What is sarcopenia?

Sarcopenia is the loss of skeletal muscle mass and strength that comes with age. The revised European consensus diagnoses it on strength first rather than on weight: grip strength below 27 kg for men or 16 kg for women is the trigger, confirmed by a measure of muscle quantity. It can sit inside a perfectly normal body weight.

Key takeaways

The revised European consensus (EWGSOP2) made low muscle strength the primary characteristic of sarcopenia. Low muscle quantity confirms the diagnosis rather than starting it.
The strength cut-offs are grip strength below 27 kg for men and below 16 kg for women, or taking more than 15 seconds to rise from a chair five times.
Gait speed at or below 0.8 m/s is used as an indicator of severity, not as the thing that makes the diagnosis.
Because it is defined on strength, sarcopenia is invisible on a bathroom scale. Someone at a stable weight can be losing muscle and gaining fat at the same time.
In the SWAN cohort lean mass began falling during the menopause transition while the rate of fat gain doubled, which is why midlife is the relevant window rather than old age.

Sarcopenia is the clinical name for losing skeletal muscle mass and strength as you age. It turns up in articles about protein constantly, usually as a word that sounds alarming and is never actually defined. It has a precise definition, and the shape of that definition is the most useful thing about it.

Strength first, not weight

In 2019 the European Working Group on Sarcopenia in Older People published a revised consensus, usually shortened to EWGSOP2. The headline change was which measurement comes first.

Low muscle strength became the primary characteristic. Low muscle quantity and quality moved to a confirming role: they are what you measure once weak strength has raised the question, not what raises it.¹

That ordering exists because strength turned out to predict outcomes better than mass does. Two people can carry the same amount of muscle and be very different in what they can do with it, and it is the doing that determines whether somebody can get off the floor.

The consequence for anybody reading this at home is worth stating directly: sarcopenia is invisible on a bathroom scale. Losing muscle and gaining fat at the same rate keeps the number in the display exactly where it was.

The numbers the consensus uses

EWGSOP2 publishes cut-off points, and they are unusually concrete for a clinical definition.

	Cut-off	What it does
Grip strength	Under 27 kg for men, under 16 kg for women	Raises the diagnosis
Chair stand	Over 15 seconds for five rises	Raises the diagnosis
Muscle quantity	Low, by DXA or BIA	Confirms it
Gait speed	0.8 m/s or slower	Indicates severity

The EWGSOP2 cut-off points, and what each measurement is for. Strength raises the question; quantity confirms it.

Grip strength and the chair stand are the two that need no equipment beyond a dynamometer and a chair.¹ Neither is a self-diagnosis, but both are easy things to raise with a doctor if standing up has quietly started taking longer than it used to.

Why midlife is the relevant window

The diagnostic criteria are aimed at older adults. The decline they measure does not start there.

In the SWAN cohort, which followed women through the menopause transition, lean mass began falling during the transition itself while the rate of fat gain roughly doubled.² The scale often stays flat through that period, which is exactly the composition change described above, happening a couple of decades before anyone would think to test grip strength.

That is the argument for treating protein as a midlife concern rather than an old-age one. You are defending against a decline that has already started, not preparing for one that has not.

What the research says helps

The expert recommendations are consistent, and they always come in pairs.

PROT-AGE, 2013. At least 1.0 to 1.2 g of protein per kilogram of body weight a day for healthy older adults, rising to 1.2 to 1.5 g/kg with acute or chronic illness.³
ESPEN, 2014. The same range, reached separately, with the other half of the answer stated in the title itself: protein intake and exercise for muscle function with ageing.⁴

Neither substitutes for the other. Protein supplies the material, loading the muscle supplies the signal, and the research on preserving lean mass pairs them almost without exception.

For the intake side, protein for women over 40 covers how the target moves through midlife, and our calculator turns the per-kilogram figure into grams.

Sarcopenia: what it is and how it is diagnosed