Protein and Muscle After Forty: How Much You Actually Need

Somewhere in your forties or fifties, a quiet shift begins. Nothing dramatic — the jar lid is a bit stiffer, the shopping bags feel heavier on the walk from the car, getting up off the floor takes an extra beat. Most of us put it down to age and move on. But underneath those small moments is a real process: we gradually lose muscle tissue as the decades pass. It is normal, it is common, and it is one of the few age-related changes where what you eat and how you move genuinely matter.

Protein sits at the centre of that conversation, and it has become one of the most over-marketed nutrients in the supermarket. So it is worth stepping back from the shakes and the “high protein” stickers and asking the plainer questions: what changes with age, how much protein does the evidence support, and what does that look like on a dinner plate?

What sarcopenia actually is

Sarcopenia is the term for age-related loss of muscle mass, strength and function. The word sounds clinical, but the process is ordinary. From around our thirties or forties, most people begin losing a small amount of muscle each year, and the rate tends to accelerate later in life. Strength usually declines faster than mass — which is why someone can look much the same and still find stairs harder than they used to.

It is not a disease you either have or do not have. It sits on a spectrum, and clinicians increasingly assess it by function — grip strength, walking speed, how easily someone rises from a chair — rather than by muscle size alone. Some people reach eighty with plenty of functional muscle. Others lose ground earlier, particularly after illness, injury or extended bed rest, when muscle can be lost quickly and regained only slowly.

Two things reliably influence the trajectory: whether muscles are being asked to do meaningful work, and whether the body has the raw materials to rebuild. Protein is the raw material.

Why protein needs change with age

The commonly discussed mechanism is what researchers call anabolic resistance. In simple terms, older muscle appears to respond less strongly to the same amount of dietary protein than younger muscle does. A serving that would comfortably trigger muscle protein synthesis at thirty may produce a weaker response at seventy-five. The muscle is not deaf, but it needs to be spoken to more loudly.

Several other things compound this. Appetite often shrinks with age. Dental changes, altered taste, medications and simply cooking for one all push people towards softer, easier, more carbohydrate-heavy meals. Protein foods are often the ones that get skipped — the chop that seems like too much effort, the eggs that feel like a bother for one person.

Evidence in this area generally supports the idea that older adults benefit from somewhat more protein than younger adults, not less — which runs against the common intuition that as we get smaller and less active, we need less of everything.

How much protein does the evidence support?

Here honesty matters more than a tidy number.

Australia’s official Nutrient Reference Values set a Recommended Dietary Intake for protein of roughly 0.75 to 0.85 grams per kilogram of body weight per day for most adults, with a modest increase recommended for adults over seventy. For an eighty-kilogram person, that lands somewhere around 60 to 70 grams a day.

The important caveat — widely made by researchers and dietitians, not a fringe view — is that an RDI is an amount sufficient to meet the requirements of nearly all healthy people in a group. It is a floor built to prevent deficiency, not a target optimised for maintaining muscle and function into later life. Those are different goals, and there is no guarantee the same number serves both.

That is why international expert groups working specifically on protein and older adults, including the PROT-AGE study group and expert panels convened under ESPEN, have recommended intakes above the standard RDI for healthy older people — commonly around 1.0 to 1.2 grams per kilogram per day, with higher figures discussed for those who are unwell or recovering. These are consensus recommendations from panels reviewing the available evidence, not settled fact, and are best read as informed opinion rather than a law of nutrition.

What is genuinely contested

Optimal protein intake for older adults is an active area of debate, and anyone telling you the question is closed is overselling.

Genuine disagreements include how much of the observed benefit comes from protein itself versus the resistance exercise it is usually studied alongside; whether spreading protein evenly across meals outperforms an uneven pattern, or whether total daily intake is what really counts; and whether the amino acid leucine deserves the specific attention it often receives.

There is also a practical tension. Higher targets are easy to write and harder to eat, particularly for a small, older person with a modest appetite. Some researchers argue that pushing very high figures risks displacing vegetables, legumes and wholegrains for uncertain gain.

The honest summary: the direction of the evidence fairly consistently favours older adults getting more protein than the bare minimum, alongside resistance-type activity. The precise number is contested, and reasonable experts land in different places.

Practical ways to get there with real food

Most Australians eat the bulk of their protein at dinner and very little at breakfast. Shifting some of it earlier is usually the single most useful change, and it costs nothing.

A rough working target for a main meal is a palm-sized serve of a protein food, with something meaningful at breakfast and lunch too. For orientation, approximate amounts in familiar foods:

100 g cooked chicken, beef, lamb or pork — around 25 to 30 g protein
A 95 g tin of tuna or salmon — around 20 to 25 g
Two large eggs — around 12 to 13 g
A 170 g tub of Greek-style yoghurt — around 15 to 18 g
250 ml of milk — around 8 to 9 g
100 g firm tofu — around 12 to 15 g
A cup of cooked lentils or chickpeas — around 15 to 18 g
30 g of cheddar — around 7 g
A tablespoon of peanut butter — around 4 g

Some practical ways to spread it out:

Breakfast. Eggs on toast, Greek yoghurt with fruit and nuts, baked beans on wholegrain toast, or porridge made with milk rather than water and topped with a spoon of nut butter.

Lunch. Tinned tuna or salmon through a salad or sandwich, leftover roast meat, a boiled egg or two added to whatever is on the plate, or lentil soup with a wholegrain roll.

Dinner. The meal most people already handle well — meat, fish, chicken, tofu or legumes with vegetables. If cooking for one is the barrier, cook for four and freeze in portions.

Between meals. Cheese and crackers, a tub of yoghurt, a handful of nuts, or milk in your tea and coffee. These small contributions add up more than people expect.

For anyone eating little or no meat, spreading legumes, tofu, tempeh, eggs, dairy, nuts and wholegrains across the day works well — variety across the week matters more than engineering any single meal.

Where supplements fit

Protein powders are a convenience, not a necessity. They are a reasonable tool if appetite is poor, if chewing is difficult, or as an easy way to top up a day that fell short. They are not superior to food, and whole foods bring iron, zinc, B12, calcium and fibre that a powder does not.

If you use one, treat it as part of the day’s intake rather than a replacement for meals. And be sceptical of marketing — “high protein” on a package often accompanies a price premium and not much else.

The other half of the equation

Protein is the building material, but muscle is built in response to being used. Resistance-type activity — bands, weights, bodyweight movements, or carrying and lifting in everyday life — is the signal that tells the body the material is needed. Protein without that signal does considerably less. Australian physical activity guidelines suggest muscle-strengthening activity on at least two days a week, and it is never too late to start.

A necessary caution

General guidance is exactly that — general. People with kidney disease, or any condition affecting how the body handles protein, need individual advice and should follow their own doctor’s or dietitian’s recommendations rather than population-level figures. The same applies if you are managing multiple health conditions.

If you are unsure where you sit, an Accredited Practising Dietitian can look at what you actually eat and suggest a target that fits your body, your appetite and your life.