The short version
- In a meta-analysis of 49 trials and 1,863 resistance-training participants, gains in fat-free mass stopped increasing above a total protein intake of 1.62 g/kg/day, with a 95% confidence interval of 1.03 to 2.20.
- The same meta-analysis found protein supplementation added an average of 0.30 kg of fat-free mass and 2.49 kg to one-repetition maximum strength over training periods of six weeks or more.
- Pooling 105 studies in 5,402 people, each extra 0.1 g/kg/day of protein was associated with 0.39 kg more lean body mass below a total intake of 1.3 g/kg/day, and only 0.12 kg above it.
- Using indicator amino acid oxidation in eight men, the mean protein requirement was 0.93 g/kg/day and the population-safe figure 1.2 g/kg/day — 41% and 50% above the current EAR of 0.66 and RDA of 0.8.
- NHANES data on 57,980 Americans put average relative protein intake between 1.10 and 1.32 g per kg of ideal bodyweight per day, above the estimated average requirement in every demographic group.
Two numbers do most of the damage in this argument. One is 0.8 grams of protein per kilogram of bodyweight per day, which is the RDA. The other is roughly 1.6, which is where the training literature stops improving. People treat these as rival claims. They are answers to different questions, and once you see which question each one is answering, the argument gets a lot shorter.
What 0.8 g/kg is a measurement of
The RDA is a population-safe floor for adequacy — the intake at which almost nobody runs a deficit. It was never presented as the optimum for building or holding muscle, and reading it that way is the original error.
It may also be low even as a floor. Humayun and colleagues re-measured protein requirement in eight healthy men using indicator amino acid oxidation, feeding graded intakes from 0.1 up to 1.8 g/kg/day. The mean requirement came out at 0.93 g/kg/day and the population-safe figure at 1.2 — 41% and 50% above the current EAR of 0.66 and RDA of 0.8 respectively. When the same biphasic model was applied to the older nitrogen-balance data, it produced 0.91 and 1.0: same direction, smaller gap.
Eight men is eight men, and one technique. But the authors' conclusion — that the current recommendations are too low and need reassessing — has stayed a live position in the field rather than being quietly dropped.
Where the curve flattens for people who lift
Morton and colleagues pooled 49 randomised trials with 1,863 participants, all involving at least six weeks of resistance training. Protein supplementation produced statistically significant but modest average gains: 2.49 kg on one-repetition maximum strength (95% CI 0.64 to 4.33) and 0.30 kg of fat-free mass (95% CI 0.09 to 0.52). Those are the real effect sizes. Nobody puts them on a tub.
The number everybody quotes came from a break-point analysis of 42 study arms and 723 participants: gains in fat-free mass stopped increasing above a total protein intake of 1.62 g/kg/day. What tends to get dropped is the confidence interval, which was 1.03 to 2.20. The plateau is real; its location is fuzzy. Anyone quoting 1.6 to two decimal places is quoting a point estimate with more than a kilogram of uncertainty at each end.
Two other findings in that paper are more useful than the headline. The benefit of supplementation shrank as participant age rose, and it was larger in people who were already resistance-trained — the opposite of how these products are usually marketed to beginners.
Tagawa and colleagues came at the same question from a different angle: 105 articles, 5,402 participants, spline modelling across intakes from 0.5 to 3.5 g/kg/day. Below a total intake of 1.3 g/kg/day, each additional 0.1 g/kg/day was associated with a mean 0.39 kg increase in lean body mass (95% CI 0.36 to 0.41). Above 1.3, the same increment bought 0.12 kg (95% CI 0.11 to 0.14). Different dataset, different inflection point, same shape: steep early, shallow later.
The disclosures worth reading
We will point at this because most write-ups don't. The Morton meta-analysis carries a competing-interest statement noting that its senior author received grant support from the US National Dairy Council, an agency that had funded trials included in the analysis. It was formally corrected two years later specifically to add a disclosure that another author had served on the advisory board of a sports supplement manufacturer while the paper was being written. The Tagawa paper's lead author and several co-authors work in the R&D division of a food company.
None of that makes the findings wrong — these are good papers by serious researchers. It does mean the case for protein supplementation was assembled, in part, by people with commercial ties to protein. Worth holding in mind when a brand that sells powder quotes 1.6 at you.
Does it matter when you eat it?
Mamerow and colleagues fed eight healthy adults two diets identical in calories and identical in total protein, differing only in distribution: roughly 30g at each of three meals, versus 10g, 16g and 63g skewed towards dinner. Twenty-four-hour muscle protein synthesis was 25% higher on the even distribution, and the difference persisted after seven days on each diet.
Read that carefully before rearranging your life around it. Eight people, seven days, and the outcome measured was the rate of muscle protein synthesis — a mechanism, not muscle actually gained. A 25% difference in a synthesis rate over a week is not a promise of 25% more muscle over a year. What it reasonably supports is the unglamorous suggestion that if your breakfast currently contains no protein, putting some there is probably worth more than any other scheduling decision you could make.
So are you already getting enough?
For adequacy, almost certainly. Berryman and colleagues analysed NHANES data covering 57,980 Americans. Relative protein intake averaged 1.10 g per kg of ideal bodyweight per day in adults aged 71 and over, rising to about 1.32 in some adult groups, and every demographic group came out above the estimated average requirement. Protein made up 14 to 16% of total energy intake, and under 1% of any group exceeded the upper end of the acceptable range.
So the average adult sits comfortably clear of the floor and some way short of the training plateau. Closing that gap — from around 1.2 to around 1.6 — is roughly one extra substantial portion of protein a day for most people. That is a grocery problem, not a supplement problem.
What we'd actually tell you
We do not sell protein powder. There isn't one in the LUVO catalogue and there is no plan to add one, so treat the following as free of commercial interest.
If you lift and you want the best-supported target, work towards roughly 1.6 g/kg/day and stop climbing after that — the evidence above that line is absent rather than mixed, which is a different and weaker reason to keep going. Get there with food first. Powder is a convenience for people who find the number hard to hit, not a form of nutrition that food cannot supply. Spread protein across your meals if that is easy, and do not reorganise your week if it isn't. And if you are over 60, the Morton data points towards supplementation doing less rather than more, which is an argument for food and for resistance training rather than for a bigger tub.
The one training supplement we do sell is creatine. That is a separate argument with a separate evidence base, and it is not a protein substitute — nothing is.
Good questions
How much protein do I actually need a day?
For basic adequacy, 0.8 g per kg of bodyweight, though one re-measurement using indicator amino acid oxidation put the population-safe figure closer to 1.2. If you lift weights and want the best-supported target, aim for around 1.6 g/kg/day, where the meta-analytic gains in fat-free mass stop increasing. Above that the evidence is absent rather than mixed.
Do I need protein powder to build muscle?
No. Powder is a convenience for hitting a number, not a form of nutrition food cannot supply. US survey data puts the average adult at 1.10 to 1.32 g per kg of ideal bodyweight per day, so the gap to a training target of about 1.6 is roughly one extra substantial portion a day. We do not sell protein powder, so there is nothing in this answer for us.
Is there any point eating more than 1.6 g of protein per kilo?
Not for muscle, on the current evidence. The break-point analysis behind that figure found no further gains in fat-free mass above 1.62 g/kg/day. Worth knowing the confidence interval ran from 1.03 to 2.20, so the plateau is real but its exact location is fuzzy. Going higher is unlikely to hurt; it is just unlikely to do anything.
Does it matter if I eat all my protein at dinner?
Possibly a little, but the evidence is smaller than the internet suggests. Eight adults eating the same total protein spread evenly across three meals had 24-hour muscle protein synthesis 25% higher than when it was skewed towards dinner. That is a synthesis rate over a week, not muscle gained over a year. Adding protein to a breakfast that has none is the version worth doing.
Does protein supplementation work as well when you're older?
Less well, according to the meta-regression. In 49 trials, the effect of supplementation on fat-free mass gains shrank as participant age increased, and was larger in people already resistance-trained. That is close to the reverse of how these products get marketed. For older adults the stronger levers are total food intake and actually doing the resistance training.
Why doesn't LUVO sell a protein powder?
Because most people can reach the useful intake with food, and a powder would mainly be us selling convenience at a margin. The catalogue has no protein product and there is no plan to add one. If you genuinely struggle to hit your number, a powder is a reasonable tool and plenty of brands make a decent one. It just is not a gap we think we need to fill.
Sources
- Morton RW, 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. View study
- Tagawa R, et al. Dose-response relationship between protein intake and muscle mass increase: a systematic review and meta-analysis of randomized controlled trials. Nutr Rev, 2020. View study
- Humayun MA, Elango R, Ball RO, Pencharz PB. Reevaluation of the protein requirement in young men with the indicator amino acid oxidation technique. Am J Clin Nutr, 2007. View study
- Mamerow MM, et al. Dietary protein distribution positively influences 24-h muscle protein synthesis in healthy adults. J Nutr, 2014. View study
- Berryman CE, Lieberman HR, Fulgoni VL 3rd, Pasiakos SM. Protein intake trends and conformity with the Dietary Reference Intakes in the United States: analysis of the National Health and Nutrition Examination Survey, 2001-2014. Am J Clin Nutr, 2018. View study
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