How much protein do I need a day? The three numbers that matter

There are two honest answers, and the gap between them is where all the confusion lives. The official minimum is 0.8 grams of protein per kilogram of body weight a day, which is about 56 grams for a 70 kilogram adult. The amount associated with building muscle while lifting weights is roughly twice that, with the evidence showing no further gains beyond 1.62 grams per kilogram.

How much protein do I actually need in a day?

Start with what the official number is for. The Recommended Dietary Allowance for protein is 0.80 grams per kilogram of body weight per day, and the Estimated Average Requirement sits below it at 0.66.

Those figures were set to prevent deficiency, not to optimise anything. Robert Wolfe and colleagues made the point directly in Advances in Nutrition in 2017: the protein RDA, they argued, would more appropriately be called a recommended minimum intake.

For a 70 kilogram adult, 0.8 grams per kilogram is 56 grams a day. For a 60 kilogram adult it is 48 grams. The published RDA in grams, 56 for adult men and 46 for adult women, comes from applying that rate to reference body weights.

The separate guidance, the Acceptable Macronutrient Distribution Range, allows protein to supply 10 to 35 per cent of your calories, which at 2,000 calories a day is 50 to 175 grams. That is an enormous span, and in 2024 a National Academies letter report was published specifically to reconsider how the range is set.

Why is the official minimum so low?

Because it answers a narrow question: how little protein can a healthy adult eat without losing body nitrogen.

That is a reasonable public health floor and a poor personal target. It says nothing about muscle mass in your sixties, recovery from illness, or what happens when you add resistance training. Wolfe's argument is that treating a minimum as a recommendation is a category error, and that the two reference values, the RDA and the distribution range, are used as though they answer the same question when they do not.

How much protein do I need if I lift weights?

This has one of the cleanest numbers in nutrition research behind it.

Robert Morton and colleagues published a systematic review, meta-analysis and meta-regression in the British Journal of Sports Medicine in 2018, pooling 49 randomised trials with 1,863 participants, all involving resistance training of at least six weeks.

Protein supplementation significantly increased one-repetition-maximum strength by 2.49 kilograms, fat-free mass by 0.30 kilograms, and muscle fibre cross-sectional area. Those effects are real but modest, which is worth saying out loud.

The number everybody quotes comes from a break-point analysis in the same paper: beyond a total protein intake of 1.62 grams per kilogram per day, there were no further training-induced gains in fat-free mass.

So 1.6 grams per kilogram is a ceiling, not a requirement. For a 70 kilogram person that is about 113 grams a day. Going to 200 grams did not help in these trials.

One more finding from that paper is usually left out: the benefit of supplementation got smaller as participants got older, and it was more effective in people who were already resistance trained.

Does the number change as I get older?

Yes, and upward.

The PROT-AGE study group, convened by the European Union Geriatric Medicine Society and led by Jurgen Bauer, published its position paper in the Journal of the American Medical Directors Association in 2013. Its recommendation for people over 65 is an average daily intake of at least 1.0 to 1.2 grams of protein per kilogram of body weight, rising to 1.2 or more for those who are exercising and otherwise active.

The reasoning is physiological. Older adults extract more of an ingested protein dose in the gut and liver before it reaches the muscle, and the muscle itself responds less strongly to the amino acids that do arrive. More protein is needed to produce the same effect.

That makes the official 0.8 grams per kilogram least appropriate for the group most at risk of losing muscle, which matters because muscle and strength in later life track closely with independence. We have written about grip strength as a longevity marker separately.

Is there a limit to how much protein I can use in one meal?

The widely repeated claim is that the body can only use 20 to 30 grams at a sitting and oxidises the rest. A 2023 study tested that directly, and it does not hold.

Jorn Trommelen and colleagues at Maastricht University used a quadruple isotope tracer approach to follow 100 grams of protein against 25 grams after exercise, and published the results in Cell Reports Medicine.

The 100 gram dose produced a greater and longer anabolic response, still measurable beyond 12 hours. Whole-body net protein balance improved more, and synthesis rates rose in muscle, muscle connective tissue and plasma protein. Protein ingestion had a negligible effect on breakdown or on amino acid oxidation rates.

Their conclusion is that the magnitude and duration of the anabolic response is not restricted, and has previously been underestimated.

The practical read is not that you should eat 100 grams in one go. It is that the 30 gram cap was never well founded, so spreading protein across four precisely timed meals is less important than hitting your daily total.

What does that look like in actual food?

These are approximate figures and vary by product, so check labels where it matters.

Cooked chicken breast carries roughly 31 grams of protein per 100 grams. One large egg is about 6 grams. Plain nonfat Greek yoghurt is around 10 grams per 100 grams, so a 170 gram pot is about 17. Cooked lentils come in near 9 grams per 100 grams. Firm tofu varies a lot with the product and the coagulant, from roughly 8 to 17 grams per 100 grams.

Put together, a day at 110 grams is not exotic: Greek yoghurt at breakfast, a chicken or tofu lunch, lentils or fish at dinner, and a couple of eggs somewhere. The people who struggle are usually those eating very little at breakfast, or eating mostly plants without planning for it. Protein-branded desserts are a less efficient route than ordinary food.

Is a high protein diet bad for my kidneys?

In people with healthy kidneys, higher protein intake has not been shown to cause kidney disease. The concern comes from established kidney disease, where protein intake is a genuine clinical question and is managed by a specialist team.

If you have reduced kidney function, diabetes with kidney involvement, or you have been told to watch your protein, this article is not the place to set your target. Speak to the clinician managing it.

Do I need a protein powder?

No. Nothing in Morton's meta-analysis requires a powder; it measured total protein intake, and food counts the same. Powder is a convenience, useful if you find it hard to reach your total, travel a lot, or dislike eating early in the day.

What a powder does not do is add anything a chicken breast lacks. The trials that show a benefit are showing the benefit of more protein, not of a product.

So what number should I actually use?

If you do no resistance training and want a floor, 0.8 grams per kilogram is the official minimum.

If you train with weights and want the muscle you are working for, aim between 1.2 and 1.6 grams per kilogram. There is no evidence of extra benefit above 1.62 in these trials, so there is no point costing yourself money for more.

If you are over 65, at least 1.0 to 1.2 grams per kilogram, and 1.2 or above if you are active. This is the group where the official minimum is most likely to be too low.

And if you have kidney disease, the number is a clinical decision rather than a reading decision.

This article is general information and not medical advice. Speak to a qualified clinician or dietitian about your own intake, especially if you have kidney disease.