How much protein do you actually need?

Protein is the macronutrient people argue about most and measure least. The confusion is genuine, because there are two honest answers to "how much do I need" — a survival minimum and an optimisation target — and they differ by more than double. This guide lays out both, what the evidence actually supports, and what the numbers look like on a plate. The protein calculator does the per-kilogram arithmetic for your own body weight; the reasoning is here. The usual caveat applies throughout: this is general information, not medical advice.

What the official number actually means

The recommended dietary allowance is 0.8 grams of protein per kilogram of body weight per day — 56 g for a 70 kg person. What that number is, precisely, matters: it is the intake estimated to prevent deficiency in nearly all healthy sedentary adults. It is a floor, not a target. It was never derived by asking what intake makes people strongest, most sated, or best at holding on to muscle through a diet or through ageing — questions the research answered later, with larger numbers.

For sedentary adults the floor is genuinely fine. The interesting cases are everyone else: people who lift, people in a calorie deficit, and older adults, for whom the research consistently points higher.

The numbers if you train

The best-known meta-analysis of protein and resistance training (Morton and colleagues, 2018, pooling 49 studies) found muscle-building benefits rising up to about 1.6 g/kg per day, with the upper end of the confidence interval near 2.2 g/kg — which is why "1.6 to 2.2" became the standard athlete range. Above that, more protein stops adding muscle; it is not harmful, just no longer doing the job you bought it for.

Two situations justify the top of the range. Dieting: in a calorie deficit, higher protein (2.0 g/kg and up in lean people cutting hard) measurably protects muscle while fat comes off, and protein is also the most satiating macronutrient — useful when hungry. Ageing: older adults process protein less efficiently ("anabolic resistance"), and expert groups recommend at least 1.0–1.2 g/kg for healthy people over 65 — the population for whom the official floor is most misleading. How those protein calories fit into a whole day's plan is a different question from body weight itself; the calorie calculator and the macro calculator put the pieces together.

Does protein per meal matter?

Less than the internet says, more than zero. The old claim that the body "can only use 20–30 g per meal" overstates a real finding: muscle protein synthesis per meal does plateau around 0.3–0.4 g/kg (roughly 25–40 g for most people), but protein beyond that is not wasted — it is digested more slowly, used elsewhere, and still counts toward the day. The practical reading: spreading intake across three or four meals of 25–40 g is mildly better than one enormous dinner, and chasing precision beyond that is effort the evidence does not reward. The daily total remains the headline number.

What the numbers look like as food

Targets in grams are abstract; plates are not. Rough, useful equivalences:

• Chicken breast: ~31 g per 100 g cooked — a typical breast is 35–45 g
• Eggs: ~6 g each; three eggs ≈ 19 g
• Greek yogurt: ~10 g per 100 g — a 170 g pot ≈ 17 g
• Lentils and beans: ~9 g per 100 g cooked
• Tofu: ~12–15 g per 100 g; firm styles higher
• A scoop of whey: ~24 g, which is why shakes exist — convenience, not magic

A 70 kg lifter aiming at 1.8 g/kg needs 126 g: yogurt and eggs at breakfast (~30 g), a chicken-and-rice lunch (~45 g), lentils or fish at dinner (~35 g), and the gap covers itself with incidental protein from grains and dairy. Written down, it is an ordinary day of food — the target sounds harder than it eats.

The kidney myth and other worries

The persistent worry — high protein damages kidneys — comes from patients with existing kidney disease, who genuinely are advised to restrict protein. In people with healthy kidneys, controlled trials at intakes well above 2 g/kg have not shown harm, and reviews consistently conclude the same. The honest cautions are smaller: protein displaces other food (a diet of chicken and shakes crowds out fibre), and anyone with a diagnosed kidney condition should follow their clinician, not a fitness article. For the training that gives the protein something to do, Tabata: what the 4-minute workout really is covers the short-and-hard end and the one-rep max calculator the strength end.