Do women need less protein than men?

This looks like a physiology question and it is an arithmetic one.

The recommendations are per kilogram

Every major recommendation in this field is expressed as grams per kilogram of body weight, and none of them state different rates for men and women.

• Institute of Medicine, 2005: 0.8 g/kg/day for healthy adults.¹
• PROT-AGE, 2013: at least 1.0 to 1.2 g/kg/day over 65, more with illness.²
• Sports nutrition guidance: 1.4 to 2.0 g/kg/day for people training.⁴

A 75 kg woman and a 75 kg man reading any one of those lines land on identical numbers.

So where does the difference come from

From the step where a rate becomes a gram figure. To publish a single number, somebody has to apply the rate to a reference body weight, and the reference woman is lighter than the reference man.

The last two rows are the point. Once you use a real body weight instead of a reference one, the apparent sex difference disappears entirely.

The 46 g figure that circulates so widely in women's health writing is row one of that table, presented as though it were a recommendation for women rather than a worked example. What the number should actually be after 50 has the arithmetic for real body weights.

Why the misreading matters

Because 46 g is a floor applied to a light reference body, and it gets quoted to women who are heavier, older, training, or losing weight, all of which push the requirement up rather than down.

A 70 kg woman over 65 following PROT-AGE is at 70 to 84 g. Told she needs 46, she is being pointed at roughly half of what the guidance for her age group says. That is not a small rounding difference; it is the gap between the deficiency floor and the range associated with maintaining muscle.

What does differ by sex

One thing, and it is a diagnostic threshold rather than a dietary rate.

The revised European consensus on sarcopenia uses sex-specific cut-offs: grip strength under 27 kg for men and under 16 kg for women raises the diagnosis.³ That reflects differences in average muscle mass and strength, and it is a line for identifying a condition, not a statement about what to eat.

There is also a real difference in what happens through midlife rather than in the recommendation: the menopause transition changes body composition in a way that has no male equivalent. That is a reason the topic gets its own attention here, and it does not change the per-kilogram rate.

What to do with this

Ignore any protein figure quoted as a flat number for "women". Take the rate, apply it to your own body weight, and check which situation you are in.

How the daily target is derived has the rates by situation, and the calculator does the arithmetic and shows which recommendation it used.