How Much Protein Do You Actually Need? The Evidence, in Grams

Educational journalism, not medical advice. This guide curates The Beachside Reader’s reporting — general information, not specific to your situation. New to exercise, injured, or managing a health condition? Talk to your own clinician first. How we work →

The number most people are looking for

If you lift weights and want to build or preserve muscle, the best single estimate from the research is about 1.6 grams of protein per kilogram of bodyweight per day. That figure comes from the largest analysis we have: Morton 2018 pooled 49 controlled trials in nearly 1,900 people and found that gains in muscle and strength kept improving as protein rose — but flattened out around 1.62 g/kg/day. Eating more than that did not buy extra muscle in the pooled data. For a 70 kg (154 lb) person, 1.6 g/kg works out to roughly 112 grams a day — not the 280–420 grams the “double your bodyweight in grams” rule of thumb would demand.

Where the bro-science number comes from (and why it overshoots)

The gym-floor standard — “a gram per pound,” or even “two grams per pound” — converts to roughly 2.2 to 4.4 g/kg. The honest reading is that there is no muscle-building penalty for falling well short of those numbers. The plateau in Morton 2018 sits at about 1.6 g/kg, and even allowing for individual variation, the analysis suggested little benefit beyond roughly 2.2 g/kg at the very top of the range. Major position statements land in the same neighbourhood: the Jäger 2017 International Society of Sports Nutrition stand recommends 1.4 to 2.0 g/kg/day for active people building muscle, and Phillips 2011 — a foundational review of athlete protein needs — reached similar conclusions. The takeaway: 1.2–1.6 g/kg covers most people well, and the upper end (around 2.0–2.2 g/kg) is a reasonable ceiling for serious lifters or anyone dieting hard, not a daily requirement.

Why dieting and ageing push the number up

Two situations justify protein at the higher end of the range. The first is fat loss: when you are eating fewer calories, more dietary protein helps protect muscle and keeps you fuller, which is why most evidence-based fat-loss plans skew protein high. The second is age. After about 50, muscle becomes more “resistant” to protein — the same meal triggers less muscle-building than it would in a younger body. The Bauer 2013 PROT-AGE expert position paper recommends that healthy older adults aim for 1.0 to 1.2 g/kg/day, and 1.2 to 1.5 g/kg for those who are ill or recovering — well above the standard adult RDA of 0.8 g/kg. If you are over 50 and trying to stay strong, treat the higher end of this guide’s range as your floor, not your ceiling.

Is high protein safe for your kidneys?

This is the most persistent worry, and for healthy people the evidence is reassuring. Devries 2018 pooled 28 trials and found that higher-protein diets did not meaningfully change kidney filtration in healthy adults compared with lower- or normal-protein diets. On the safety end of the spectrum, Antonio 2015 had trained adults eat an extreme 3.4 g/kg/day for months and observed no harm to measured markers of health — far above anything this guide recommends. The important caveat: this applies to people with healthy kidneys. If you have chronic kidney disease, diabetes-related kidney problems, or any diagnosed renal condition, protein intake should be set by your doctor or a registered dietitian, not a general guide.

Timing matters far less than your daily total

Once your daily total is right, when you eat protein is a minor detail. The popular “anabolic window” — the idea that you must slam a shake within 30 minutes of training — is mostly marketing; the real window is several hours wide, as we explain in the post-workout protein rush is marketing. The one timing lever with modest support is distribution: spreading protein across three or four meals rather than loading it all at dinner, which is the practical point of eating protein at breakfast. And no, branched-chain amino acid supplements are not a shortcut — BCAAs can’t build muscle without the full set of amino acids you get from real food or a complete protein.

How to turn this into your own number

Pick your goal, multiply, and aim for it most days. Maintain or build muscle: 1.2–1.6 g/kg. Lose fat while keeping muscle, or you’re an experienced lifter: 1.6–2.0 g/kg. Over 50: at least 1.0–1.2 g/kg, leaning higher if you train. To convert from pounds, divide your weight by 2.2 first. To see how that protein target fits alongside your carbs, fats, and calories, run your numbers through our macro calculator. Protein is the macro worth getting right — but it works best as part of a whole diet, so it’s also worth making sure you’re getting enough fibre and, if you lift, considering well-evidenced basics like creatine. Get the daily grams roughly right, spread them across the day, and the rest is detail.

References