Is 1.6 Grams of Protein Enough? Lean Mass vs Real Muscle

Cold open

0:03Host 1You heard the trailer — this is the whole story. Welcome to the Hastrup Review of Science — where artificial intelligence reads real science, so you don't have to pretend you understood the paper. Today, one number that gym culture treats as settled, one point six grams of protein per kilogram of body weight a day, and a scientist arguing about his own claim in public.

0:27Host 2The paper is Show me the muscle: how much can protein really add to exercise gains, by Stuart Phillips of McMaster University in Canada, posted as a preprint on SportRxiv and last modified on October sixth. It has not been peer reviewed, it reports no new data, and it is a reply to two critics of a claim Phillips himself made on Instagram. His conclusion is that one point six is enough for people who lift weights, and that the evidence for more is thin.

0:56Host 1Before anything else, since he is defending his own posts, how much should a listener discount this for who wrote it?

1:04Host 2He puts that on the table himself: he made the statements under discussion and co-authored twenty-eight of the studies he cites. He also lists funding paid to his university from dairy and food companies, including Nestlé Health Sciences, FrieslandCampina and Dairy Farmers of Canada, plus speaking fees from supplement makers. Oddly, that funding comes from people who sell protein, and he is arguing people need less of it, so it is not obviously pulling in his favour.

Why this field exists

1:34Host 1Let me back up a step for people who have never weighed their chicken breast. Why is there a whole field arguing about grams of protein per kilogram in the first place?

1:44Host 2In the wider picture, protein requirements were set decades ago by committees using nitrogen balance, which compares the nitrogen you eat with the nitrogen you excrete. That gave the Recommended Dietary Allowance of zero point eight grams per kilogram, meant for ordinary adults rather than people training hard. Strength athletes have long eaten far more than that, and sports science has spent fifty years trying to say how much more actually does anything.

2:11Host 1So for me, at about eighty kilos, what does zero point eight versus one point six look like on a plate?

2:18Host 2Zero point eight is about sixty-four grams a day for you, and one point six is about a hundred and twenty-eight. The higher figures in this debate, two point two, would be about a hundred and seventy-six. Phillips quotes one of his critics calling the gap between the camps about thirty to fifty grams of protein a day.

What was known before

2:37Host 1Where did one point six come from, then? Was it somebody's rule of thumb, or did it fall out of an actual analysis?

2:45Host 2It came from a two thousand eighteen meta-analysis by Morton and colleagues, Phillips among them, which pooled forty-nine trials of protein supplements during resistance training. They fitted what is called a breakpoint, the intake where extra protein stopped adding fat-free mass, and it landed at one point six two. The uncertainty interval around that point ran all the way from one point zero three to two point two zero, and the p-value was zero point zero seven nine, so it was never a sharp estimate.

3:17Host 1That is a really wide range. If the plausible spot was anywhere from about one to two point two, why did one point six become the famous number rather than the top of the range?

3:29Host 2The same paper actually hedged toward the top, saying it may be prudent to recommend about two point two. Phillips now says that sentence was a hedge and he would not write it today. His point is that the lower end, one point zero three, is just as plausible, nobody recommends it, and picking the top of an interval expresses a preference for more protein, not evidence that more works.

3:53Host 1And who are the two critics he is answering, and what exactly do they say?

3:58Host 2One is Aragon, in an editor's cut of his research review, who argues one point six cannot be a ceiling, that one point six to two point two is better supported, and that lean, trained people in a calorie deficit can benefit from more. He accepts one point two to one point six for the general population. The other is Nuckols, in a long web article, who reanalyses the same trials comparing groups within each study and puts the plateau nearer two point zero.

The open question

4:28Host 1So the fight is not really about whether protein matters, it is about whether the curve flattens at one point six or at two. Is that the real open question?

4:38Host 2That is the surface question, yes. Phillips argues there is a deeper one underneath that both sides share: almost every number in the debate is a kilogram of fat-free mass or lean body mass, and that is not the same thing as muscle. So the real question is whether anyone has shown, with a method that measures muscle, that more than one point six builds more of it.

5:03Host 1Hold on, I always assumed lean mass basically meant muscle. What else is counted in it?

What this paper did

5:10Host 2Everything that is not fat or bone: organs, skin, connective tissue, blood, the gut and whatever is in it, and a lot of water. The paper's headline comparison comes from D'Souza and colleagues, who scanned twenty-one young women the same morning with several methods and also measured muscle directly by a technique called D-three creatine dilution. The body scan reported about forty-one point six kilos of lean mass, and it overshot actual muscle by about twenty point one kilos, roughly half.

5:41Host 1What is D-three creatine dilution, in plain words, and why should I trust it more than the scanner?

5:47Host 2You swallow a small dose of creatine tagged with a harmless heavy form of hydrogen, and from how much it is diluted in urine you can estimate the body's creatine pool. Nearly all of that pool sits in skeletal muscle, so it works as a measure of muscle itself. Phillips calls it about as close to muscle as you can get without a whole-body MRI.

6:09Host 1And the scanner here is the DXA one, the low-dose X-ray people get for bone density?

6:15Host 2Yes, dual-energy X-ray absorptiometry, the standard tool in these trials. A second device, the BodPod, which estimates body composition from air displacement, overshot muscle by twenty-two point eight kilos. Those women carried roughly twenty-one and a half kilos of real muscle.

6:32Host 1If the gap were always about twenty kilos, couldn't you just subtract it and carry on?

6:38Host 2No, and that is the important part. The gap varied from person to person, from about thirteen to twenty-seven kilos, and it grew larger as lean mass increased, which matters most in big, lean people, exactly the lifters in this debate. In about thirteen hundred older men from a large cohort called MrOS, muscle by D-three creatine predicted physical performance, falls and mobility problems well, while DXA lean mass barely did.

7:05Host 1Fair, but in a training study you care about change. If someone starts lifting, their liver does not grow, so surely any extra lean mass is muscle?

7:15Host 2That is the reasonable objection, and Phillips says the data do not consistently support it. In one study of the thigh, DXA and MRI agreed well at a single time point, a correlation of zero point eight nine, but for change over ten weeks of light training the correlation fell to zero point four nine. He grants that some of that is noise, since the changes were small.

7:38Host 1What else can move lean mass without any new muscle being built?

7:42Host 2Food and water, quickly. In trained cyclists, forty-eight hours of carbohydrate loading raised DXA lean mass by about two percent, and about three percent with creatine as well, far too fast to be new muscle protein. In a whey trial, a late gain of zero point eight five kilos shrank to zero point two five, no longer significant, once extracellular water was corrected for.

8:07Host 1Can you gain lean mass by eating alone, without going near a gym?

8:11Host 2Apparently yes. Volunteers overfed on a metabolic ward for eight weeks with no training gained about three kilos of DXA lean mass, and Phillips doubts much of it was muscle. In another trial, two thousand calories a day of pure carbohydrate added three point four kilos of fat-free mass over eight weeks of lifting, slightly more than the same calories with a hundred and six grams of protein in them.

8:35Host 1So if I have this right, the ruler everybody uses to measure protein's effect also stretches when you eat pasta or drink water?

8:44Host 2That is his argument, and the authors of the main meta-analyses say similar things in their own papers. One wrote that the extra lean mass from protein may not be muscle, another that fat-free mass changes may be affected by fluid. He applies it to himself too: the one point six figure was fitted to fat-free mass, and his own Instagram caption described a lean mass result as they held their muscle.

Results

9:09Host 1Suppose we accept lean mass at face value anyway, the way the trials do. How big is the protein effect we are arguing over?

9:17Host 2Small. In the two thousand eighteen pooled data, about three months of training alone added one point one kilos of fat-free mass, and supplemental protein added a further zero point three. In the larger two thousand twenty-two update with seventy-four trials, by Nunes and colleagues, each extra gram per kilogram added zero point one four standard deviations of lean mass, with an interval of zero to zero point two seven.

9:43Host 1Standard deviations do not mean much to me. Translated into kilos, what does going from one point six to two point two buy?

9:52Host 2About a fifth of a kilo, around two hundred grams, and that assumes the effect keeps going in a straight line. For comparison, those two days of carbohydrate loading shifted the same measurement by more. And by the D-three creatine work, perhaps half of what lean mass reports is not muscle in the first place.

10:11Host 1Some people would say two hundred grams adds up if you keep at it for years. Does it keep accumulating like that?

10:19Host 2The trial he cites suggests not. In Volek and colleagues, untrained young adults did nine months of supervised lifting, ninety-six sessions, and lean mass in every group rose for three months and then plateaued. The whey group was up three point one kilos at three months, three point five at six and three point three at nine, and its lead over carbohydrate went from zero point seven to only one point zero kilos, not the roughly two it would have reached if the early lead had continued.

10:50Host 1Has anyone actually tested one point six against a much higher intake head to head, rather than inferring it across studies?

10:58Host 2Yes, and that trial carries a lot of weight in the argument. Bagheri and colleagues assigned trained men, about a dozen per group, to one point six or three point two, double the protein, during sixteen weeks of supervised training with a dietitian visit every two weeks. Lean mass rose three point five percent on the lower intake and four percent on the higher, not a significant difference, and strength rose just as much on one point six.

11:26Host 1Is there any study that looked at muscle directly, like fibre size from a biopsy, rather than lean mass?

11:33Host 2A few, and they are underwhelming. In the two thousand eighteen analysis, protein added about three hundred and ten square micrometres of fibre cross-sectional area, but that did not survive when an excluded trial was put back. In a double-blind trial by Reidy, protein nudged lean mass but fibre area and muscle thickness did not differ from placebo, and a pooled strength analysis stopped responding at about one point five.

The protein cost of muscle

12:00Host 1Now the arithmetic part I saw mentioned. How much protein does it physically take to build new muscle?

12:07Host 2He builds an extreme example: an eighty kilo man who adds twenty kilos of pure muscle in a single year, which is more than four times the usual rate, sustained for twelve months. Muscle is mostly water, seventy-five to eighty percent, so if a generous quarter of it is protein, that is five kilos of protein deposited. Spread over three hundred and sixty-five days, it is thirteen point seven grams a day, roughly the protein in two eggs.

12:34Host 1Two eggs a day for a frankly superhuman year? That sounds too small. Surely a lot of what you eat never reaches the muscle?

12:42Host 2Right, so he deliberately piles on penalties. The gut and liver take roughly half of a meal's amino acids before they reach the blood, which doubles it to twenty-seven grams, and if muscle gets only one gram in four, it is fifty-five. Both penalties together, eightfold, give a hundred and ten grams a day, about one point four grams per kilogram on top of maintenance, and he regards that case as unrealistic.

13:08Host 1Why is the eightfold case unrealistic, if those losses really happen?

13:13Host 2Because it follows one meal for five hours and counts every amino acid not yet in muscle as lost, when much of it returns to the body's pool. And muscle mostly rebuilds from its own parts: it turns over one to two percent a day, so this man makes and breaks down about a hundred grams of muscle protein daily, and growth is the small difference between the two. Using the retention rates committees use for requirements, about half, the building cost is twenty-four to twenty-nine grams, about a third of a gram per kilo.

13:45Host 1Does training itself make the body better at recycling that protein?

13:50Host 2That is what his own early work found. After one bout of lifting in fasting volunteers, with nothing coming in from the gut, muscle protein synthesis more than doubled at three hours, breakdown rose about a third, and the net loss expected from fasted muscle was nearly halved. Studies before and after twelve weeks of training found lower protein turnover and a more positive nitrogen balance afterwards.

14:15Host 1So if I add the building cost to the zero point eight baseline, where does my extreme twenty kilo man end up?

14:22Host 2Between one point zero and one point five grams per kilo, and only the eightfold case exceeds one point six. Hard training may raise maintenance itself: nineteen nineties nitrogen balance studies put requirements for bodybuilders at about one point four to one point five, and for trained strength athletes at one point four one. Starting from there, the extreme man needs one point six to two point one, and a realistic new lifter needs one point five to one point six.

14:52Host 1Did those older studies also test what happens when people eat well above that?

14:58Host 2They did. In the novice bodybuilders, two point six two grams did nothing extra for strength or for muscle size on CT scans compared with one point three five. In trained athletes, going from one point four to two point four raised the burning of the amino acid leucine and left whole-body protein synthesis unchanged, which the authors called overload.

Where the extra protein goes

15:22Host 1Then where does the surplus go? If I eat two hundred grams of protein a day, it has to end up somewhere.

15:28Host 2There are two camps. One, from Deutz and Wolfe and later Kim and colleagues, argues there is no practical upper limit to the anabolic response to a meal, with extra protein lowering breakdown and being parked in the gut as a store for later. Trommelen and colleagues gave thirty-six young men zero, twenty-five or a hundred grams of milk protein after lifting, and the hundred gram dose kept muscle building going longer, about forty percent higher than twenty-five grams between four and twelve hours.

15:58Host 1That sounds like a strong result for eating more. Why doesn't Phillips accept it?

16:03Host 2He accepts the short-term findings, and calls them careful studies. His objection is that they cover hours, while muscle is gained over weeks, and nobody has tested whether such a store keeps growing with repeated large intakes. Even in that trial, only about thirteen percent of the hundred grams was in muscle protein after twelve hours, against eighteen percent of the smaller dose.

16:27Host 1And the other camp, what does the body do with protein it does not need?

16:31Host 2It disposes of it: the nitrogen is stripped off and excreted, mostly as urea in mammals, and the carbon skeleton is burned, turned into glucose or, rarely, fat. Human data fit that, with muscle protein synthesis maxing out at twenty grams after exercise while leucine burning rose at twenty and forty grams and urea production at forty. People who habitually eat more gain more after meals but also lose more overnight, so much of the gain is given back.

A word from our sponsor

16:59Host 1We will come back to that. First, a quick word from our sponsor.

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17:15Host 1Is there a breakpoint?

17:17Host 2There is a breakpoint, with an interval from almost nothing to quite a lot. We recommend the top of the interval, out of prudence. Nose-hair trimmers are sold on Amazon at ordinary prices, and the link is in the show notes.

The diet question

17:31Host 1Back to the critics. Aragon's strongest case was lean, trained people dieting hard. What does the evidence say for someone cutting calories?

17:39Host 2The trial often quoted is Longland and colleagues, from Phillips's lab: forty young men on a forty percent calorie deficit, training hard six days a week for four weeks. On two point four grams per kilo they gained one point two kilos of lean mass and lost four point eight of fat; on one point two they gained zero point one and lost three point five. Every performance measure improved equally in both groups.

18:04Host 1That sounds like a clear win for high protein while dieting. What is the catch?

18:09Host 2The two arms were one point two and two point four, so the trial cannot tell you where between them the benefit sits, and one point six lies right in the middle. Aragon also noted those men were untrained and overweight, and Phillips says that is fair but cuts both ways: if they are the wrong people to judge one point two, they are also the wrong people to judge two point four.

18:32Host 1Then has anyone put one point six itself against something higher during a diet?

18:37Host 2Two trials. Pasiakos and colleagues fed people zero point eight, one point six or two point four on a metabolic ward, every meal supplied, for three weeks at a forty percent deficit: fat-free mass was fifty-eight percent of weight lost on zero point eight, thirty percent on one point six, and thirty-six on two point four. The catch is that exercise was light by design.

18:59Host 1And the second one, in actual lifters?

19:01Host 2Thirteen resistance-trained men at thirteen to fourteen percent body fat, mostly competitive athletes, eating sixty percent of their usual calories for two weeks in a double-blind crossover, one point six against two point eight. Fat-free mass, from skinfolds, fell two to three percent on both, with zero point four percentage points in favour of the higher intake, fat loss was almost identical, and strength held slightly better on one point six. The authors rated every body composition difference very likely or almost certainly trivial.

19:34Host 1Was there anything in that trial where the higher protein did make a difference people could feel?

19:40Host 2Yes, and Phillips takes it seriously. Fatigue and stress were greater on one point six, and the one dropout was on that arm, though dietary fat also differed, so even that is muddied. He says feeling better may be a sound reason to eat more protein while dieting hard, just a different reason from building muscle.

19:59Host 1What about the bigger pooled analysis Aragon leaned on for dieters?

20:04Host 2That is Refalo and colleagues, twenty-nine studies in a Bayesian meta-regression, and Phillips calls it considerably stronger than the older review. Its slope was zero point zero seven standard deviations of fat-free mass per extra gram, with over ninety-seven percent probability of being positive, which he accepts. But the authors themselves call it exploratory, diets averaged eight weeks, the outcome was fat-free mass, and it compares across studies.

Lab estimates

20:34Host 1Aragon also pointed to those lab studies that suggested higher requirements. What are they actually measuring?

20:40Host 2They use a method called indicator amino acid oxidation: people sip small hourly portions of free amino acids through one day, and researchers track how much of a marker amino acid gets burned. Where burning stops falling marks where whole-body protein synthesis peaks in the fed state. The studies had seven or eight participants each.

21:00Host 1Whole body meaning muscle plus everything else, so how much of that is muscle?

21:05Host 2About a quarter, twenty-seven percent of whole-body protein synthesis. The gut and liver have first call, and of a twenty gram dose roughly eleven percent ends up in muscle protein over five hours. So the method says nothing about whether muscle grew, and researchers who use it have written that its values should not be misinterpreted as an estimate of protein requirements.

21:27Host 1And if lifters habitually eat a lot of protein before the test, could that push their result up?

21:32Host 2Phillips argues it would. People who usually eat more gain more when fed and lose more when fasting, and the men in one of these studies habitually ate two point three. Measuring only the fed hours in such people will give a high value, and even so, that study's interval started at one point four four.

The reanalysis

21:51Host 1Nuckols did a careful reanalysis, by Phillips's own account. Where do they actually disagree?

21:56Host 2Phillips credits him with showing his working and with being right on two points: the breakpoint was soft, and comparisons across studies can mislead. Nuckols suspects that trained lifters both gain less and eat more protein, which would flatten the curve at the top whatever protein does, a kind of Simpson's paradox. The disagreement is over what replaces the breakpoint.

22:18Host 1What specifically does Phillips think is shaky in that replacement?

22:23Host 2The plateaus come from scatterplots without weights or intervals, with trials included case by case, though often against Nuckols's own interest. His lower bound of one point seven rests on about eight small trials, and the clearest examples include one where two groups on the same forty grams of whey diverged, one gaining one point eight kilos and the other losing zero point one, and one whose seven-man control group volunteered rather than being randomised. Plotting each trial at the midpoint of its two intakes also means a one point two versus two point four trial counts as benefit at one point eight.

22:59Host 1Is there a single test that cuts through those modelling arguments?

23:03Host 2One he points to: a spline from Tagawa and colleagues, which Nuckols included with reservations, predicts about one point three kilos of extra lean mass going from one point six to three point two. That is exactly what the Bagheri trial did, and it found no significant difference. It was missing from the reanalysis only because the dataset predates it.

23:24Host 1So how far apart are they, really, once you strip out the internet framing?

23:29Host 2Closer than people think. Nuckols's best estimate of the plateau is two point zero, inside the original interval, and he writes that you would not be leaving too many gains on the table by sticking with one point six, and that one point two to one point five gives most of the gain. Phillips says the gap is the size of not too many, and all of it is measured in fat-free mass.

23:51Host 1What about the argument that people respond differently, and some individuals might need more?

23:57Host 2People do differ, but the scatter in change scores can be nothing more than measurement error and day-to-day variation. No trial has shown that the people who gain least on one point six would gain more on two point four, and he calls it a hypothesis until a crossover trial tests it. In a survey of natural bodybuilders all eating two point seven to three point three, the top five placers did not differ in protein from the rest.

Women and menopause

24:23Host 1A lot of people listening are women, and I have seen advice that women need more, especially at certain points in the cycle. Does that hold up?

24:31Host 2Phillips examines the position stand on female athletes from the International Society of Sports Nutrition. It recommends one point four to two point two in its abstract, one point eight to two point two in its key recommendations, the upper end in the luteal phase and after menopause, and about twelve percent more in the luteal phase to offset progesterone. He finds no source for the twelve percent, and the stand itself says no studies address protein needs across the menstrual cycle.

24:59Host 1For anyone who needs the reminder, the luteal phase is the second half of the cycle, after ovulation, when progesterone is high?

25:07Host 2Exactly. The stand says progesterone increases amino acid burning and decreases muscle protein synthesis. The first half has some support, from small whole-body studies, including one in five women where the lysine requirement was about eight percent higher in the luteal phase, but none of the cited sources measured muscle protein synthesis across the cycle.

25:28Host 1Did anyone measure it directly, then?

25:30Host 2Yes, with no difference found. Miller and colleagues found essentially identical muscle synthesis rates in fifteen women in either phase, and a study from Phillips's lab measured twelve women over six days in each phase with no effect on synthesis or breakdown. Another of his lab's trials randomised the legs of twenty-four women to train mostly in one phase or the other for three cycles, and the gains in thigh muscle and strength did not differ.

25:56Host 1Do women and men end up with different requirements when they are tested side by side?

26:01Host 2Not in the studies that tested both together. After a twenty kilometre run, the lab estimate was one point six zero in eight men and one point six one in seven women in the luteal phase, a p-value of zero point nine four. With the same training, women and men make similar relative gains in muscle size, and women carry less muscle per kilo of body weight, about thirty-one percent against thirty-eight, so if anything their building cost per kilo is lower.

26:28Host 1And after menopause, when muscle is supposed to drop off quickly?

26:32Host 2The loss is smaller than the wording suggests. In one large American cohort, lean mass went from thirty-eight point five to thirty-eight point two kilos over four years of the transition, a mean loss of zero point seven percent, though about a quarter of women lost four point seven percent or more. Muscle after menopause still responds to training, with strength gains as large as before menopause across a hundred and twenty-six studies, and protein trials there are mixed, with benefits appearing between zero point eight and one point six.

27:03Host 1Does any of this mean older people can get away with the basic zero point eight?

27:09Host 2No, and he is explicit that this is not an argument for the RDA. Older adults need more protein per meal to maximally stimulate muscle, and expert groups recommend at least one point zero to one point two, or more for active people. His position is that one point two to one point six covers older adults, women, and lifters, and that almost no trial evidence exists above one point six in older people at all.

Why it matters

27:35Host 1Step back for me. What is the underlying principle here that goes beyond protein?

27:40Host 2That the thing you measure has to be the thing you care about. If a trial measures fat-free mass, which moves with water, glycogen and food, then a few hundred grams of difference cannot be called muscle. Phillips applies that to his own figure as well: one point six also rests on lean mass, so if you distrust the measure, very little evidence remains that more protein builds more muscle.

28:05Host 1What changes for an ordinary person who lifts a couple of times a week?

28:10Host 2On this reading, aiming for about one point two to one point six grams per kilo covers what the trials support, and the lifting matters far more than the protein above that. His own metaphor is that lifting bakes the cake and protein adds a very thin layer of icing. He also says plainly that nothing here argues against eating more, his objection is to the claim that more is needed.

28:34Host 1And what can we not conclude from it? I do not want to walk away thinking two grams is harmful or useless.

28:41Host 2Right, the paper shows neither. Small null trials cannot rule out a small benefit above one point six, and he says so: absence of a demonstrated benefit is not proof that none exists. And this is a narrative commentary with no systematic search, written by someone defending his own statements, so its choice of studies is its own.

Honest caveats

29:02Host 1Then let's line up the weaknesses, starting with the trials themselves. How solid are they?

29:07Host 2The head-to-head trials of one point six against more had eleven to fourteen people per group and ran two to sixteen weeks, and the closest test with a direct muscle measure had five to eight per arm. Trials that small cannot detect an effect as small as the meta-analyses suggest, which cuts against Phillips's position as much as against his critics.

29:27Host 1How do these trials even know how much protein people ate?

29:31Host 2Mostly they ask them. In most trials free-living participants self-reported their diets, and the contrast between groups was often a supplement on top of uncontrolled eating. Trials where all food was provided, like the metabolic ward study, are the exception, and one trial where a group reported eating more calories yet lost more fat shows how hard self-report is to interpret.

29:53Host 1Anything else in the evidence that both sides are equally stuck with?

29:57Host 2Two more. Breakpoints, splines and meta-regressions all compare group averages across different trials and populations, open to the confounding Nuckols described, and people quote the upper confidence limit as a recommendation while ignoring the lower one. And lab tracer methods describe whole-body metabolism over hours, which cannot show that muscle mass increased over weeks.

30:19Host 1And on the women's side specifically, is the evidence any better?

30:23Host 2Thinner. The stand's daily estimates for women come from a review of four studies and thirty-six women, with nothing pooled, and only the highest estimate reaches two point zero. Phillips agrees with the stand that women have been studied too little, and says the absence of a shown sex difference does not prove there is none.

What to watch next

30:42Host 1So what would settle this, if someone had the money to run the definitive trial?

30:48Host 2He lays out four ingredients in one trial: people already training, moved from one point six to something higher; food provided or rigorously monitored; enough women and men, on the order of fifty per group, that a few unusual responders cannot explain the result; and an outcome that measures muscle, MRI or D-three creatine, with biopsies where possible. He says the result would be informative either way, and that it could refute him.

31:14Host 1Is there a reason that trial does not already exist? It does not sound exotic.

31:19Host 2Mostly cost and practicality. Feeding a hundred trained people for months and putting them through MRI scans is expensive, while adding a shake to a free-living diet and running a DXA scan is cheap. The cheap design is the one the field has been running for decades.

Bottom line

31:36Host 1Pull it together for me. If someone asks me tomorrow whether they need more than one point six, what is the honest answer from this paper?

31:44Host 2On present evidence, one point six grams per kilo appears to be enough for people who lift, whether they are cutting, building or both, and there is no shown reason to set it higher for women or after menopause. The extra lean mass from going higher is at most about two hundred grams, on a measure that is half not muscle. Eating more is fine, but no study measuring muscle has shown that more protein builds more of it.

Sign-off

32:10Host 1That is the deep dive: Show me the muscle: how much can protein really add to exercise gains, by Stuart Phillips of McMaster University, a preprint on SportRxiv. The link is in the show notes.

32:24Host 1Every Friday this same feed carries the roundup episode: five new papers as trailers, and you pick which become deep dives. This has been the Hastrup Review of Science.