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Protein + lifting
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In one pass How much protein does someone who lifts need each day? Not this — More protein always means more muscle — Hypertrophy returns plateau around 1.6 g/kg/day; extra protein past that adds less and less. 0.8 g/kg is the deficiency floor, not the training dose.
Educational content, not medical advice — consult a clinician.
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Chapter 1
How much protein per day
How much protein does someone who lifts need each day? The most reliable answer is about 1.6 g per kilogram of body weight, and up to 2.2 g for people who want to squeeze out every bit of muscle gain. The range comes from pooling dozens of strength-training trials: gains level off around 1.6 g, and eating more adds very little.
On the plate: a 70 kg person eating 1.8 g per kilogram needs about 126 g of protein a day. Split across 4 meals, that is 30–35 g each. Common foods, roughly:
Chicken breast, 100 g cooked: about 28 g of proteinOne egg: about 6–7 gA cup of milk (240 ml): about 8 gGreek yogurt, 150 g: about 15 gTofu, 100 g: about 8 g (firm) or 5 g (soft)
The official recommendation for ordinary adults is only 0.8 g per kilogram, far lower. The two numbers answer different questions.
On the plate: a 70 kg person eating 1.8 g per kilogram needs about 126 g of protein a day. Split across 4 meals, that is 30–35 g each. Common foods, roughly:
Chicken breast, 100 g cooked: about 28 g of proteinOne egg: about 6–7 gA cup of milk (240 ml): about 8 gGreek yogurt, 150 g: about 15 gTofu, 100 g: about 8 g (firm) or 5 g (soft)
The official recommendation for ordinary adults is only 0.8 g per kilogram, far lower. The two numbers answer different questions.
Evidence · Where 1.6 comes from, what 0.8 is for
Where 1.6 and 2.2 come fromThe range of 1.6–2.2 g per kilogram a day comes from the Morton 2018 : 49 and 1863 healthy adults doing strength training, each program lasting 6 weeks or more. Muscle gains largely topped out once daily protein reached about 1.62 g per kilogram. That turning point is not pinned down precisely, though. Its 95% (the range the true value most likely falls in) runs from 1.03 to 2.20, so the authors say about 2.2 g is the safer target for people who want to maximize gains. The same paper found that the timing of supplements, the size of the post-workout serving and the protein source had little or no effect on results after several weeks.
What 0.8 is for
The official recommendation for ordinary adults, the Recommended Dietary Allowance (), is 0.8 g per kilogram. It is the floor that keeps you from running short of protein, not the amount that grows muscle best. For someone who trains seriously, it is on the low side.
The difference is not how much counts as enough. It is enough for what.
The 0.8 figure came from nitrogen-balance experiments. Protein contains nitrogen, and when the body breaks protein down, that nitrogen becomes urea and leaves in the urine. Researchers fed people different amounts of protein, measured how much nitrogen went in and how much came out, and looked for the point where what comes in just covers what goes out. At that point the protein in your body is no longer being lost: you are not shedding muscle, and you are not heading toward a deficiency.
But not losing and growing are two different goals. Someone who lifts wants a stretch of each day when building outruns breakdown, and that surplus has to add up day after day. If the raw material only covers break-even, the small damage training does to muscle fibers can at best be repaired. There is nothing left over to make the fibers thicker.
This difference explains two more things
Why eating more eventually stops helping. Going from not enough raw material to enough makes a big difference. Going from enough to more leaves the extra with no job to do, so it is broken down and burned as fuel.Why older adults need more, not less. The 0.8 line was drawn so that ordinary adults would not get sick. Older muscle already responds more weakly to the same serving of protein, so eating at the floor makes even breaking even a struggle.
So the next time you see a protein recommendation, first ask whether it was set so you would not get sick or set so muscle would grow. Those two lines have never sat at the same height.
Chapter 2
Spreading protein across meals
Once you eat enough for the day, how you split it across meals also matters. A meal with protein switches muscle building on for a few hours, and then it falls back. So the same daily total, split into 3–4 meals of 0.3–0.5 g per kilogram of body weight each, switches it on several times a day. Packed into one or two big meals, it leaves most of the day empty.
The switch is flipped by one essential amino acid, leucine. A meal needs enough protein for blood leucine to clear a threshold before muscle protein synthesis (MPS) really gets going. Past a certain size, though, a bigger meal no longer raises synthesis much over the next few hours.
An example: a 70 kg person eating about 130 g of protein a day. Two meals of 65 g, morning and evening, do less than four meals of 32 g at breakfast, lunch, dinner and before bed. Keep the size of this in mind: the benefit of splitting shows up mainly in lab studies that measure synthesis over a few hours. For how much muscle you have gained months later, it matters far less than the daily total. On training days you can add a small meal after the session, for 5–6 meals, and go back to 4 on rest days, keeping the total near 1.8 g per kilogram.
The switch is flipped by one essential amino acid, leucine. A meal needs enough protein for blood leucine to clear a threshold before muscle protein synthesis (MPS) really gets going. Past a certain size, though, a bigger meal no longer raises synthesis much over the next few hours.
An example: a 70 kg person eating about 130 g of protein a day. Two meals of 65 g, morning and evening, do less than four meals of 32 g at breakfast, lunch, dinner and before bed. Keep the size of this in mind: the benefit of splitting shows up mainly in lab studies that measure synthesis over a few hours. For how much muscle you have gained months later, it matters far less than the daily total. On training days you can add a small meal after the session, for 5–6 meals, and go back to 4 on rest days, keeping the total near 1.8 g per kilogram.
Mechanism · How leucine switches synthesis on
Where the evidence for splitting meals comes fromMostly from lab studies that measure synthesis over a few hours to half a day. Areta 2013 gave 24 trained young men the same 80 g of whey protein over the 12 hours after a workout, split in different ways: 8 servings of 10 g, 4 of 20 g, or 2 of 40 g. All three raised muscle-fiber protein synthesis well above rest, and 4 servings of 20 g raised it most. The study measured the rate of synthesis over 12 hours, not muscle mass weeks later.
The switch is a metaphor for a concrete chain
Saying a meal switches on muscle building is easy to remember, but it hides three questions you can actually work out. What is the switch? Who presses it? And why does pressing harder stop doing anything past a point?
1. Muscle cells have a sensor that counts leucine
You eat a piece of chicken breast. The stomach and small intestine break the protein into single amino acids, which enter the blood and are taken up by muscle cells. Inside those cells sits a small group of proteins whose job is to watch the level of leucine. When leucine rises, they grab it, and their shape changes.
Why leucine as the signal? Because it is an essential amino acid: the body cannot make it, so it can only come from food. A rise in blood leucine almost always means you just ate something with protein in it. It is a messenger that does not give false alarms.
2. When the sensor lets go, is released
Those sensor proteins are not idle the rest of the time. They hold on to something else: a complex whose job is to keep the brake on mTORC1. When leucine rises, the sensors let go of that complex and grab leucine instead, and the brake comes off.
mTORC1 is the cell's master switch for whether to start building. Once the brake is off, it is pulled to the surface of the lysosome inside the cell and turned on. It then adds phosphate groups to several proteins that start translation. In plain terms, it moves the ribosomes from standby to work, and they begin linking amino acids from the blood, one by one, into the protein chains of the muscle fiber. That is the moment muscle protein synthesis (MPS) actually begins.
So the switch is a concrete chain: leucine level rises → the sensor releases the brake → mTORC1 turns on → ribosomes start work. There is a threshold because releasing the brake takes enough leucine arriving at once. A slow trickle cannot loosen it.
This also clears up an expensive misunderstanding: leucine is the starting pistol, not the bullet. It calls for work to begin, but what gets built into muscle is the full set of essential amino acids. Taking only leucine or branched-chain amino acids () without a full serving of protein rings the start bell without delivering the bricks. The bell rings, and the building site stays idle.
3. Why a bigger meal stops raising synthesis
It is not as simple as the body cannot absorb it. There are at least two reasons.
Reason one: two taxes are taken before protein reaches your muscle. Amino acids from digested protein are absorbed in the small intestine, and their first stop is not the blood but the gut wall itself. Gut-wall cells renew very quickly and keep some for their own use. What is left travels through the portal vein to the liver first, and the liver takes another share to make blood proteins, for other uses, or to burn as fuel. Only part of what you ate reaches the muscles in your legs and back. That is why how much you ate and how much your muscle received are never the same number.
Reason two: once work starts, the assembly line has a speed limit. Even with the switch fully on, ribosomes can only link amino acids so fast. Extra amino acids in the blood do not wait in line. They are broken down and burned as fuel, or turned into urea and passed in the urine. And when blood amino acids stay high for a long time, synthesis itself falls back: the muscle acts full, stops responding to the signal, and does not keep building.
Note that these are measurements over a few hours. Whether one large protein meal buys extra synthesis over half a day or longer is still debated. So the takeaway is there is no need to chase one huge meal, not every extra bite is wasted.
4. What this chain explains
Why plant protein needs to be eaten in larger amounts: it is not unusable. Gram for gram, it carries a thinner mix of leucine and the other essential amino acids. With less powder in the starting pistol, you need to load more before it fires.Why older adults need more per meal: several links in this chain weaken with age, so the same leucine level releases less of the brake. The answer is not a vague eat more over the day but make each meal bigger, so it can clear the higher threshold.
The day's total decides whether you have raw material; the amount at each meal decides whether that material gets put to work.
Myth · The 30-minute post-workout window
Having to take protein right after training is one of the most widespread ideas in gyms. The Aragon & Schoenfeld 2013 review went through the existing research and concluded that there is no window you must catch within 30 minutes of training. Its practical advice is that pre- and post-exercise meals should not be separated by more than about 3–4 hours, and that your total protein for the day matters much more than the exact time you eat it. The Morton 2018 also found that supplement timing had little or no effect on muscle gained over several weeks.In daily life: a normal meal with protein 1–3 hours before training and another 1–2 hours after already covers the time around your workout. So there is no need to squeeze in a protein shake before training; an ordinary meal with meat, eggs, dairy or soy foods is enough. Nor do you need to rush protein down within 30 minutes of finishing.
After training, muscle building stays raised for a day or two. That is an effect of the training itself, not a feeding window to catch by the minute. Hypertrophy mechanisms goes further into how training makes muscle grow.
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Chapter 3
Protein quality and sources
Protein is not only about quantity; quality counts too. Today's yardstick is the Digestible Indispensable Amino Acid Score (DIAAS). It measures how much of a protein the body actually absorbs, and how completely it supplies the amino acids needed to build muscle. It is more accurate than the older PDCAAS.
By this measure, animal proteins generally rank higher, with milk at the top. Plant proteins sit a step lower: soy is the best of them, and wheat gluten comes last. The difference is the mix. Animal protein carries leucine and the other essential amino acids in fuller proportions, so a single meal more easily pushes the muscle-building switch past its threshold.
That does not make plant protein useless. You need to eat a bit more of it and combine types that fill each other's gaps: legumes are short on methionine, grains are short on lysine, and beans with rice or wheat cover each other. Vegans can build muscle too, with soy, peas and other legumes paired with whole grains, and a soy or pea protein powder when needed to reach the daily total.
By this measure, animal proteins generally rank higher, with milk at the top. Plant proteins sit a step lower: soy is the best of them, and wheat gluten comes last. The difference is the mix. Animal protein carries leucine and the other essential amino acids in fuller proportions, so a single meal more easily pushes the muscle-building switch past its threshold.
That does not make plant protein useless. You need to eat a bit more of it and combine types that fill each other's gaps: legumes are short on methionine, grains are short on lysine, and beans with rice or wheat cover each other. Vegans can build muscle too, with soy, peas and other legumes paired with whole grains, and a soy or pea protein powder when needed to reach the daily total.
Numbers · How to read the DIAAS score table
Scores for common proteinsDifferent studies measure somewhat different scores; these are common reference values. Animal proteins generally rank at the top, most around 1.1, with milk highest at about 1.18. Plant proteins sit a step lower. Soy is the best of them at about 0.91, tofu 0.87, pea protein 0.65, and wheat gluten last at only 0.40.
How the score is measured
It is not measured in a test tube. Researchers feed a protein, collect what has not been absorbed at the end of the small intestine (the ileum), and work out, for each essential amino acid, the share that actually entered the blood. The older PDCAAS was measured in stool. But food residue that reaches the large intestine is reworked by bacteria, so the measured absorption comes out too high. That is why DIAAS is more accurate.
Why the score is the shortest stave
Once the absorbed share of each essential amino acid is known, DIAAS does not average them. It takes the lowest one as the protein's score.
The reason is simple: building a muscle protein chain needs a fixed set of amino acids in fixed proportions. If one is missing, the chain stops there, and a surplus of the others cannot make up for it. This is the barrel effect: a wooden barrel holds only as much water as its shortest stave allows.
That makes the score table easy to read:
Wheat gluten ranks last not because it is low in protein (gluten is actually very high in protein) but because it is very short on lysine. Its short stave is especially short.Legumes are short on methionine and grains are short on lysine, and these are different staves. In a meal of beans with rice or wheat, each one's long stave covers the other's short one, so the combined meal has a much less severe weak point.Animal proteins score high for two reasons: they digest easily, and their amino acid mix is closer to that of human muscle. Meat, after all, is another animal's muscle.
How to use it
The score is not for ranking foods. It tells you where a meal's weak point is. People who eat animal protein all day barely need to think about it. For vegetarians and people who eat mostly plant protein, it works as a what-to-pair-with-what guide: beans with grains, peas with rice, combined within the same meal, and the weak point is covered. This is also why plant protein needs to be eaten in larger amounts. Plant protein is not bad; it takes more and pairing to lift that short stave.
What the evidence says about vegan muscle gain
Hevia-Larraín 2021 compared 19 long-term vegan and 19 omnivorous young men. Groups were set by each man's usual diet, not by randomization. Both groups did supervised strength training twice a week for 12 weeks, with protein topped up to 1.6 g per kilogram a day: soy protein isolate for the vegans, whey for the omnivores. Both groups gained about 1.2 kg of leg lean mass, with no differences in muscle-fiber growth or gains in maximum leg-press weight. The study was small and not randomized, so it shows that vegans can build muscle normally when total protein is high enough; it does not show that the two proteins are fully equivalent.
Chapter 4
Older adults need more
With age, you need more protein, not less. The body has not become better at building muscle; it has become duller. The same serving of protein produces a clearly weaker building response in older muscle. This is called anabolic resistance.
At the level of a single meal: pooled estimates suggest that pushing one meal's muscle building to its peak takes about 0.24 g of protein per kilogram of body weight in young adults, but around 0.40 g in older adults. So older people should have a proper serving of protein at every meal, rather than relying on one meal a day to cover it.
Preventing sarcopenia (the loss of muscle that speeds up with age) therefore does not mean eating lightly. It means the opposite: a good serving of protein at every meal, plus strength training 2–3 times a week. Even in people in their nineties, regular strength training still clearly raises strength.
At the level of a single meal: pooled estimates suggest that pushing one meal's muscle building to its peak takes about 0.24 g of protein per kilogram of body weight in young adults, but around 0.40 g in older adults. So older people should have a proper serving of protein at every meal, rather than relying on one meal a day to cover it.
Preventing sarcopenia (the loss of muscle that speeds up with age) therefore does not mean eating lightly. It means the opposite: a good serving of protein at every meal, plus strength training 2–3 times a week. Even in people in their nineties, regular strength training still clearly raises strength.
Clinical · How much older adults need, and why
Recommended amounts for older adultsThe European PROT-AGE consensus (2013) gives daily protein for people over 65: 1.0–1.2 g per kilogram if healthy, at least 1.2 g for those who exercise regularly, and 1.2–1.5 g with an acute or chronic illness (up to 2.0 g with severe illness or clear malnutrition). People with severe kidney disease who are not on dialysis are the exception; their protein intake should be set by their doctor.
All of these sit above the 0.8 for ordinary adults and below the roughly 1.6 used by young people who lift. For older adults, the first goal is not to slide: without active effort, muscle is lost year after year by default.
The trial in the very old
Fiatarone 1994 ran a randomized trial in frail, very old nursing-home residents, comparing high-intensity strength training, a nutritional supplement, both, and neither. Those who trained more than doubled their strength; those who did not train barely changed. The supplement had no effect on any of the main outcomes. The change in thigh-muscle cross-section also did not differ significantly between trainers and non-trainers. What the trial shows is that muscle in people around ninety still responds to the training signal. It did not show that extra nutrition added anything on its own.
Which links weaken in older muscle
The muscle-building chain (leucine level rises → the sensor inside the cell releases the brake → turns on → ribosomes start work) is not broken in older adults. Several links have loosened a little, and together they add up to the same serving of protein, a noticeably weaker response. Researchers point to three main causes:
Delivery falls short: after a meal, blood flow to muscle rises less than in youth, so blood carrying amino acids and insulin does not reach the muscle fibers as well, and the local signal is weaker.More is held back on the way: before amino acids reach muscle, the gut wall and liver take a share. Older adults may lose a larger share there, so less of the same serving reaches muscle.The signal itself dulls: even when leucine levels are high enough, the cell's sensing machinery does not respond as sharply as in youth, and the same level releases less of the brake.
So the answer is not simply eating more
All three point to the same practice: make each meal bigger rather than spreading the total thin. The threshold has risen, so it takes a larger serving to clear it. That is why, for older adults, how much at each meal matters more than how much in a day.
Strength training does one more job here: for a while after a session, muscle becomes more sensitive to amino acids again. In other words, training partly offsets the dulling. That is why a serious nutrition plan for older adults almost never covers eating without also covering training.
References · 6
- 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. 49 RCTs, 1,863 participants, resistance training of 6 weeks or more. Protein supplementation added 2.49 kg to 1RM and 0.30 kg to fat-free mass; the effect fell with age and was larger in trained people. Break point for FFM gains at 1.62 g/kg/day (95% CI 1.03-2.20; 42 study arms, 723 participants; the biphasic model was not statistically significant, p = 0.079); given the CI, the authors say ~2.2 g/kg/day may be prudent for those maximising gains; timing, post-exercise dose and source play a minor if any role; they cite per-dose MPS break points of 0.24 (younger) and 0.40 g/kg (older). One author reports grant support from the US National Dairy Council (abstract and full text, PMC5867436). 10.1136/bjsports-2017-097608
- Phillips, S. M. (2016). The impact of protein quality on the promotion of resistance exercise-induced changes in muscle mass. Nutrition & Metabolism, 13, 64. Per-meal 0.3-0.5 g/kg distribution + DIAAS-quality dominates over total intake alone. 10.1186/s12986-016-0124-8
- Areta, J. L., Burke, L. M., Ross, M. L., Camera, D. M., West, D. W. D., Broad, E. M., et al. (2013). Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. Journal of Physiology, 591(9), 2319-2331. With 80 g protein over 12 h, 4×20 g every 3 h maximized myofibrillar protein synthesis vs 8×10 g/1.5 h and 2×40 g/6 h. 24 healthy trained men, 3 groups of 8, each given 80 g whey over 12 h after resistance exercise (8 x 10 g every 1.5 h, 4 x 20 g every 3 h, 2 x 40 g every 6 h). All raised myofibrillar protein synthesis 88-148% above rest; the 4 x 20 g pattern exceeded the other two by 31-48% (abstract, PMID 23459753). 10.1113/jphysiol.2012.244897
- Hevia-Larraín, V., Gualano, B., Longobardi, I., Gil, S., Fernandes, A. L., Costa, L. A. R., et al. (2021). High-protein plant-based diet versus a protein-matched omnivorous diet to support resistance training adaptations: a comparison between habitual vegans and omnivores. Sports Medicine, 51(6), 1317-1330. Not randomised - groups were set by habitual diet: 19 vegan and 19 omnivorous young men, 12 weeks of supervised twice-weekly resistance training, protein topped up to 1.6 g/kg/day with soy isolate (vegans) or whey (omnivores). Both groups gained leg lean mass (1.2 vs 1.2 kg), muscle and fibre cross-sectional area and leg-press 1RM, with no between-group differences. Retrospectively registered (abstract, PMID 33599941). 10.1007/s40279-021-01434-9
- Fiatarone, M. A., O'Neill, E. F., Ryan, N. D., Clements, K. M., Solares, G. R., Nelson, M. E., et al. (1994). Exercise training and nutritional supplementation for physical frailty in very elderly people. New England Journal of Medicine, 330(25), 1769-1775. 100 frail nursing-home residents (63 women, 37 men; mean age 87, range 72-98), 10 weeks, 94% completed. Strength rose 113% with resistance training vs 3% without; gait velocity +11.8% vs -1.0%; stair-climbing power +28.4% vs +3.6%; thigh-muscle area +2.7% vs -1.8% (P = 0.11, not significant). The multi-nutrient supplement had no effect on any primary outcome (abstract, PMID 8190152). 10.1056/NEJM199406233302501
- Bauer, J., Biolo, G., Cederholm, T., Cesari, M., Cruz-Jentoft, A. J., Morley, J. E., et al. (2013). Evidence-based recommendations for optimal dietary protein intake in older people: PROT-AGE Study Group. JAMDA, 14(8), 542-559. 10.1016/j.jamda.2013.05.021