Protein and Ageing: Why Your Requirements Go Up, Not Down

Protein requirements do not fall with age. They rise — and the reason they rise is more interesting, and more useful, than the usual telling.

What actually declines, and how fast

The best quantitative synthesis of the muscle ageing literature, Mitchell and colleagues (2012), puts the numbers at roughly 0.47 per cent of muscle mass a year in men and 0.37 per cent in women from cross-sectional data — about 4.7 and 3.7 per cent per decade. Past 75, longitudinal studies show the rate roughly doubling, to around 0.8 to 1.0 per cent a year in men.

But mass is the wrong thing to focus on, and this is the finding that should reframe the whole subject:

Strength is lost two to five times faster than mass. Past 75, strength declines at roughly 3 to 4 per cent a year in men and 2.5 to 3 per cent in women — several times the rate at which muscle tissue disappears.

You are not simply losing muscle. You are losing the quality of the muscle you keep. That distinction changes what you should do about it.

One correction while we are here: the widely circulated claim that you lose 3 to 8 per cent of muscle per decade after 30 sits at the high end of what the quantitative literature supports, and the age at which decline begins is genuinely contested — proposed onsets in the research range from the late twenties to age 60. Anyone quoting a confident single figure is quoting more precision than exists.

Anabolic resistance, and what it really means

Ageing muscle responds less strongly to a given dose of protein. That is anabolic resistance, and it is the physiological reason requirements rise.

The most current synthesis — Kristiansen and colleagues (2026), pooling 46 studies and 1,280 participants — quantifies it. Muscle protein synthesis in the fasted state is modestly lower in older adults. After a meal, the reduction is larger.

Then comes the part that matters most, and it is rarely mentioned: in studies measuring the response after exercise, most found no significant age-related difference at all. The authors concluded that the preserved response to exercise suggests maintained anabolic potential when the right stimulus is provided.

Read that carefully. Anabolic resistance is largely a problem with the response to protein. It is not, to anything like the same degree, a problem with the response to training. Older muscle responds to resistance exercise much as younger muscle does.

The practical consequence is the opposite of what most supplement marketing implies. The primary answer to anabolic resistance is not more protein. It is resistance training, with enough protein to support it.

It is also worth noting what sits on the list of mechanisms alongside ageing itself: immobility and inactivity. Some of what gets attributed to getting older is attributable to moving less.

The trials that should change your mind

This is where an honest article and a marketing article part company, because the evidence that protein alone helps older adults is weak to null.

Ten Haaf and colleagues (2018) pooled eight trials in non-frail community-dwelling older adults taking protein supplements without a concurrent exercise programme. Lean body mass: a mean difference of 0.014 kg — effectively zero. Leg press strength: not significant. Grip strength: negligible. Their conclusion was that there is currently no evidence that protein or amino acid supplementation without concomitant nutritional or exercise interventions increases muscle mass or strength in predominantly healthy elderly people.

Bhasin and colleagues (2018), in JAMA Internal Medicine, ran the cleanest test. Seventy-eight men aged 65 and over were randomised to 0.8 or 1.3 g of protein per kilogram a day for six months, under controlled feeding. The higher intake did not increase lean body mass, muscle performance, physical function, strength or fatigue. The authors called for the protein RDA in older adults to be re-examined — in both directions.

That was a feeding study without a structured training programme, which is exactly the point. It is strong evidence that protein alone is insufficient. It is not evidence that protein does not matter for people who train.

Now the other side. Whaikid and Piaseu (2024) pooled eight studies of protein supplementation combined with resistance exercise in 854 older adults and found meaningful improvements in muscle mass and grip strength — though not in chair-stand time or gait speed, and with wide confidence intervals and their own caveat that the effect on muscle mass remains inconclusive.

Tian and colleagues (2025), a network meta-analysis of 38 trials and 2,610 healthy older adults, put it most directly: combining exercise and protein supplementation is the most effective method for improving muscle mass, strength and physical function. Resistance training alone also produced substantial strength gains against control. Protein alone did not lead.

The synthesis worth carrying away: resistance training is the intervention. Protein is what makes the intervention work better. Anyone selling you protein as a substitute for lifting is selling you something the evidence does not support.

How much, then

Two position stands remain the reference points, and both put older adults well above the general RDA.

PROT-AGE (Bauer and colleagues, 2013) recommends 1.0 to 1.2 g per kilogram a day for healthy older adults, and 1.2 to 1.5 g for those with acute or chronic illness.

ESPEN (Deutz and colleagues, 2014) recommends at least 1.0 to 1.2 g per kilogram for healthy adults over 65, and 1.2 to 1.5 g for those who are malnourished or ill.

Both are now over a decade old and no formal replacement has been issued. Both recommend resistance exercise alongside, and ESPEN is explicit that daily physical activity should be undertaken by all older people for as long as possible.

Both also carry a kidney caveat: protein restriction may be appropriate in severe kidney disease. If that applies to you, this is a question for your doctor.

The per-meal question, and a claim that does not survive

Older adults appear to need more protein in a single meal to fully trigger the muscle-building response. Moore and colleagues (2015) found maximal myofibrillar protein synthesis required about 0.40 g per kilogram per meal in older men against 0.24 in younger men — but, notably, the maximum rate achieved did not differ between the age groups. Older muscle needs a bigger push to reach the same place, not a lower ceiling.

For a 75 kg adult that translates to roughly 30 g of protein per meal across three or four meals, landing at 1.2 to 1.6 g per kilogram a day.

Leucine is the amino acid doing the triggering, and this is where a widely sold conclusion falls apart.

Leucine reliably switches on muscle protein synthesis — that is one of the better-replicated findings in the field. What it has repeatedly failed to do is translate into more muscle over months. Xu and colleagues (2015) pooled nine randomised trials of leucine supplementation in older people. The effect on muscle protein synthesis was large and statistically clear. The effect on lean body mass was not different from placebo, and neither was the effect on leg lean mass. A 2009 trial of three months of leucine supplementation in healthy elderly men found no increase in muscle mass or strength.

The lesson is that older adults need more protein in a meal to fully trigger the response. It is not that they need a leucine or BCAA supplement — those have been tested and have not delivered.

There is a broader methodological point buried in here that is worth making explicit, because it inoculates against a great deal of supplement marketing: acute muscle protein synthesis is a mechanism marker, not an outcome. It is not reliably correlated with actual muscle gain over a training programme. Any product claiming to be clinically proven to boost muscle protein synthesis by some percentage is quoting the marker, not the result.

What to actually do

Lift something heavy, two or three times a week. This is the intervention. Everything else supports it.
Aim for 1.2 to 1.6 g of protein per kilogram a day, higher if you are ill, recovering, or losing weight.
Get roughly 30 g at each meal rather than saving it for dinner. The response threshold is per-meal, and breakfast is where most people fall short.
Skip the leucine and BCAA supplements. They raise a marker and not an outcome.
If your kidneys are compromised, talk to your doctor first.

Food should cover most of this. Where it does not — and hitting 30 g at breakfast defeats a lot of people — a protein powder is a reasonable way to close the gap, and ours will do it. But read the trials above before you convince yourself the powder is the important part. It is not. The training is.