site of glucose disposal in the body, the principal determinant ofresting metabolic rate, and the structural reserve that protects function, independence and recovery from illness later in life. Lower muscle mass tracks with worse metabolic health, lower testosterone, higher fall and frailty risk, and a poorer long-term cardiovascular profile. A man can lose a meaningful amount of it while his body weight barely changes, because fat quietly replaces what muscle leaves behind.

That is the problem with the bathroom scale. It weighs muscle and fat together and reports a single number that hides the shift underneath. A man can be the same weight at 50 as he was at 40 and be carrying noticeably less muscle and more fat, with all the metabolic consequences that follow.

ADEXA scan measures lean mass directly, separated from fat, and gives a baseline you can track over time. That measurement turns an abstract worry into a number you can act on. The interventions that protect and rebuild muscle are well established: adequate protein, in the region of 1.6 to 2.2 grams per kilogram of body weight depending on goals, and progressive resistance training heavy enough to give the body a reason to keep the tissue. Walking, useful as it is, does not provide that signal.

At Miller Health, lean mass is measured by DEXA as part of theExplore assessment and read by HCPC-registered dietitians alongside bloods and resting metabolic rate, so the plan is built on your actual body composition rather than an assumption. Muscle is the metric most men never measure, and the one that matters most.

The Explore assessment includes a DEXA scan and is £1,950 at 25 Harley Street, London.