Extra caution: Chronic kidney disease or reduced kidney function — protein targets are set individually by a clinician, and the expert recommendations for older adults on this page explicitly exclude severe kidney disease (eGFR under 30 mL/min/1.73 m², not on dialysis).
This is educational information, not medical advice.
The protein RDA is 0.8 g per kg of bodyweight — 56 g a day for men, 46 g for women at reference body weight.3 That figure is a floor, not a target. It's the intake that prevents deficiency in nearly all healthy sedentary adults, and it was never built to be a performance goal. If you train, the literature lands at 1.4–2.0 g/kg/day, with gains in muscle flattening out around 1.6.12 If you're over 65, the base moves up to 1.0–1.2 g/kg.8 Below is your number in grams, by bodyweight and goal, with every figure tied to the study it came from.
Key takeaways
- 0.8 g/kg is a deficiency threshold, not a target. It's 56 g/day for men and 46 g for women — derived from sedentary adults at a reference bodyweight, which is why almost nobody who lifts should aim at it.
- If you train, 1.4–2.0 g/kg/day is the sports-nutrition position, and the largest meta-analysis found extra protein stopped adding to fat-free-mass gains at about 1.62 g/kg/day.
- In a calorie deficit, protein goes up, not down — 2.3–3.1 g/kg/day to hold onto lean mass while you lose fat.
- There is no 30-gram absorption cap. A tracer study fed 100 g and measured a bigger, longer anabolic response than 25 g. Spreading protein out is convenient, not compulsory.
- A gram total is meaningless without a bodyweight. 100 g/day is 1.4 g/kg for a 70 kg person and 1.0 g/kg for a 100 kg person — two completely different answers.
Your number, by bodyweight
This is what most protein guidance refuses to give you: an actual number. Find your bodyweight, then read across to the situation you're in. Every band is the published one, cited in the column header.
One honest limitation of any table like this: the bands were derived in trained or normal-weight populations and are applied here to total bodyweight. At higher bodyweights with substantial body fat, practitioners usually apply them to a target or lean bodyweight instead, which lowers the number — sometimes a lot. Adipose tissue doesn't have a protein requirement.
The RDA is a floor, not a target
Nearly every page that answers this question opens with 0.8 g/kg and stops there. The number is correct. The framing is what fails you.
A Recommended Dietary Allowance is defined as the intake that meets the requirements of 97–98% of healthy individuals in a life-stage group.3 For protein, that requirement was established largely through nitrogen-balance work in sedentary adults: the point at which you stop losing more nitrogen than you take in. It answers "how little can a healthy person eat without developing a deficiency," which is a genuinely useful public-health question and a completely different one from "how much should I eat to build or keep muscle."
The absolute grams follow from the same logic. The 56 g and 46 g figures aren't measurements of men and women — they're 0.8 g/kg applied to a reference body weight for each group.3 Weigh more or less than the reference and your own floor moves with you.
The DRI tables also set an Acceptable Macronutrient Distribution Range for protein of 10–35% of total energy in adults.3 That's a much wider door than the RDA implies, and worth remembering: the same body of guidance that gives you 0.8 g/kg also says a third of your calories coming from protein is within range.
How much protein do women need?
The same g/kg bands. This gets muddled because the RDA is published as two gram totals — 56 for men, 46 for women — which reads like a sex-specific requirement. It mostly isn't: both come from the same 0.8 g/kg multiplied by a different reference bodyweight.3 The training band (1.4–2.0 g/kg), the deficit band (2.3–3.1 g/kg) and the older-adult band (1.0–1.2 g/kg) are all expressed per kilogram, so a 60 kg woman who lifts is looking at 84–120 g/day from the same evidence a 60 kg man would use.
Pregnancy and lactation are the real exceptions in the DRI tables, where the RDA rises to 71 g/day.3 If the reason you're asking is the worry that eating this much protein will make you bulky, we take that question apart separately.
If you train: where the evidence actually lands
Here is the number the hospital pages don't print. A systematic review and meta-analysis pooled 49 randomized trials and 1,863 participants doing at least six weeks of resistance training. Protein supplementation on top of training produced 0.30 kg more fat-free mass (95% CI 0.09–0.52) and 2.49 kg more on one-rep-max strength (95% CI 0.64–4.33) than training alone.1 Those are small effects, and their smallness is the finding — protein supplementation is a modest addition to training, not a substitute for it.
The more useful result came from the break-point analysis. Gains in fat-free mass stopped increasing once total daily protein reached about 1.62 g/kg/day (95% CI 1.03–2.20); beyond that, more protein contributed nothing further.1 Two other findings from the same analysis are worth carrying: the effect of supplementation shrank with age (−0.01 kg per year, p = 0.002) and was larger in people already resistance-trained (+0.75 kg, p = 0.03).1
Firm enough to plan around, not firm enough to treat as a cliff edge. The authors reported the 1.62 g/kg break point even though the underlying segmental regression missed statistical significance (p = 0.079) — and they said so.1 Read it as a well-supported target with a wide confidence interval, which is exactly how our muscle growth hub reads it too. Anyone quoting 1.6 as a precise physiological ceiling is stating it harder than the paper does.
The International Society of Sports Nutrition's position stand lands in the same territory from a different direction: an overall daily intake of 1.4–2.0 g protein/kg bodyweight/day "is sufficient for most exercising individuals" to build and maintain muscle.2 For a 70 kg lifter that's 98–140 g/day; 1.6 g/kg would be 112 g. For an 80 kg lifter, 112–160 g, with 1.6 g/kg at 128 g.
Two bands, two methods, one practical conclusion: somewhere between 1.4 and 2.0 g/kg covers you, and there is no published evidence that pushing past roughly 1.6 buys additional muscle.
If you're dieting: protein goes up, not down
The intuitive move in a calorie deficit is to cut everything proportionally. The evidence says do the opposite with protein. The ISSN position stand puts the figure at 2.3–3.1 g/kg/day to maximize retention of lean body mass in resistance-trained people during hypocaloric periods.2 For a 70 kg person, that's 161–217 g/day.
Be honest about what that band is and isn't. It's a recommendation for resistance-trained people who are actively lifting while dieting — it isn't a general weight-loss prescription, and it's high enough that it can collide with the DRI's own 10–35%-of-energy range. At 1,800 kcal, 161–217 g of protein is 36–48% of your calories, above the AMDR's upper bound.3 That's not a safety problem, it's a reminder that these bands come from different frameworks and the top of the deficit band is an athletic ceiling, not a default.
The direct supplementation evidence is more modest than the mechanism suggests, and we'd rather say so. A meta-analysis of eight randomized trials in 246 healthy athletes found whey supplementation reduced fat mass by 0.96 kg (95% CI −1.37 to −0.55) but produced no significant effect on fat-free mass in any subgroup analysed.11 So: "eat more protein while dieting to protect muscle" is a well-reasoned strategy with a plausible mechanism and modest direct trial support. It is not a guarantee, and a shaker of whey is not what stops you losing muscle — the training is.
If you're over 65
The requirement goes up, and the reason is mechanical. Older adults extract more of an ingested protein load in the gut and respond less strongly to what reaches the muscle, so the same grams do less work. The PROT-AGE study group's evidence-based position is 1.0–1.2 g/kg/day for healthy adults over 65, at least 1.2 g/kg/day for those exercising or otherwise active, and 1.2–1.5 g/kg/day for most older adults with acute or chronic illness.8
For a 70-year-old weighing 70 kg, that's 70–84 g/day as a base, and 84 g or more if they're walking, gardening, or lifting. Notice how far that sits above the 56 g the RDA would hand the same person.
The meta-analysis above points the same way from the opposite side: because the benefit of supplementation fell as age rose, older adults need a higher total intake to reach the same place.1
The authors carve out one group: older people with severe kidney disease — an estimated GFR below 30 mL/min/1.73 m², not on dialysis — who may need to limit protein rather than increase it.8 If that's you or a parent, the number on this page is the wrong number. Protein targets in reduced kidney function are set by the clinician managing it, against lab work this article can't see.
Is high protein bad for your kidneys?
For healthy adults, the evidence doesn't support the fear — but two questions get merged here, and only one of them is settled.
A systematic review and meta-analysis compared higher-protein diets (≥1.5 g/kg, or ≥20% of energy, or ≥100 g/day) against lower or normal intakes in adults without kidney disease, analyzing 28 trials and 1,358 participants.9 Both of its numbers matter, because they point different ways. Comparing post-intervention GFR alone, the higher-protein groups sat slightly higher (SMD 0.19, 95% CI 0.07–0.31, p = 0.002). Comparing the change in GFR from before to after, there was no difference between the diets (SMD 0.11, 95% CI −0.05 to 0.27, p = 0.16).9 The authors concluded that higher protein intakes do not adversely influence kidney function in healthy adults — a raised filtration rate is an adaptation to a bigger nitrogen load, not evidence of injury.
A 16-week randomized crossover in resistance-trained men points the same way at the far end of the range: 2.6 ± 0.8 g/kg/day on the habitual diet versus 3.3 ± 0.8 g/kg/day on the high-protein arm, with no changes in blood lipids or markers of kidney or liver function.10 Eleven men completed it, so read it as reassuring rather than definitive.
The second question is genuinely medical. Reduced kidney function is the one setting where "eat more protein" can be the wrong instruction, and where intake is individualized against lab work.8 That's a conversation with the clinician managing it, not a number from an article.
Can you only absorb 30 grams at a time? (No.)
This is the most repeated number in consumer protein advice and it doesn't survive contact with the tracer studies. Here's where it came from and where it broke.
The original finding is real, and narrow. Forty-eight trained young men ingested 0, 10, 20 or 40 g of whey isolate after unilateral leg exercise. Myofibrillar protein synthesis rose 49% at 20 g and 56% at 40 g over the no-protein condition, with no additional stimulation at 10 g — so 20 g was enough to maximally stimulate that measurement in roughly 80 kg trained young men, and 40 g also raised amino-acid oxidation and urea production.5 That is where "20–30 g is all you can use" comes from. Note the conditions: one leg's worth of exercise, one four-hour measurement window.
Change the conditions and the ceiling moves. After whole-body resistance exercise, 40 g of whey stimulated muscle protein synthesis about 20% more than 20 g (0.059 vs 0.049 %/h, p = 0.005) in resistance-trained men.6 Interestingly, the participants' total lean body mass did not explain the response — the amount of muscle you just trained mattered more than how much of it you own.6
And the window is far longer than four hours. A 2023 quadruple-tracer study fed 100 g of protein and found a greater and more prolonged — over 12 hours — anabolic response than 25 g, with dose-dependent incorporation into muscle protein and a negligible impact on protein breakdown or amino-acid oxidation. The authors' conclusion was that the magnitude and duration of the anabolic response "is not restricted" and had previously been underestimated.4
The practical version: there is no absorption cap that throws protein away. A 60 g dinner is not two-thirds wasted. Splitting protein across the day — the ISSN suggests roughly 0.25 g/kg or 20–40 g per meal, every 3–4 hours2 — remains sensible for appetite, satiety and convenience. It just isn't load-bearing. Hitting the daily total matters far more than how you slice it.
Does timing matter? (Less than you were told.)
A multi-level meta-regression tested the "anabolic window" directly, and the honest answer is contained in the gap between its two analyses. A simple pooled analysis, controlling for nothing, showed a small-to-moderate effect of protein timing on hypertrophy and no significant effect on strength. In the full model controlling for covariates, no significant difference remained between timed and control conditions for either outcome — and total daily protein intake was the strongest predictor of effect size.7
That is the whole timing story for most people. Get the daily number right and the clock stops mattering much. The one timing question with its own separate evidence is pre-sleep protein: the ISSN notes that 30–40 g of casein before bed raises overnight muscle protein synthesis.2 Our whey vs. casein comparison covers that difference properly.
Is 100 g a day a lot? Is 30 g too little?
The reason nobody can answer these is that a gram total is meaningless without a bodyweight. Run it through the same arithmetic as the table:
- 100 g for a 70 kg person is 1.43 g/kg — comfortably inside the training band, and generous if you don't train.
- 100 g for a 100 kg person is 1.0 g/kg — below the training band, and only just above the sedentary floor.
- 100 g for a 55 kg person is 1.8 g/kg — near the top of the training band and past the point where more protein added to fat-free-mass gains in the trials.1
Same number, three different verdicts. So "is 100 g a lot" is really "what do you weigh, and are you training."
30 g a day is too little for almost every adult. For a 70 kg person that's 0.43 g/kg — about half the RDA, which is itself only the deficiency floor.3 Thirty grams is a reasonable amount of protein in a meal; as a daily total it's short for anyone above roughly 37 kg.
Where to get it (and when a powder makes sense)
Food first, and it's less work than the supplement aisle suggests. These are USDA FoodData Central figures for the food itself, with the portion arithmetic shown so you can check it.12
| Food | Per 100 g |
|---|---|
| Chicken breast, roasted, meat only | 31 g |
| Canned light tuna in water, drained | 19 g |
| Egg, hard-boiled | 13 g |
| Cottage cheese, 2% milkfat | 11 g |
| Greek yogurt, plain, nonfat | 10 g |
| Lentils, cooked | 9 g |
Add four of those in a day — 150 g of chicken, three eggs, a pot of Greek yogurt, a serving of lentils — and you're at roughly 100 g before counting bread, milk, or anything else on the plate. For a 70 kg person training, that's the bottom of the band reached without a single scoop.
Which is the actual conclusion of this page: protein powder solves a logistics problem, not a physiological one. There's no ingredient in a tub that meat, eggs, dairy, or beans don't have. If you're already landing near your number from food, a powder buys convenience and nothing this page can measure. Most readers here don't need one.
The exception is real and it's specific: you're short against your number and out of appetite, time, or both. Twenty-five grams of protein dissolved in water at 10pm is easier than a chicken breast, and that's a legitimate reason to own a tub. If that's you, the cheapest plain whey that states its protein per serving does the job — the formulation stories are marketing.
If you buy through this link we may earn a commission, at no extra cost to you. It doesn't change the guidance above: if you're already hitting your number from food, a powder adds nothing measurable.
If you want the form question settled before you buy, our whey isolate vs. concentrate comparison covers what the extra money actually buys, and our whey protein guide grades the evidence benefit by benefit.
One cross-cluster note, since it's the other dosing question this audience asks: creatine works nothing like this. It's a fixed 3–5 g/day for almost everyone, with no bodyweight arithmetic once your stores are full — the creatine dosage guide has the detail.
The bottom line
Stop treating 0.8 g/kg as a goal. It's the floor that keeps a sedentary adult out of deficiency, and it was derived for that job. If you lift, aim at 1.4–2.0 g/kg/day and expect nothing extra above about 1.6.12 Dieting while training pushes the requirement up, not down. Over 65, start at 1.0–1.2 g/kg and go higher if you're active.8 Find your row in the table, take the total from ordinary food, and stop worrying about the clock and the 30-gram myth — neither one is the thing standing between you and the number.
This page is educational information, not medical advice.
Frequently asked questions
How much protein do I need per day?
The RDA is 0.8 g per kg of bodyweight — about 56 g for men and 46 g for women — but that's the floor that prevents deficiency in a sedentary adult. If you train, the evidence points to roughly 1.4–2.0 g/kg, with gains flattening out near 1.6 g/kg.
Is 100 g of protein a day a lot?
It depends entirely on what you weigh. For a 70 kg person that's about 1.4 g/kg — mid-range if you train, generous if you don't. For a 100 kg person it's 1.0 g/kg, which is below the training band.
Can your body only absorb 30 g of protein at a time?
No. A tracer study that fed 100 g of protein found a bigger and longer-lasting anabolic response than 25 g, with almost no extra amino-acid burn-off. Spreading protein out is convenient, not compulsory.
How much protein do I need to build muscle?
About 1.4–2.0 g/kg/day alongside resistance training. The largest meta-analysis found gains in fat-free mass stopped increasing at roughly 1.6 g/kg/day, though the authors noted that break point missed statistical significance.
How much protein per day to lose weight?
Higher, not lower. The sports-nutrition position stand suggests 2.3–3.1 g/kg/day during a calorie deficit to help resistance-trained people hold onto lean mass while they lose fat.
How much protein does a 70-year-old need?
Expert consensus is 1.0–1.2 g/kg/day for healthy older adults, and at least 1.2 g/kg/day if they're active. Anyone with significant kidney disease needs their clinician's number, not a general one.
Does it matter when I eat protein?
Much less than how much. When researchers controlled for total daily protein, the apparent benefit of timing it around workouts disappeared, and total intake was the strongest predictor of the result.
Is too much protein bad for your kidneys?
In healthy adults, the evidence says no: a meta-analysis of 28 trials found the change in kidney filtration rate did not differ between higher- and lower-protein diets. Reduced kidney function is a different situation and a medical one.
References
- Morton RW, Murphy KT, McKellar SR, Schoenfeld BJ, Henselmans M, Helms E, Aragon AA, Devries MC, Banfield L, Krieger JW, Phillips SM (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. Br J Sports Med 52(6):376–384. 49 studies, 1,863 participants; FFM +0.30 kg (95% CI 0.09–0.52); 1RM +2.49 kg (95% CI 0.64–4.33); no further FFM gains above ~1.62 g/kg/day. pubmed.ncbi.nlm.nih.gov
- Jäger R, Kerksick CM, Campbell BI, Cribb PJ, et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr 14:20. 1.4–2.0 g/kg/day for exercising individuals; 2.3–3.1 g/kg/day during hypocaloric periods; 0.25 g/kg or 20–40 g per dose every 3–4 h; 30–40 g pre-sleep casein. pmc.ncbi.nlm.nih.gov
- Institute of Medicine (US) Committee on Use of Dietary Reference Intakes in Nutrition Labeling (2003). Dietary Reference Intakes: Guiding Principles for Nutrition Labeling and Fortification — Appendix C, Reference Tables. Table C-4: protein RDA 56 g/day (men 19+), 46 g/day (women 14+), 71 g/day in pregnancy and lactation, footnoted "based on 0.8 g protein/kg body weight for reference body weight." Table C-5: AMDR for protein 10–35% of energy in adults. ncbi.nlm.nih.gov
- Trommelen J, van Lieshout GAA, Nyakayiru J, Holwerda AM, Smeets JSJ, Hendriks FK, van Kranenburg JMX, Zorenc AH, Senden JM, Goessens JPB, Gijsen AP, van Loon LJC (2023). 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 4(12):101324. 100 g vs 25 g: greater and more prolonged (>12 h) anabolic response; negligible impact on breakdown or amino-acid oxidation. pubmed.ncbi.nlm.nih.gov
- Witard OC, Jackman SR, Breen L, Smith K, Selby A, Tipton KD (2014). Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise. Am J Clin Nutr 99(1):86–95. n = 48; myofibrillar MPS +49% at 20 g and +56% at 40 g vs 0 g, no additional stimulation at 10 g, after unilateral leg exercise in ~80 kg trained young men. pubmed.ncbi.nlm.nih.gov
- Macnaughton LS, Wardle SL, Witard OC, McGlory C, Hamilton DL, Jeromson S, Lawrence CE, Wallis GA, Tipton KD (2016). The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein. Physiol Rep 4(15):e12893. 40 g 0.059 ± 0.020 %/h vs 20 g 0.049 ± 0.020 %/h, P = 0.005; total lean body mass did not influence the response. pmc.ncbi.nlm.nih.gov
- Schoenfeld BJ, Aragon AA, Krieger JW (2013). The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. J Int Soc Sports Nutr 10:53. Unadjusted pooled analysis showed a small-to-moderate hypertrophy effect; in the full model controlling for covariates no significant timing effect remained, and total protein intake was the strongest predictor of effect size. pmc.ncbi.nlm.nih.gov
- Bauer J, Biolo G, Cederholm T, Cesari M, et al., PROT-AGE Study Group (2013). 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 14(8):542–559. 1.0–1.2 g/kg/day for adults over 65; ≥1.2 g/kg/day if exercising or active; 1.2–1.5 g/kg/day with acute or chronic disease; severe kidney disease (eGFR under 30 mL/min/1.73 m², not on dialysis) explicitly excepted. pubmed.ncbi.nlm.nih.gov
- Devries MC, Sithamparapillai A, Brimble KS, Banfield L, Morton RW, Phillips SM (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. J Nutr 148(11):1760–1775. 40 articles reviewed in full text, 28 analysed, 1,358 participants; post-intervention GFR SMD 0.19 (95% CI 0.07–0.31, P = 0.002); change in GFR SMD 0.11 (95% CI −0.05–0.27, P = 0.16). pubmed.ncbi.nlm.nih.gov
- Antonio J, Ellerbroek A, Silver T, Vargas L, Peacock C (2016). The effects of a high protein diet on indices of health and body composition — a crossover trial in resistance-trained men. J Int Soc Sports Nutr 13:3. 16-week randomized crossover, 12 enrolled and 11 completing; 2.6 ± 0.8 g/kg/day habitual vs 3.3 ± 0.8 g/kg/day high-protein; no changes in blood lipids or markers of renal or hepatic function. pubmed.ncbi.nlm.nih.gov
- Castro LHA, de Araújo FHS, Olimpio MYM, de B Primo RB, Pereira TT, Lopes LAF, de M Trindade EBS, Fernandes R, Oesterreich SA (2019). Comparative meta-analysis of the effect of concentrated, hydrolyzed, and isolated whey protein supplementation on body composition of physical activity practitioners. Nutrients 11(9):2047. 8 RCTs, 246 healthy athletes; fat mass WMD −0.96 kg (95% CI −1.37 to −0.55, p < 0.001); no significant effect on fat-free mass in any scenario investigated. pmc.ncbi.nlm.nih.gov
- USDA FoodData Central. Protein per 100 g for the whole foods listed: chicken breast, meat only, cooked, roasted (fdcId 171477); tuna, light, canned in water, drained solids (334194); egg, whole, cooked, hard-boiled (173424); cottage cheese, lowfat, 2% milkfat (328841); yogurt, Greek, plain, nonfat (330137); lentils, mature seeds, cooked, boiled (172421). fdc.nal.usda.gov