Sarcopenia (revision 6)

Sarcopenia is the loss of skeletal muscle accompanied by loss of strength or physical performance. Current consensus definitions place low muscle strength as the primary criterion, with low muscle quantity as confirmation — a deliberate reversal of earlier mass-based definitions.^[1]

The reordering matters for how the topic is discussed in the context of weight reduction. A fall in lean mass measured by body composition assessment is not sarcopenia; a fall in strength or function is the finding that would be.^[1]

Concern about sarcopenia during substantial pharmacological weight loss is reasonable in principle, particularly in older people and those with low muscle mass at baseline, and the evidence addressing it directly is limited.^[2]

Consensus definitions require low muscle strength for a probable diagnosis, confirmed by low muscle quantity or quality, with poor physical performance indicating severity.^[1]

Grip strength is the most widely used screening measure because it is quick, cheap and correlates with strength elsewhere. Its cut-offs are population- and device-specific, as reference intervals generally are.^[1]