How much protein do you actually need?
By Rick Campbell · Updated · Sourced to primary literature · Not medical advice
Protein has the strongest evidence base of any macronutrient for a specific numerical target, and simultaneously the most confused public conversation. The confusion has a single root: two different numbers, produced for two different purposes, are routinely presented as though they answered the same question. One is a deficiency threshold set by a committee. The other is an optimum for muscle retention and growth, derived from training studies. They differ by a factor of two or more, and neither is wrong.
This guide separates them properly. It covers what the 0.8 grams per kilogram recommendation actually represents and how it was derived, the higher intakes supported by the resistance-training and calorie-restriction literature, what the evidence does and does not say about spreading protein across meals, why the requirement rises rather than falls with age, and the kidney question answered separately for healthy kidneys and for existing disease. It also covers where the evidence stops, because the top of the published range is a good deal lower than the internet assumes.
In brief
- The 0.8 g/kg Recommended Dietary Allowance is the intake at which deficiency is prevented in almost all healthy adults. It is a floor derived from nitrogen balance, not an optimum for anything.
- The resistance-training meta-analytic evidence shows gains in lean mass plateauing at about 1.6 g/kg a day, with the confidence interval extending to roughly 2.2 g/kg.
- A calorie deficit raises the requirement rather than lowering it, because protein is doing the work of protecting lean tissue while total energy is short.
- Adults over about 65 need more protein per kilogram, not less, because ageing muscle responds less to the same dose. The PROT-AGE position paper recommends at least 1.0 to 1.2 g/kg a day.
- In people with healthy kidneys, higher protein intakes have not been shown to impair kidney function. In established kidney disease the picture is entirely different and the intake is a clinical decision.
What the RDA of 0.8 g/kg actually represents
The Recommended Dietary Allowance for protein, set by the Institute of Medicine, is 0.8 grams per kilogram of body weight per day for adults. The FAO, WHO and UNU expert consultation reached a very similar safe level of intake at 0.83 grams per kilogram. Both figures come from nitrogen balance studies, which measure how much nitrogen goes into a person as protein and how much comes out in urine, faeces and other losses. The intake at which those two quantities balance is the estimated requirement.
Two features of that derivation control how the number should be read. First, the balance point is an average: the Estimated Average Requirement sits below the RDA, and the RDA is deliberately set higher so that it covers almost all healthy adults rather than half of them. Second, and more importantly, nitrogen balance is a measure of not losing tissue. It says nothing about whether more protein would support more muscle, better recovery, better satiety or better outcomes in ageing, because those are not what the experiment measured.
So the RDA answers the question it was asked, which was: below what intake do healthy adults start losing nitrogen? It is a floor beneath which problems appear. Reading it as a ceiling above which protein is wasted is a category error, and it is the single most common mistake in this entire subject. An 80 kilogram adult eating 64 grams a day is not deficient. They are also not eating the amount the training literature associates with the best outcomes, which is a different statement about a different question.
The European Food Safety Authority reached the same neighbourhood by the same route in its opinion on dietary reference values for protein, which is worth knowing because it means the figure is not a quirk of one committee in one country. Three independent bodies looking at broadly the same nitrogen balance evidence arrived at broadly the same floor. That agreement is real and it is also narrow: they agreed about the floor, because the floor is what all three were asked about.
| Intake | Grams a day at 80 kg | What it represents | Source |
|---|---|---|---|
| 0.8 g/kg | 64 g | Deficiency floor for healthy adults, from nitrogen balance | Institute of Medicine RDA, 2005 |
| 0.83 g/kg | 66 g | Safe level of intake, the same derivation by a different committee | FAO/WHO/UNU Technical Report 935 |
| 1.0 to 1.2 g/kg | 80 to 96 g | Older adults, to offset reduced muscle protein synthesis response | PROT-AGE position paper, 2013 |
| 1.2 to 1.5 g/kg | 96 to 120 g | Older adults during acute or chronic illness | PROT-AGE position paper, 2013 |
| 1.6 g/kg | 128 g | The point at which resistance-training gains in lean mass plateau | Morton et al. meta-analysis, 2018 |
| Up to 2.2 g/kg | 176 g | Upper bound of the meta-analytic confidence interval | Morton et al. meta-analysis, 2018 |
Where the higher numbers come from
The most useful single piece of evidence on the higher end is a systematic review, meta-analysis and meta-regression by Morton and colleagues, pooling resistance-training studies that supplemented protein. It found that protein supplementation increased gains in lean mass and strength, and that the benefit reached a plateau at about 1.6 grams per kilogram per day. Above that point, the pooled data did not show further gains in lean mass. The confidence interval around the plateau extended to roughly 2.2 grams per kilogram, which is where the commonly quoted upper figure comes from.
Two things about that finding deserve emphasis because they are routinely lost. The plateau applies to lean mass gain in resistance-trained conditions; it is not a claim that nothing above 1.6 does anything for anyone. And the plateau was found in a pooled analysis, which means individuals sat on both sides of it. A confidence interval extending to 2.2 is a statement of uncertainty about where the plateau really lies, not a recommendation to eat 2.2.
The practical reading is that 1.6 grams per kilogram is a defensible general target for someone training with weights, that going to 2.0 or 2.2 is a reasonable hedge against the uncertainty in that estimate and against the specific circumstances discussed in the next section, and that the difference between 1.6 and 2.2 is much smaller in consequence than the difference between 0.8 and 1.6. Most of the available benefit is captured by getting off the floor.
It is also worth being clear about what protein is not doing here. Protein does not cause muscle growth; training does, and protein permits it. Someone eating 2.2 grams per kilogram without a resistance training stimulus is not building muscle, they are simply eating a high-protein diet, which has its own modest merits for satiety and for the thermic effect of food but is not a substitute for the stimulus.
Protein in a calorie deficit
A calorie deficit raises the protein requirement rather than lowering it, which is the opposite of what an intuition about eating less would suggest. The reasoning is straightforward. In a deficit the body is short of energy and will meet that shortfall partly from fat and partly from lean tissue, and the share taken from lean tissue depends on how strongly that tissue is being defended. Protein intake and resistance training are the two things that defend it.
The systematic review by Helms and colleagues examined dietary protein during caloric restriction specifically in resistance-trained lean athletes and made the case for higher intakes, in the region of 2.3 to 3.1 grams per kilogram of fat-free mass per day. That figure is expressed per kilogram of fat-free mass rather than per kilogram of body weight, which is an important distinction that gets lost in summaries. For a lean 80 kilogram athlete carrying twelve per cent body fat, fat-free mass is about 70 kilograms, so the range works out at roughly 162 to 218 grams a day, or about 2.0 to 2.7 grams per kilogram of total body weight.
For someone who is not a lean athlete, the per-body-weight and per-fat-free-mass figures diverge much further, and the per-fat-free-mass version is the more sensible one. A 120 kilogram adult with a high fat mass does not need protein scaled to the fat, which is metabolically inexpensive and does not need defending. Scaling to lean mass, or to a target body weight, gives a more sensible figure and avoids producing intakes that are impractical to eat.
The conditions stack. Someone in a deficit, training with weights, and over 65 is sitting at the intersection of three separate arguments for a higher intake, and the sensible response is to sit near the top of the evidenced range rather than to add the recommendations together. There is no version of this evidence that supports 4 grams per kilogram.
Distribution across meals, and leucine
Muscle protein synthesis responds to a dose of protein in a meal, rises for a few hours and returns to baseline, and the response appears to saturate. That physiology is the basis for advice about spreading protein across the day rather than eating it all at dinner. The question is how much that second-order effect actually matters against the first-order effect of total daily intake.
The controlled work by Areta and colleagues fed the same total daily protein in three different patterns after resistance exercise and measured myofibrillar protein synthesis over twelve hours. An intermediate pattern of moderate doses every few hours produced a greater response than either a small-and-frequent pattern or a large-and-infrequent one. The review by Schoenfeld and Aragon, examining how much protein the body can use in a single meal for muscle building, arrived at practical guidance in the region of 0.4 grams per kilogram of body weight per meal across a minimum of four meals, which lands at about 1.6 grams per kilogram a day.
The mechanism usually invoked is leucine, the branched-chain amino acid that acts as a trigger for the synthetic response. A meal has to clear a leucine threshold to produce a full response, and that threshold is met comfortably by roughly 25 to 30 grams of an animal protein or a well-chosen plant combination. It is much harder to meet from small snacks, or from plant sources eaten in small amounts, because plant proteins generally carry less leucine per gram.
The practical conclusion is modest and worth stating plainly: total daily intake is the first-order variable, and distribution is a second-order refinement worth getting roughly right. Three or four meals each clearing the threshold is sufficient. Breakfast is where most people are short, because a typical cereal or toast breakfast delivers under ten grams. Setting an alarm to drink a shake at 3 a.m. is not supported by anything.
| Pattern | Distribution | Meals clearing the threshold | Verdict |
|---|---|---|---|
| Even split across four meals | 35 g, 35 g, 35 g, 35 g | Four of four | The pattern the controlled evidence supports; nothing further to gain from fiddling |
| Typical Western day | 10 g breakfast, 35 g lunch, 95 g dinner | Two of three | Total is met but one eating occasion misses the dose; breakfast is the fixable one |
| Small and frequent | Eight snacks of 17.5 g | Possibly none | Doses too small to trigger a full response; more effort for a worse result |
| Two large meals | 70 g and 70 g | Two of two | Acceptable if total is met; the upper dose is likely past saturation, which is not harmful |
Older adults, anabolic resistance and sarcopenia
The requirement per kilogram rises with age, which is the opposite of what most people assume and unfortunately also the opposite of what appetite tends to do. The mechanism is anabolic resistance: ageing muscle produces a smaller muscle protein synthesis response to the same dose of protein than younger muscle does. An identical meal therefore accomplishes less, and the arithmetic response is to raise the dose.
The PROT-AGE study group position paper, published by Bauer and colleagues, recommends at least 1.0 to 1.2 grams per kilogram per day for healthy older adults, rising to 1.2 to 1.5 grams per kilogram during acute or chronic illness. Both of those sit above the 0.8 gram RDA, which means that for an older adult the RDA is not a conservative baseline, it is an insufficient one. That is a clinically significant gap and it is not widely known outside geriatrics.
Sarcopenia, the age-related loss of muscle mass and function, is the outcome this is trying to prevent, and protein alone does not prevent it. Resistance training is the necessary stimulus; protein permits the response. The combination of both is well evidenced, the combination of neither is the default, and protein alone is a widely sold half-measure. The same is true in the opposite direction: training with an inadequate protein intake produces a smaller result than it should.
Older vegetarians and vegans face the tightest version of this problem, because a higher per-meal threshold meets the generally lower leucine content of plant proteins. Reaching 35 to 40 grams of plant protein in a meal takes planning rather than luck. It is achievable, and this is the group for whom a protein powder used as a convenience rather than as a supplement makes the most sense.
One severe exception applies to the whole of this section. Advanced kidney disease without dialysis is a condition in which protein is restricted deliberately, and older adults are disproportionately likely to have it. The recommendations above assume normal kidney function, and where that assumption does not hold the intake is a matter for the treating clinician rather than for a position paper read at second hand.
The kidney question, answered honestly
The claim that high protein damages the kidneys is the most persistent piece of nutritional folklore in this area, and it deserves a careful answer rather than a dismissive one, because it originated in something real. Protein restriction is a genuine clinical tool in chronic kidney disease. Reducing protein intake reduces the filtration workload on kidneys that are already compromised, and that is established practice. The error was extrapolating from damaged kidneys to healthy ones.
For healthy kidneys, the relevant evidence is a systematic review and meta-analysis by Devries and colleagues, which examined changes in kidney function in healthy adults consuming higher compared with lower or normal protein diets. It did not find differences in kidney function attributable to the higher intakes. That is the correct evidentiary basis for the statement that high protein does not damage healthy kidneys, and it is a stronger basis than the absence of case reports.
The honest caveats are three. Established kidney disease changes the calculation entirely, and anybody with diagnosed kidney disease should treat protein intake as a decision for their nephrologist rather than a calculator. A history of kidney stones, gout or liver disease is a reason to have the conversation before making a large change. And higher protein intakes increase urea production and therefore water turnover, so drinking to thirst rather than to habit is sensible at the top of the range.
It is also worth saying what the evidence does not establish, which is that higher protein is protective of kidney function. The finding is an absence of harm in healthy people, not a benefit. Absence of harm is what the question asked for, and overstating it into a benefit would repeat exactly the error that created the myth.
What the top of the range does not support
Above roughly 2.2 grams per kilogram of body weight, the evidence for additional benefit to lean mass runs out. The meta-analytic plateau is the clearest statement of that: beyond it, the pooled data stopped showing further gains, and the confidence interval that extends to 2.2 is a description of uncertainty rather than an invitation to keep climbing. The reasonable summary is that very high intakes have not been shown to be harmful in healthy people and have not been shown to be useful either, which is a less satisfying conclusion than either camp wants.
There are real costs to pushing past the evidenced range, and they are practical rather than medical. Protein is the most satiating and the most expensive macronutrient, so a very high target displaces carbohydrate and fat from a fixed calorie budget. In a deficit that displacement can compromise training quality by leaving too little carbohydrate, and it can push fat below the floor that matters for hormonal function and fat-soluble vitamin absorption. Those trade-offs are covered in the macros guide.
The other cost is attention. Someone eating 2.8 grams per kilogram is spending a meaningful amount of daily effort on the last portion of a curve that flattened long ago, and that attention is almost always better spent on total energy, on training consistency or on sleep. The list of things that matter more than the difference between 1.8 and 2.6 grams per kilogram is long, and everything on it is duller.
One genuine exception deserves noting. Very lean people in aggressive deficits, and people in the final weeks of physique competition preparation, operate under conditions the general evidence was not collected in, and the protein intakes used in that context sit above the general range for defensible reasons. That is a narrow case with its own literature, and it is not a template for anybody else.
Frequently asked questions
Is 0.8 g per kilogram enough protein?
It is enough to prevent deficiency, which is the question the figure was designed to answer, and it is not the amount associated with the best outcomes for muscle retention, training adaptation or healthy ageing. The 0.8 gram Recommended Dietary Allowance comes from nitrogen balance studies and marks the point below which healthy adults begin losing nitrogen. If you train with weights, are dieting, or are over 65, every relevant body of evidence points somewhere above it, and for older adults in particular the recommended intake sits clearly higher than the RDA rather than below it.
Does protein have to be spread evenly across the day?
Roughly, but the effect is second-order and total daily intake matters far more. Controlled work feeding identical daily totals in different patterns found that moderate doses every few hours outperformed both very small frequent doses and very large infrequent ones, and practical guidance lands near 0.4 grams per kilogram of body weight per meal across at least four meals. The realistic advice is to make sure three or four eating occasions each contain a proper dose rather than to obsess over exact timing. Breakfast is where most people fall short.
Is high protein bad for your kidneys?
Not in people with healthy kidneys, on the available evidence. A systematic review and meta-analysis comparing higher protein diets with lower or normal protein diets in healthy adults did not find differences in kidney function. The myth originated in a real clinical practice, because protein restriction genuinely helps kidneys that are already damaged, and that finding was wrongly extrapolated to healthy people. Established kidney disease changes the picture entirely and makes protein intake a matter for a nephrologist, and a history of stones, gout or liver disease is worth a conversation before any large change.
Do older adults need more or less protein?
More per kilogram of body weight, not less, because ageing muscle produces a smaller synthetic response to the same dose of protein. This is called anabolic resistance, and it means an identical meal accomplishes less than it would in a younger person. The PROT-AGE position paper recommends at least 1.0 to 1.2 grams per kilogram a day for healthy older adults and 1.2 to 1.5 during acute or chronic illness, both above the general adult RDA of 0.8. Protein alone will not prevent sarcopenia; it needs a resistance training stimulus to act on.
Can you eat too much protein in one meal?
You can eat more than the muscle protein synthesis response can use, but the surplus is not wasted in any harmful sense; it is used for other purposes or oxidised for energy. Practical guidance from the review literature lands near 0.4 grams per kilogram of body weight per meal as a dose that reliably produces a full response, so an 80 kilogram adult is well served by roughly 32 grams. Eating 60 grams in one sitting is not a problem, it simply does not produce double the response. Distributing across meals is a refinement, not a rescue.
Put it into practice
Run your own numbers through the protein calculator, the macros calculator and the lean body mass calculator. Related reading: Setting your macros, How many calories to eat and Track without DEXA.
Sources
- Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington DC: National Academies Press, 2005 - protein RDA 0.8 g/kg/day for adults. doi.org/10.17226/10490
- FAO/WHO/UNU Expert Consultation. Protein and amino acid requirements in human nutrition. WHO Technical Report Series 935. Geneva, 2007 - safe level of intake 0.83 g/kg/day. iris.who.int/handle/10665/43411
- EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific opinion on dietary reference values for protein. EFSA Journal 2012;10:2557. doi.org/10.2903/j.efsa.2012.2557
- Morton RW, Murphy KT, McKellar SR, 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;52:376-84. doi.org/10.1136/bjsports-2017-097608
- Helms ER, Zinn C, Rowlands DS, Brown SR. 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;24:127-38. doi.org/10.1123/ijsnem.2013-0054
- Areta JL, Burke LM, Ross ML, et al. Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. J Physiol 2013;591:2319-31. doi.org/10.1113/jphysiol.2012.244897
- 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. doi.org/10.1186/s12970-018-0215-1
- Bauer J, Biolo G, Cederholm T, 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;14:542-59. doi.org/10.1016/j.jamda.2013.05.021
- Devries MC, Sithamparapillai A, Brimble KS, Banfield L, Morton RW, Phillips SM. 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;148:1760-75. doi.org/10.1093/jn/nxy197
Cite this page
Quoting a figure from here in an article, a report or a piece of coursework? Use whichever of these your style guide asks for.
- APA
- Campbell, R. (2026). How much protein do you actually need?. Body Stats. https://bodystats.co/app/guides/how-much-protein-do-you-need
- Plain text
- “How much protein do you actually need?”, Body Stats, last updated 13 September 2026, https://bodystats.co/app/guides/how-much-protein-do-you-need
This guide is informational and educational, not medical advice. Formula details live on the methodology page; see also the medical disclaimer.
Last updated . Written by Rick Campbell; not medically reviewed. See review status.