How much protein do you actually need?

For a healthy adult, the official recommended intake of protein is 0.8 grams per kilogram of bodyweight per day — about 56 grams a day for a 70-kilogram person. But that figure, set by the National Academies' Dietary Reference Intakes, is deliberately a minimum: it was derived to estimate the least protein needed to avoid losing body nitrogen, and it is defined as the amount sufficient for nearly all healthy people, not the amount that is best for them [s1][s3].

Understanding what the number is — and what it is not — resolves most of the confusion, and most of the marketing.

A floor, not a target

The Recommended Dietary Allowance for protein has been essentially unchanged for more than 70 years, and it functions as a public-health floor: enough to keep a healthy adult out of deficiency [s1]. That is a different question from how much protein supports muscle maintenance, appetite control or healthy ageing.

The National Academies also publish a second, wider figure that most people never hear about: the Acceptable Macronutrient Distribution Range, which puts protein at 10 to 35 per cent of total calories [s1]. Notably, the bottom of that range is already higher than the RDA — so the official documents themselves describe protein intake in two different ways, and the higher one leaves substantial room above the deficiency floor [s1].

The case that 0.8 is too low

A body of research argues the RDA understates what is useful. Reviewing the evidence, one group of protein scientists concluded that intakes of at least 1.2 to 1.6 grams per kilogram per day are a more sensible target for optimising health in adults, citing benefits for muscle preservation, satiety and weight management [s2]. The same review reported finding no evidence-based link between higher-protein diets and kidney disease or worse bone health in people with normal kidneys — the two harms most often invoked against eating more protein [s2].

There is a caveat worth stating plainly, and it is the kind content mills skip: some of the most-cited work arguing for higher intakes comes from researchers with food-industry funding. The authors of the review that lays out the RDA-versus-range distinction disclosed support from bodies including the Beef Checkoff and employment by the National Cattlemen's Beef Association [s1]. That does not make their reading of the numbers wrong — the RDA genuinely is a minimum — but the provenance belongs on the table when a "you need more protein" message is this commercially useful.

Who plausibly needs more

Where the evidence for more protein is strongest is not the general young adult but specific groups. Older adults lose muscle with age — sarcopenia — and the case that they benefit from intakes above the RDA is comparatively well developed, as covered in our look at protein targets for older adults. Athletes and people doing resistance training have their own literature, distinct from general nutrition, on how much and when to eat protein around exercise. And the persistent worry that higher protein damages healthy kidneys is addressed directly in our review of the protein-and-kidneys question.

The practical takeaway is a framing, not a dose: 0.8 g/kg is the line below which a healthy person risks running short, not a ceiling and not an optimum, and the honest state of the evidence is that "more than the minimum" is well supported for older adults and trained people and weaker as a blanket claim for everyone. This is informational only and not dietary advice; anyone with kidney disease or another condition that constrains protein intake should be guided by their own clinician, not a population figure.

Sources

• Optimizing Protein Intake in Adults: RDA Compared with the AMDR — Advances in Nutrition, 2017
• Protein "requirements" beyond the RDA: implications for optimizing health — Applied Physiology, Nutrition, and Metabolism, 2016
• Dietary Reference Intakes for Macronutrients (Protein and Amino Acids) — National Academies Press, 2005