If you’re inactive

... you're less of what you just ate. Factors that make muscles less sensitive to protein signalling is ageing. Much of the muscle loss takes place during short periods of inactivity, such as bed rest after a knee replacement.

A simple fix is never to feed someone in a hospital bed unless absolutely necessary. Instead, get them up and make them shuffle to their food. The proportion of protein eaten should be higher to ensure sufficient muscle synthesis signals.