How Much Protein Do You Really Need? The Science, Settled

Updated on April 16, 2026

The supplement industry would very much like you to believe you are perpetually protein-deficient. Tubs of whey, collagen shots, protein-fortified pasta — all of it rests on a single anxious premise: that you are not getting enough. The evidence, when you actually read it, tells a more complicated and considerably cheaper story.

Let's work through what the research actually says, group by group, and separate the numbers that matter from the ones someone is trying to sell you.

The Baseline: What "Enough" Even Means

The current Recommended Dietary Allowance (RDA) for protein in healthy adults is 0.8 grams per kilogram of body weight per day. A 70 kg adult, then, needs roughly 56 grams. That is a minimum floor — the amount required to prevent deficiency in 97.5% of sedentary adults — not an optimal target. This distinction gets blurred constantly, including by researchers who should know better.

The RDA is derived from nitrogen balance studies, which are themselves imperfect. Protein contains nitrogen; if you excrete more than you consume, you're in negative balance and presumably losing muscle tissue. These studies have methodological weaknesses — they tend to underestimate actual needs because short-term adaptation can mask longer-term insufficiency. A 2017 meta-analysis in the British Journal of Sports Medicine put the number for muscle preservation closer to 1.62 g/kg/day for people doing resistance training, but that's a ceiling for muscle gain, not a floor for normal function.

The honest answer for sedentary adults: 0.8 g/kg is likely fine. Probably even 1.0 g/kg to give yourself comfortable headroom, especially if your total calorie intake is modest.

Athletes and People Who Train Seriously

Here the picture sharpens considerably. The International Society of Sports Nutrition's 2017 position stand reviewed the literature and landed on 1.4–2.0 g/kg/day for exercising individuals, with 2.0 g/kg being appropriate for those trying to gain muscle while in a calorie surplus, or preserve it while losing fat.

What's interesting is the ceiling. Study after study finds essentially no benefit to going above 2.2 g/kg for muscle protein synthesis. A 2018 randomised trial published in the American Journal of Clinical Nutrition gave trained young men either 1.2 or 2.4 g/kg/day and found no additional lean mass gain in the higher group over 12 weeks. The extra protein was simply oxidised for energy — expensive firewood.

Endurance athletes occupy slightly different territory. Their per-kg needs are lower than strength athletes — roughly 1.2–1.6 g/kg/day — but they tend to neglect protein relative to carbohydrate, sometimes to the detriment of soft tissue recovery. If you're running 60+ km per week, hitting 1.4 g/kg is sensible. You do not need a protein shake after every easy run.

Timing matters somewhat, but less than marketing suggests. Spreading intake across three to four meals gives muscles multiple stimulation windows, and there's reasonable evidence for consuming 20–40g within a couple of hours of training. But the "anabolic window" — the idea that you must consume protein within 30 minutes or the workout was wasted — is largely fiction. A 2013 meta-analysis by Schoenfeld and Aragon found total daily intake matters far more than timing precision.

People Trying to Lose Weight

This is where higher protein intakes have the clearest practical case, and where the research is most consistent.

Protein is the most satiating macronutrient. Studies measuring ad libitum calorie intake reliably show that people eat less when protein is higher. The mechanisms include slower gastric emptying, increased peptide YY and GLP-1 secretion, and a higher thermic effect — protein costs about 20–30% of its own calories just to digest, compared to 5–10% for carbohydrate and 0–3% for fat.

More important for dieters: muscle preservation during a deficit requires higher protein than maintenance. When you're eating below your needs, the body becomes less efficient at using dietary protein for muscle repair, and more of it gets redirected to gluconeogenesis (making glucose for fuel). The practical recommendation from most sports nutrition researchers for active dieters is 2.0–2.4 g/kg of bodyweight, or up to 3.1 g/kg of lean mass if you're using a leaner reference point — useful for people with higher body fat percentages.

A 2016 study in the American Journal of Clinical Nutrition gave resistance-trained men in a significant calorie deficit either 1.2 or 2.4 g/kg/day. The high-protein group lost more fat and gained a small amount of lean mass despite the deficit. This kind of body recomposition — losing fat and gaining or maintaining muscle simultaneously — is essentially the dietary holy grail, and the main lever available to achieve it is protein intake.

Older Adults: The Genuinely Underappreciated Case

Sarcopenia — age-related muscle loss — accelerates significantly after 60, and this is where the 0.8 g/kg RDA shows its most obvious limitations. Older muscle tissue is less responsive to protein: it takes a larger dose of leucine (the key amino acid that triggers muscle protein synthesis) to achieve the same anabolic signal that a smaller dose produces in younger adults. This phenomenon is called "anabolic resistance."

The European Society for Clinical Nutrition and Metabolism recommends 1.0–1.2 g/kg/day as a baseline for healthy older adults, rising to 1.2–1.5 g/kg for those with illness or injury. The PROT-AGE study group, which synthesised data across multiple trials, put their recommendation for healthy older adults at 1.0–1.2 g/kg/day minimum, with active older adults needing 1.2–1.6 g/kg.

Per-meal dose matters more in this group than any other. Research suggests older adults need around 35–40g of protein per meal to maximally stimulate muscle protein synthesis, compared to roughly 20–25g in younger adults. The practical implication: distributing protein across meals is especially important for older people, rather than eating most of it at dinner (which is common in Western eating patterns).

None of this requires supplements. A chicken breast, a cup of Greek yoghurt, two eggs, a tin of sardines — these are affordable, accessible sources that would not look out of place in a dietitian's meal plan from any decade.

What the Marketing Gets Wrong

Two specific distortions are worth naming directly.

First: the "gram per pound of bodyweight" shorthand (roughly 2.2 g/kg) that circulates in gym culture has no strong scientific basis as a universal recommendation. It may be appropriate for someone doing serious resistance training in a deficit; it's overkill for a moderately active person trying to eat well. At that level, excess protein simply adds calories you may not need.

Second: the protein quality conversation, while real, gets weaponised to sell specific products. Yes, animal proteins tend to have a higher leucine content and better digestibility than most plant proteins. But a person eating varied whole plant foods — legumes, tofu, tempeh, whole grains — can hit the same essential amino acid targets. Combining plant proteins within a day (not even within a meal) is sufficient. The idea that plant protein is categorically inadequate for muscle building has been directly tested and largely refuted: a 2019 trial in the American Journal of Clinical Nutrition found no significant difference in muscle gain between whey and soy protein groups over 12 weeks of resistance training.

Practical Numbers, Summarised

  • Sedentary adults: 0.8–1.0 g/kg/day. The RDA is adequate; the top of that range gives you reasonable buffer.
  • Recreational exercisers (3–4x/week): 1.2–1.6 g/kg/day. No need to track obsessively; just make sure protein appears at every main meal.
  • Serious athletes (strength or endurance): 1.6–2.0 g/kg/day. Distribution across 3–4 meals matters; timing post-training has marginal benefit.
  • Active dieters (in calorie deficit): 2.0–2.4 g/kg/day. Higher intake offsets the reduced efficiency of protein utilisation in a deficit.
  • Adults over 65: 1.2–1.6 g/kg/day minimum, with attention to dose-per-meal (aim for 35–40g per sitting).

If you want to actually calculate where you land, a nutrition calculator that takes your weight, activity level, and goal into account will get you a personal figure in under a minute — more useful than any generic headline.

A Final Note on Food vs. Supplements

Whole food protein sources bring more than amino acids. Eggs bring choline and fat-soluble vitamins. Fish brings omega-3s and iodine. Legumes bring fibre and resistant starch. Dairy brings calcium and bioavailable phosphorus. Whey protein brings... whey protein. It is convenient and it works, but it is a tool for filling gaps, not a category of food superior to the ones it's extracted from.

The protein question, stripped of commercial noise, resolves to something quite manageable: eat enough of it, spread it through the day, adjust for your activity and life stage. The evidence has been pointing in the same direction for at least two decades. The uncertainty isn't really scientific — it's commercial.