How much protein per day? For most adults who lift, about 1.2 to 1.6 grams per kilogram of body weight covers it. Someone who weighs 70 kg lands at roughly 85 to 110 grams a day. Researchers pooled 49 trials in 1,863 people, and muscle gains stopped growing at about 1.6 g per kg (Meta-analysis). Eating past that point is not dangerous for healthy people. It just stops adding muscle.
Two beliefs get in the way. One says your body can only use 30 grams at a sitting. The other says more is always better. The same evidence answers both.
What Protein Actually Does
Protein in food is a package of amino acids. Your gut takes it apart. Your body puts the pieces back together as new tissue.
Muscle is never finished. Your body builds it up and breaks it down every day of your life. The building side has a name: muscle protein synthesis. Build more than you break down over a few weeks and you gain. Break down more than you build and you lose.
Eating protein pushes the building side up for a few hours. Training makes muscle more responsive to that protein. Neither does much on its own, which is why protein and strength training work as a pair.
Then there is the number on the back of the cereal box. The official 0.8 g per kg figure comes from nitrogen balance studies. Those feed people set amounts and measure what leaves the body. Pooled together, that method puts the average adult’s need near 0.6 to 0.7 g per kg (Systematic review). The public number is rounded up from there to cover almost everyone.
Look at what that figure was built for. It is the amount that keeps most people from running short. Nobody designed it to build muscle. A different question gives you a different number.
How Much Protein Per Day
Plot muscle gain against protein intake and the line climbs, then flattens. Where it flattens is the answer.
Researchers pooled 49 trials in 1,863 healthy adults who lifted weights (Meta-analysis). Adding protein on top of training gained them about 0.3 kg of extra lean mass, the part of body weight that is not fat. Gains stopped climbing once total daily protein passed roughly 1.6 g per kg. The authors are careful with that figure. They call it a practical estimate rather than a hard cutoff, and the true bend may sit higher.
A bigger analysis found the same shape, and the flattening came even earlier. It pooled 105 published trials in 5,402 people (Meta-analysis). Below a daily total of about 1.3 g per kg, each extra bit of protein bought a solid amount of lean mass. Above it, the same extra bought roughly a third as much.
A third review sorted people into intake bands, using only trials where they also lifted (Meta-analysis). It covered 74 trials, with 2,665 people in the muscle analysis. In adults under 65, extra protein only paid off clearly at 1.6 g per kg and above. In adults 65 and over, a smaller benefit turned up in the 1.2 to 1.6 band. The reviewers called that result low quality. Drop a single study and it disappears.
The floor has moved too. A newer method feeds people rising amounts of protein and tracks a tagged amino acid in the breath. In eight healthy young men it put the amount that covers nearly everyone near 1.2 g per kg, about 50% above the official figure (Study). A review of the 16 studies using this method found 14 of them landed above the official number (Scoping review).
None of this is settled. A 2024 government evidence review prints both sets of numbers side by side. It also says the newer method still has to prove itself (Systematic review). The honest summary is that the real floor probably sits above 0.8, and the ceiling for muscle sits near 1.6.
Now the arithmetic for a 70 kg reader. The low end is about 85 grams a day. The top of the useful range is about 110 grams. Someone who does not train can sit near the bottom. Someone lifting hard, or eating less to lose fat, should aim at the top.
The 30-Gram Meal Myth
Belief one says your body can only use about 30 grams of protein at a time. Two separate lines of evidence say otherwise.
Start with what people ended up with. In a 16-week trial, 43 women aged 20 to 44 cut their calories to lose weight (Trial). A coin flip decided their meal pattern. Both groups ate the same amount of protein. One spread it evenly across meals, and the other loaded most of it at dinner. Weight, fat and lean mass came out the same in both groups, as far as the study could measure.
That result holds when you add lifting. Another 16-week trial fed 41 dieting adults 90 grams of protein a day while they trained three times a week (Trial). One group ate 30 grams at each of three meals. The other ate 10, then 20, then 60 at dinner. Both lost about the same fat and kept about the same lean mass. With roughly 20 people per group, the study could only have caught a big timing effect. A small one could still be hiding.
Now the mechanism. Researchers gave 36 young men nothing, 25 grams or 100 grams of tagged milk protein after a workout (Trial). Then they tracked it for 12 hours. Their bodies were still building the 100 gram meal into tissue when that window closed. Over 85% of what the men ate went into body tissue rather than being burned off.
The 30 gram rule also misreads what the older studies measured. Much of that work used leg-only exercise. After a whole-body session, 40 grams of whey built more muscle than 20 grams in 30 trained men (Trial). The researchers think the bigger dose paid off because more muscle had just been worked. They never tested the two workout styles side by side, so that part stays an idea.
Even the researchers who study per-meal amounts reject a fixed ceiling. They suggest about 0.4 grams per kg at each meal, across at least four meals (Review). For a 70 kg reader that is roughly 28 grams a sitting, and more is fine. They also point out where the familiar 20 to 25 gram figure came from: studies of fast-digesting whey drunk on its own.
One honest caveat before you stop thinking about timing. In 26 untrained young men, spreading protein evenly across three meals gained slightly more lean mass than loading dinner (Trial). The gap was small enough that chance could explain it, and a second muscle measure came out level. Treat an even spread as a mild bonus rather than a rule. Your daily total is what moves the needle, and nobody needs to set an alarm.
When More Stops Working
Belief two says more is always better. It deserves a two-sided answer, because the usual reply is scaremongering.
The useless part first. Past the point where the line flattens, extra grams stop adding tissue (Meta-analysis). A 250 gram a day habit for a 70 kg lifter builds nothing that 110 grams missed. All it costs you is money and cooking time.
The supplement trials make the same point from another angle. In those 49 pooled trials, people already ate about 1.4 g per kg before anyone handed them a shake (Meta-analysis). That is most of the way to the flat part, which is why the average benefit was small. Split by experience, trained lifters gained about 1 kg of extra lean mass from supplementing. In untrained beginners the gain was small enough that chance could explain it.
Now the safety half, since people always ask. Researchers pooled 28 studies in 1,358 adults without kidney disease (Meta-analysis). They compared higher-protein diets against lower ones. Kidney filtration shifted the same way in both. A newer pool of 22 trials found filtration rates rose on high-protein diets, which looks like a normal adjustment to a bigger workload (Meta-analysis). The blood markers of kidney damage stayed put. Those trials were mostly short, so the very long term is untested. It is the same pattern as the kidney worry around creatine: a plausible fear that keeps failing its tests.
One boundary matters here. All of that evidence comes from people with healthy kidneys. Kidney guidelines suggest about 0.8 g per kg for people with moderate to advanced chronic kidney disease (Guideline). Those at risk of getting worse are told to stay under 1.3. If that is you, your number comes from your clinician.
So the strongest case against a huge protein habit is plain waste.
Older Muscle Needs More
Age changes the answer. Older muscle responds less to the same meal, so it may need a bigger one.
Researchers pooled lab studies in healthy older men, around 71 years old, and young men around 22 (Study). The building response levelled off near 0.40 grams per kg of body weight per meal in the older group. In the younger men it levelled off near 0.24. Measured against lean body mass instead of total weight, the gap was wider and clearer. Every participant was male, so read this as a signal rather than a settled figure.
Independent reviewers put the age penalty at roughly two thirds more protein per meal (Review). In practice that means about 40 grams a meal for an older adult, against about 20 for a young one. That estimate comes from pooled dosing data, not from a trial that compared the two directly.
The mismatch is awkward. The people most likely to eat toast and tea for breakfast are the ones who need the biggest protein meals. Appetite shrinks with age and cooking gets harder. Breakfast is usually the thinnest meal of the day.
That makes breakfast the easiest place to gain. Adding eggs, Greek yogurt or milk to a bread-and-jam morning can lift an older reader’s daily total more than anything else on the list.
Your Number in Real Food
Grams per kilogram means nothing until it becomes groceries. So here is a full day for a 70 kg reader aiming at about 110 grams, using US government food data.
Two hard-boiled eggs give about 13 grams (USDA data). A 170 gram tub of plain nonfat Greek yogurt adds about 18 (USDA data). A 150 gram cooked chicken breast does the heavy lifting at about 47 grams (USDA data). A cup of cooked lentils brings 18 more (USDA data). Add a cup of whole milk for about 8 (USDA data) and half a cup of black beans for another 8 (USDA data).
That day comes to about 110 grams. It is a normal amount of food, not a bodybuilder’s diet.
Swaps are easy. A 3 oz cooked salmon fillet gives about 19 grams, less than the same weight of chicken because salmon carries more fat and water (USDA data). Half a cup of firm tofu set with calcium sulfate gives about 22 grams (USDA data). The regular version of the same tofu lists less than half that (USDA data), so read the label rather than trusting one number.
Plant or animal protein is the next question, and the gap is smaller than the arguments suggest. One review of 18 trials pooled 16 of them, and both kinds built the same lean mass and scored the same on every strength test (Meta-analysis). It was not a clean tie. Animal protein came out ahead on lean mass as a share of body weight, and in adults under 50. A larger pool of 43 trials also found a small edge for animal protein on muscle mass (Meta-analysis). But soy protein matched milk protein, and strength came out level overall, apart from a lower-body edge in people over 60. Over 6 to 31 months, 18 more trials in 1,893 people found matching lean mass, strength and walking speed (Meta-analysis). Most of those people were postmenopausal women, and the reviewers rated that evidence weak.
The practical read: a varied plant-based diet works if the total gets there. That usually means bigger servings, and more beans, lentils and soy than an omnivore needs.
That leaves powder. In those 49 pooled trials, the type of supplement and the size of the post-workout dose made no difference to lean-mass gains (Meta-analysis). Timing was not tested directly there, but the authors concluded that such details matter little. A 2025 review pooled five trials comparing shakes before training against shakes after it. Lean mass and upper-body strength came out the same either way, on weak evidence (Meta-analysis).
Powder is a convenient way to hit your grams. It helps when you are short and a shake closes the gap. If you already reach your number with food, it only costs you money.
Frequently Asked Questions
How much protein per day if I don’t lift weights?
The official floor of 0.8 g per kg exists to prevent deficiency, not to build anything. Newer breath-tracer measurements suggest the real requirement sits closer to 1.2 g per kg (Scoping review). Around 1.0 to 1.2 g per kg is a reasonable target if you do not train. Above that, the extra seems to pay off mainly when you also lift weights (Meta-analysis).
Can you eat too much protein?
In healthy adults, higher-protein diets have not been shown to harm the kidneys (Meta-analysis). Most of those trials were short, so the very long term is untested. The bigger problem with very high intakes is that they stop adding muscle, so the effort is wasted. People who already have kidney disease are a separate case, and are told to keep protein lower under medical supervision (Guideline).
Is protein powder necessary?
No. In pooled training trials, the type of supplement and the size of the post-workout dose made no difference to muscle gains (Meta-analysis). Powder helps only when it lifts a daily total that is currently short. Whole food that reaches the same number works just as well.
Do you need protein right after a workout?
Probably not. Five trials compared protein before training against protein after it. Lean mass and upper-body strength came out the same either way, though the evidence was rated weak (Meta-analysis). A large meal is still going into tissue more than 12 hours later, so the window looks far wider than the old advice suggested (Trial).
How much protein should someone over 65 eat?
Pooled trials hint at lean-mass gains in adults over 65 at intakes of 1.2 to 1.6 g per kg a day, though that finding is fragile (Meta-analysis). The amount per meal may matter more with age, since older muscle needs a bigger dose to respond fully (Review). Around 40 grams at each main meal is a sensible aim, and breakfast is the usual weak spot.
Key Takeaways
- The gains flatten near 1.6 g per kg. In 49 pooled training trials, protein above roughly 1.6 g per kg a day added no further lean mass. The authors call that a practical estimate (Meta-analysis).
- Returns shrink even earlier. Across 105 pooled trials, each extra bit of protein above 1.3 g per kg bought roughly a third as much lean mass as it did below (Meta-analysis).
- 0.8 g per kg is a floor, not a target. Breath-tracer studies put the requirement closer to 1.2 g per kg, and 14 of 16 landed above the official figure (Scoping review).
- Your daily total beats meal timing. On a matched 90 grams a day, an even split and a dinner-heavy split gave the same result over 16 weeks of dieting and lifting (Trial).
- Very high intakes are mostly waste. In adults with healthy kidneys, kidney filtration shifted the same way on higher-protein and lower-protein diets (Meta-analysis).
- Older adults may need more per meal. The building response levels off near 0.40 grams per kg per meal in older men, against 0.24 in young men (Study).
Eat Enough, Then Stop Counting
Most people are not doing protein wrong. They are just a little short of a number that turns out to be dull and easy to reach from ordinary food.
Work out your own figure. Multiply your weight in kilograms by 1.2 if you mostly sit, and by 1.6 if you lift. If you are over 65, aim at the top of that range and give breakfast the most attention. Then track one normal day, honestly, and see how far off you are. If you land short, one protein-led meal usually closes the gap.
After that you can stop thinking about it. Hit a sensible total and keep training. The grams take care of themselves. This is one of the few nutrition questions where the evidence broadly agrees, and checking your own day costs nothing.
This article is for educational purposes and is not medical advice. Talk to a qualified clinician before changing your health regimen.
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