How Much Protein Do We Actually Need?

The Recommended Dietary Allowance is a population-level nutritional standard.

For protein, the familiar figure is:

0.8 g/kg/day

For a 70 kg person:

56 g/day

For a 95 kg person:

76 g/day

That number is often repeated as though science had determined:

Above this, additional protein has no purpose.

That is not what the RDA means.

The RDA is designed to meet the requirement of nearly all healthy people under its underlying criteria.

A value sufficient to prevent deficiency need not maximize every desirable physiological outcome.

Older muscle becomes less sensitive to a given dose of amino acids.

This phenomenon is often called anabolic resistance.

A younger muscle may respond strongly to a moderate protein meal.

An older muscle may require a somewhat larger amino-acid stimulus to generate the same muscle-protein-synthesis response.

That is one reason several expert groups recommend more protein for older adults.

The PROT-AGE Study Group recommended at least 1.0–1.2 g/kg/day for healthy older adults and 1.2 g/kg/day or more for those who exercise.

Sources [1]

The ESPEN expert group reached essentially the same recommendation: 1.0–1.2 g/kg/day for healthy older adults and 1.2–1.5 g/kg/day when malnutrition or acute/chronic illness increases catabolic stress.

Sources [2]

A 2025 review likewise concluded that at least 1.0–1.2 g/kg/day is supported for healthy aging populations.

Sources [3]

Consider a 200 lb adult.

200 lb ≈ 90.7 kg

At the RDA:

90.7 × 0.8 ≈ 73 g/day

At 1.0 g/kg:

91 g/day

At 1.2 g/kg:

109 g/day

At 1.6 g/kg:

145 g/day

These are not competing answers to exactly the same question.

They correspond roughly to different objectives and levels of evidence.

Exercise, particularly resistance training, stimulates muscle protein synthesis.

Protein provides the amino acids used to build and remodel that tissue.

The two therefore interact.

Reviews of older adults consistently find that increasing protein intake while performing resistance exercise is more effective for preserving or increasing muscle mass and strength than simply adding calories without adequate protein.

Sources [4]

The practical conclusion is straightforward:

Exercise determines much of the demand. Protein supplies material for the adaptation.

Neither replaces the other.

More protein is not linearly better.

If someone increases intake from 40 g/day to 90 g/day, the physiological difference may be substantial.

Going from 90 to 140 may produce a smaller benefit.

Going from 140 to 190 may produce little additional muscle benefit for many people.

Once amino acids are no longer limiting muscle synthesis, additional protein can be oxidized for energy, contribute carbon skeletons to glucose or fat metabolism, and ultimately generate nitrogenous waste eliminated largely as urea.

That does not make high-protein diets inherently harmful.

It does mean the body does not maintain an unlimited warehouse of spare amino acids waiting to become muscle.

Muscle protein synthesis responds acutely to protein-containing meals.

For older adults, recent reviews commonly discuss roughly 25–30 g of high-quality protein per meal, or approximately 0.4 g/kg per meal, as a useful target for producing a substantial anabolic response.

Sources [3]

But this does not mean:

Protein above 30 g in one meal is wasted.

That claim is incorrect.

Protein consumed beyond the amount maximizing immediate muscle protein synthesis still has many metabolic uses.

The more defensible conclusion is:

If maintaining muscle is important, spreading substantial protein doses across multiple meals is probably preferable to eating almost none all day and consuming the entire daily intake at dinner.

The exact optimum remains less certain than popular nutrition graphics imply.

Protein sources differ in:

• essential amino-acid content,
• digestibility,
• leucine content,
• and total nutrient package.

For stimulating skeletal muscle protein synthesis, proteins rich in essential amino acids—and particularly leucine—tend to perform well.

Whey is highly effective because it is rapidly digested, rich in essential amino acids, and relatively leucine-rich.

But ordinary foods can provide equivalent nutritional value when total intake and amino-acid composition are adequate.

A supplement is primarily a convenience.

There is no requirement that adequate protein come from meat or dairy.

Plant-based diets can provide sufficient protein.

However, some plant proteins have lower digestibility, less leucine, or lower amounts of one or more essential amino acids per gram.

Someone eating primarily plant protein may therefore benefit from somewhat larger total servings, greater variety, legumes, soy, grains combined across the diet, and attention to overall intake.

The old idea that complementary plant proteins must be combined within the same meal is unnecessarily rigid.

The body maintains amino-acid pools across meals.

Collagen is protein.

But nutritionally, it is an unusual protein.

Collagen is rich in glycine, proline and hydroxyproline, and relatively poor in several essential amino acids.

It is therefore not equivalent to whey as a muscle-building protein.

If the nutritional goal is simply:

I need another 25 grams of high-quality protein to support muscle protein synthesis,

whey, dairy, eggs, soy or other complete proteins are generally better choices.

Collagen may nevertheless serve a different purpose.

Connective tissues—including tendons, ligaments, cartilage and skin—contain large amounts of collagen.

So the relevant question is not:

Is collagen better than whey?

It is:

Are we targeting muscle protein or collagen-rich connective tissue?

Evidence on collagen supplementation for tendons, joints and connective tissue remains less definitive than marketing often suggests, but there is a plausible biological rationale and active research interest.

Thus collagen may complement rather than replace a high-quality protein diet.

A persistent belief holds that eating more than the RDA inevitably damages the kidneys.

That is too broad.

For healthy people with normal renal function, the evidence does not support the idea that moderately higher protein intake automatically causes kidney disease.

However, people with significant chronic kidney disease may require individualized protein restriction.

The PROT-AGE recommendations explicitly identify severe kidney disease as an important exception to otherwise higher protein recommendations in older adults.

Sources [1]

Thus both slogans are too crude:

“High protein is bad for your kidneys.”

“Everyone should eat 150 g of protein.”

Protein cannot fully protect muscle if overall nutrition is severely inadequate.

During prolonged calorie restriction, the body must obtain energy somewhere.

Adequate protein reduces lean-tissue loss but does not make energy balance irrelevant.

This becomes especially important during aging.

Older adults frequently eat fewer calories because of reduced appetite, illness, medication, dental issues, altered taste, social isolation or deliberate dieting.

If energy intake falls while protein is also low, muscle loss can accelerate.

One clinical review of aging nutrition specifically warns that restrictive diets and inadequate intake can exacerbate sarcopenia.

Sources [5]

Intermittent fasting and adequate protein are not inherently incompatible.

But the narrower the feeding window, the harder it becomes to distribute protein into several effective meals.

For someone concerned about preserving muscle during aging, the tradeoff deserves attention.

A person eating once per day may technically consume 100 g of protein.

But a two- or three-meal pattern could offer more opportunities to stimulate muscle protein synthesis.

That does not prove fasting is harmful.

It means optimizing fasting and optimizing muscle anabolism can sometimes point in different directions.

Here the evidence needs qualification.

Much of the support comes from mechanistic muscle-protein-synthesis studies, observational studies, expert consensus, nitrogen/amino-acid requirement methodologies and intervention trials.

The long-term randomized evidence is not perfect.

A review specifically debating whether older adults should universally be told to exceed the RDA noted that longer-term intervention trials remain comparatively limited.

Sources [6]

Nutrition science frequently moves from:

short-term physiology → plausible recommendation

before decades-long outcome trials exist.

That does not invalidate the recommendation.

It lowers our confidence in precise boundaries.

~0.8 g/kg/day

Likely adequate to meet the conventional minimum requirement for most healthy adults.

I would not deliberately target this as an “optimal muscle aging” intake in an older active adult.

~1.0–1.2 g/kg/day

A well-supported practical target for healthy older adults.

~1.2–1.6 g/kg/day

Reasonable for physically active adults, particularly those resistance training, dieting, or prioritizing muscle retention.

>1.6 g/kg/day

May be useful in specific circumstances, but incremental muscle benefits generally become smaller and the need becomes increasingly individualized.

These are decision ranges, not biological cliffs.