How much protein does a woman over 50 need per day?
More than the 46 g figure that circulates, which is the RDA applied to a 57 kg reference woman. Expert guidance for older adults sits at 1.0 to 1.2 g per kilogram of body weight a day, and a study using indicator amino acid oxidation put the requirement for women over 65 at 1.29 g/kg.
Key takeaways
- The 46 g figure is 0.8 g/kg applied to a 57 kg reference woman. It is a floor, and it is not your body weight.
- Expert guidance for adults over 65 is at least 1.0 to 1.2 g per kilogram a day, rising with illness.
- A study using indicator amino acid oxidation put the requirement for women over 65 at 0.96 average and 1.29 g/kg to cover nearly everyone.
- That study was small, and it agrees in direction with the guidance rather than replacing it.
- For a 68 kg woman the practical range is roughly 68 to 88 g a day, which is a real change from 46.
The number most women in this age group have heard is 46 g a day. It is worth knowing exactly what that figure is, because it is not what most people think.
Where 46 comes from
It is the RDA of 0.8 g per kilogram of body weight, applied to a reference woman of about 57 kg.
Two problems with using it as a target. The RDA is a floor derived from nitrogen balance, set to prevent deficiency in almost everybody rather than to produce good outcomes for muscle or ageing.3 And 57 kg is a reference figure that may have nothing to do with your body.
So 46 g is the minimum for avoiding a deficit, calculated for somebody else.
What the guidance actually says
| Rate | For a 68 kg woman | |
|---|---|---|
| RDA, the deficiency floor | 0.8 g/kg/day | 54 g |
| PROT-AGE, healthy adults over 65 | 1.0 to 1.2 g/kg/day | 68 to 82 g |
| PROT-AGE, with acute or chronic illness | 1.2 to 1.5 g/kg/day | 82 to 102 g |
| Measured by indicator amino acid oxidation | 0.96 average, 1.29 to cover nearly everyone | 65 to 88 g |
PROT-AGE recommends at least 1.0 to 1.2 g/kg a day for healthy adults over 65, rising with illness, and ESPEN reached the same range independently.24
The study worth knowing about
The last row of that table comes from a study that measured protein requirement in women over 65 using indicator amino acid oxidation, a different method from the nitrogen balance work behind the RDA.
It put the estimated average requirement at 0.96 g/kg and the figure covering nearly everyone at 1.29 g/kg, against 0.66 and 0.80 from nitrogen balance.1 That is roughly 60 percent higher.
Two caveats belong with it, and stating them is the difference between reporting a study and selling one. It was small. And one method producing a higher figure than another is an argument for revising a guideline rather than a revision: the RDA has not moved.
What makes it worth citing anyway is that it agrees in direction with the expert guidance that already exists. Two independent lines of evidence pointing the same way is more persuasive than either alone. The broader argument about whether the RDA is too low covers the methods question properly.
Your number
| Body weight | 1.0 g/kg | 1.2 g/kg |
|---|---|---|
| 55 kg / 121 lb | 55 g | 66 g |
| 63 kg / 139 lb | 63 g | 76 g |
| 68 kg / 150 lb | 68 g | 82 g |
| 77 kg / 170 lb | 77 g | 92 g |
| 86 kg / 190 lb | 86 g | 103 g |
The calculator does this from your weight, age and activity level and shows which recommendation the result came from.
For most women in this group that is somewhere between 65 and 95 g, against a widely repeated 46. The gap is roughly one extra proper serving in the day, and it usually belongs at breakfast, which is where the shortfall almost always lives.
Protein is half of it
Every one of the sources above pairs the intake with exercise rather than offering it alone. ESPEN puts it in the title: protein intake and exercise for muscle function with ageing.4
Two or three sessions a week loading the major muscle groups. Starting after 40 works, and the response to loading exists at every age that has been studied.
Where the general number stops applying
This is reference material about healthy adults. If your kidney function is reduced, if you have liver disease, or if protein is already managed as part of your care, your target is set by the clinician who knows your history and not by a calculator. PROT-AGE itself carves out severe kidney disease explicitly, and that carve-out matters more than any figure above.
More questions about Women over 40
Where does the 46 grams figure come from?
It is the RDA of 0.8 g per kilogram applied to a reference woman of about 57 kg. Two things are wrong with using it as a target: it is a floor set to prevent deficiency rather than a good intake, and it was calculated for somebody else's body weight rather than yours.
Do the recommendations differ for women?
No. Protein recommendations are set per kilogram of body weight and are the same for both sexes. Women's figures come out lower in absolute grams because women are on average lighter, which is arithmetic rather than a different physiology.
Is 100 g of protein a day too much for a woman over 50?
For a 70 to 85 kg woman that is around 1.2 to 1.4 g/kg, which sits inside the expert range for older adults. The Institute of Medicine set no upper limit for protein in healthy adults. If your kidney function is reduced or protein is part of your medical care, the number is set by your clinician instead.
References
- Dietary protein requirement of female adults >65 years determined by the indicator amino acid oxidation technique is higher than current recommendations
- Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group
- Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids
- Protein intake and exercise for optimal muscle function with aging: recommendations from the ESPEN Expert Group
