How Much Protein Do You Need to Build Muscle? What the Research Shows

If you lift weights and want to build muscle, aim for about 0.7 grams of protein per pound of body weight a day (1.6 g/kg). In the biggest analysis of the research, muscle gains stopped improving at around that point. Going up to 1 g per pound (2.2 g/kg) is a reasonable ceiling if you want to cover every base, but more than that won’t build extra muscle.

To get a number for your own size, age and goal in about a minute, use our free protein calculator. Below, we go through what the research actually shows: how much per day, how much per meal, which protein sources work, and whether timing matters as much as people say.

How much protein per day do you need to build muscle?

The best evidence comes from a 2018 meta-analysis by Robert Morton and colleagues at McMaster University. They pooled 49 randomized trials with 1,863 people who did strength training for at least 6 weeks, some with extra protein and some without (1).

Three findings matter most:

• Protein helps, but training does the heavy lifting. Extra protein added about 0.3 kg (0.7 lb) of fat-free mass on top of what training alone produced, plus a small boost in strength. Useful, not magic.
• Gains leveled off at about 1.6 g/kg a day. Above roughly 1.62 g/kg (0.73 g/lb), extra protein did not add more fat-free mass.
• The upper estimate was 2.2 g/kg. The statistical uncertainty around that 1.6 figure ran from 1.03 to 2.20 g/kg. Because some people may sit at the high end, the authors suggested about 2.2 g/kg (1 g/lb) for anyone who wants to maximize gains.

The International Society of Sports Nutrition (ISSN) lands in the same place. Its position stand says 1.4–2.0 g/kg a day is enough for most people who exercise and want to build or keep muscle (2).

Here is what that looks like at common body weights. The last column is the per-meal amount if you eat 4 protein-containing meals (more on that below).

One caveat: these numbers are per kilogram of total body weight. If you carry a lot of body fat, multiplying your full weight by 2.2 overshoots, because fat tissue doesn’t need protein the way muscle does. Our protein calculator switches to a lean-mass estimate at higher body weights for exactly that reason.

Is 1 gram per pound too much?

Not harmful for healthy people, but more than most need. The old gym rule of “1 gram per pound” works out to 2.2 g/kg, which is the top of the research range, not the middle. If hitting 1 g/lb leaves you force-feeding chicken or skipping vegetables, drop to 0.7–0.8 g/lb. You’ll likely see the same results.

How much protein per meal can your body use?

You’ve probably heard that your body can only “absorb” 20–30 grams of protein at once, and the rest is wasted. That’s not quite right.

A 2018 review by Brad Schoenfeld and Alan Aragon looked at this exact question. Larger doses above 20 g do mean more amino acids get burned for energy, but not all of the extra is lost. Some still goes into building tissue. Their practical advice: about 0.4 g/kg per meal across at least 4 meals, which adds up to at least 1.6 g/kg a day. Using the 2.2 g/kg upper bound would mean up to about 0.55 g/kg per meal (3).

A 2023 study pushed this further. Researchers in Maastricht gave 36 healthy young men either a placebo, 25 g or 100 g of milk protein after a full-body workout, then tracked where the protein went using labeled amino acids. Compared with 25 g, the 100 g dose produced a bigger muscle-building response that lasted more than 12 hours, and it barely raised the amount of amino acids burned for energy (4).

That challenges the idea of a hard per-meal cap. But keep it in context: it was one lab study, in young men, measuring short-term muscle protein synthesis, not muscle growth over months. One author was an employee of a dairy company (FrieslandCampina), though the paper states the company had no role in funding or analysis. The sensible takeaway is that a big protein meal isn’t wasted, so if your schedule only allows 2 or 3 meals, you can still hit your daily target. Spreading protein over 3–5 meals is still the easiest way to get there.

Does protein quality matter? Leucine and complete proteins

Not all protein is equal, at least gram for gram. Muscle building is triggered by the essential amino acids (the 9 your body can’t make), and one of them, leucine, acts like the on switch.

The ISSN recommends that each protein serving contains roughly 700–3,000 mg of leucine along with a full set of essential amino acids, and suggests about 0.25 g/kg or 20–40 g of high-quality protein per serving (2). Animal proteins such as dairy, eggs, meat and fish easily meet that in a normal portion. Whey is especially rich in leucine and digests fast, which is why it’s popular after training.

In practice, if you hit your daily total from varied foods, quality takes care of itself for most people. It matters more if you eat small portions, eat mostly plants, or are older (see below).

Plant vs animal protein: can you build muscle on plants?

Yes, as long as you eat enough of it. Plant proteins tend to have less leucine and are a bit less digestible, so in short lab studies they often produce a smaller muscle-building response per gram. But the long-term results are closer than you might expect.

• A 2021 trial put 19 lifelong vegans and 19 meat-eaters through 12 weeks of supervised strength training, with protein brought up to 1.6 g/kg a day in both groups using protein supplements (whey for the meat-eaters, a plant protein for the vegans). Gains in leg muscle, muscle fiber size and strength were the same in both groups (5).
• A 2021 meta-analysis of 16 randomized trials found protein source did not change gains in absolute lean mass or strength overall. There was a small edge for animal protein in younger adults (under 50), worth about 0.4 kg (0.9 lb) of lean mass (6).

So the evidence is mixed but reassuring. If you’re plant-based, aim for the higher end of the range (closer to 2.0 g/kg), and lean on soy, tempeh, seitan, lentils and pea or soy protein powders, which carry more leucine per serving than most other plant foods.

Does protein timing matter for muscle growth?

Much less than supplement ads suggest. A 2013 meta-analysis of more than 20 trials tested whether eating protein right around your workout made a difference. Once the researchers accounted for how much protein people ate in total, timing had no significant effect on muscle size or strength. Total daily protein was the strongest predictor of results (7).

The ISSN position stand agrees: protein before or after training both work, and the muscle-building effect of a workout lasts at least 24 hours (2). That means there’s no 30-minute “anabolic window” to panic about. We cover this in more detail in the anabolic window myth, and look at the research on a pre-sleep shake in protein before bed.

The simple rule: get your daily total first, spread it over a few meals, and don’t stress about the clock.

Do you need more protein when cutting than bulking?

Yes. When you eat in a calorie surplus to gain weight (bulking), the extra energy itself supports muscle growth, so 1.6 g/kg is usually plenty.

When you diet to lose fat (cutting), your body is more likely to break down muscle for fuel. A 2014 systematic review by Eric Helms and colleagues looked at lean, trained lifters in a calorie deficit. It concluded they likely need 2.3–3.1 g/kg of fat-free mass, scaled upward the leaner they are and the bigger the deficit (8). Note that this is per kilogram of lean mass, not total weight, and the review included only 6 studies, so treat it as a guide for lean athletes rather than a rule for everyone.

The ISSN gives a similar range of 2.3–3.1 g/kg for keeping lean mass during calorie restriction in trained people (2). If you’re losing weight, work out your calorie target with our calorie calculator, then set protein toward the higher end of your range.

How much protein to build muscle after 40?

Older muscles respond less to the same dose of protein, which researchers call anabolic resistance. In Morton’s analysis, the extra benefit from protein supplements shrank with age (1). An expert group (PROT-AGE) recommends at least 1.0–1.2 g/kg a day for people over 65, and 1.2 g/kg or more for those who exercise (9).

If you’re lifting to build muscle, the 1.6 g/kg target still applies and may matter even more, along with bigger per-meal servings. We go deeper on this in how much protein you really need after 40.

What does 140 grams of protein a day look like?

Here’s a sample day for a 190 lb (86 kg) person aiming for about 1.6 g/kg, split into 4 meals of roughly 35 g each. Protein values are approximate, typical label amounts.

Bread, rice, oats and vegetables add a few more grams on top. For a plant-based version, swap in firm tofu, tempeh, edamame, soy milk and a pea or soy protein shake.

A protein shake isn’t required, but it’s a convenient way to fill a gap. If you want one, see our best protein powder picks. That guide contains affiliate links. If you buy through them we may earn a commission, and it doesn’t change our recommendations. See our affiliate disclosure.

Can too much protein hurt your kidneys?

Not if your kidneys are healthy. A 2018 meta-analysis of 28 trials with 1,358 people compared higher-protein diets (at least 1.5 g/kg, 20% of calories or 100 g a day) with normal or lower intakes. Changes in kidney filtration did not differ between the groups, and the authors concluded high protein intakes don’t harm kidney function in healthy adults (10). Its main limitation was an unclear risk of bias in the included trials.

If you already have chronic kidney disease, it’s a different story. Guidelines often call for less protein, so follow your doctor’s or renal dietitian’s advice. We go through the full evidence in high-protein diets and kidney health.

The bottom line

• Aim for 1.6 g/kg (0.7 g/lb) a day. Go up to 2.2 g/kg (1 g/lb) if you want a safety margin, are plant-based, or are older.
• Split it into 3–5 meals of about 0.4 g/kg (25–40 g for most people). Larger servings aren’t wasted.
• Choose leucine-rich sources, and if you eat mostly plants, eat a bit more.
• Eat more protein when cutting, and don’t stress about the anabolic window.
• Protein supports muscle growth, but the stimulus comes from training hard and adding load over time. Our guide to progressive overload covers that side.

Ready to set your own target? Get your daily protein number here, or browse all of our free health tools.

A note on conflicts of interest: one author of the Morton meta-analysis has received grant support and honoraria from the US National Dairy Council, which supported some of the trials it reviewed, and Brad Schoenfeld serves on the scientific advisory board of a protein supplement company (Dymatize). Both papers disclose this.

This article is for education only and isn’t medical advice. Read our medical disclaimer.

When you need an easy way to hit your protein target away from home, our guide to protein bars for on-the-go nutrition covers what to look for.

Make it easy: our free meal plan generator builds a 7-day plan that hits your protein target, with everything, vegetarian and vegan options.

Sources

1. Morton RW, et al. 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. Br J Sports Med. 2018;52(6):376-384. PubMed 28698222
2. Jäger R, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. PubMed 28642676
3. Schoenfeld BJ, Aragon AA. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. J Int Soc Sports Nutr. 2018;15:10. PubMed 29497353
4. Trommelen J, et al. The anabolic response to protein ingestion during recovery from exercise has no upper limit in magnitude and duration in vivo in humans. Cell Rep Med. 2023;4(12):101324. PubMed 38118410
5. Hevia-Larraín V, et al. High-protein plant-based diet versus a protein-matched omnivorous diet to support resistance training adaptations: a comparison between habitual vegans and omnivores. Sports Med. 2021;51(6):1317-1330. PubMed 33599941
6. Lim MT, et al. Animal protein versus plant protein in supporting lean mass and muscle strength: a systematic review and meta-analysis of randomized controlled trials. Nutrients. 2021;13(2):661. PubMed 33670701
7. Schoenfeld BJ, Aragon AA, Krieger JW. The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. J Int Soc Sports Nutr. 2013;10(1):53. PubMed 24299050
8. Helms ER, et al. A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes. Int J Sport Nutr Exerc Metab. 2014;24(2):127-138. PubMed 24092765
9. Bauer J, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc. 2013;14(8):542-559. PubMed 23867520
10. Devries MC, et al. 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. J Nutr. 2018;148(11):1760-1775. PubMed 30383278