Protein — what the science says

In a nutshell

0.83 g of protein per kilogram of body weight a day is enough for an adult; people who lift weights can use about twice as much.^1,3
Above about 1.6 g/kg a day, extra protein no longer adds muscle mass during strength training.³
How much protein you eat over the whole day matters more than timing.⁶

1How much protein

Strong evidence 0.83 g/kg a day is enough for adults of all ages, according to the European Food Safety Authority (EFSA) — about 58 g at 70 kg. EFSA also considers twice that amount, which active people commonly eat, to be safe.¹

Expert recommendation 1.0–1.2 g/kg a day is what the PROT-AGE expert group recommends for people over 65, to keep their muscles and strength. Those who exercise should get at least 1.2 g/kg.²

2Muscles and strength training

Strong evidence 1.6 g/kg A summary of 49 studies with 1,863 people: extra protein increased the gains in muscle mass and strength from strength training. But above about 1.6 g per kilogram a day, it no longer added muscle mass.³

Expert recommendation 20–40 g of protein per meal, spread out roughly every 3–4 hours. According to the International Society of Sports Nutrition (ISSN), 1.4–2.0 g/kg a day in total is enough for most people who exercise.⁴

Moderate evidence soy = whey A summary of 9 studies with 266 people: soy protein produced the same gains in strength and muscle mass from strength training as whey and other animal proteins.⁵

3The anabolic window?

Gym lore says you have to eat protein right around your workout, or you will lose your gains.⁶

Moderate evidence the daily total A meta-analysis of protein timing studies: what mattered most for muscle growth was how much protein people ate over the whole day — not whether they ate it right around training.⁶

4When losing weight

Strong evidence −0.87 kg of fat A summary of randomised trials: on a weight-loss diet with more protein, people lost 0.87 kg more fat and 0.43 kg less muscle and other fat-free mass over about 12 weeks than on a diet with a standard amount of protein.⁷

5What about the kidneys?

Strong evidence A summary of randomised trials in adults without kidney disease: with higher protein intake, kidney function (glomerular filtration) changed no differently than with normal or lower intake.⁸

Related articles: Meat, Eggs, Eating around training.

What to take from this

Do the maths: your weight × 0.83 is the minimum; if you lift, aim for about 1.6 g per kilogram.^1,3
Spread protein over 3–4 meals of 20–40 g.⁴
Protein powder is convenient food, not a must — meat, fish, eggs, dairy, legumes or tofu work too.⁵
ForkRep shows how much protein you ate each day under macronutrients.

Sources

Written on 7 Oct 2026, based on studies available at that date. Newer research may change the conclusions.

EFSA NDA Panel (2012). Scientific Opinion on Dietary Reference Values for protein. EFSA Journal 10(2):2557. doi.org/10.2903/j.efsa.2012.2557
Bauer J. et al. (2013). Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. Journal of the American Medical Directors Association 14(8):542–559. doi.org/10.1016/j.jamda.2013.05.021
Morton R. W. et al. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine 52(6):376–384. doi.org/10.1136/bjsports-2017-097608
Jäger R. et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. JISSN 14:20. doi.org/10.1186/s12970-017-0177-8
Messina M. et al. (2018). No difference between the effects of supplementing with soy protein versus animal protein on gains in muscle mass and strength in response to resistance exercise. International Journal of Sport Nutrition and Exercise Metabolism 28(6):674–685. doi.org/10.1123/ijsnem.2018-0071
Schoenfeld B. J., Aragon A. A., Krieger J. W. (2013). The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. JISSN 10:53. doi.org/10.1186/1550-2783-10-53
Wycherley T. P. et al. (2012). Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials. American Journal of Clinical Nutrition 96(6):1281–1298. doi.org/10.3945/ajcn.112.044321
Devries M. C. et al. (2018). Changes in kidney function do not differ between healthy adults consuming higher- compared with lower- or normal-protein diets: a systematic review and meta-analysis. Journal of Nutrition 148(11):1760–1775. doi.org/10.1093/jn/nxy197

This is general information and does not replace a doctor or dietitian. If you have kidney disease, always ask your doctor about your protein intake.