0.8 grams. That is the current U.S. Recommended Dietary Allowance for protein per kilogram of body weight, per day. It is the number governments use. It is also, according to the fitness internet, practically a death sentence for your gains. Influencers will tell you that you need at least double that. Some will tell you triple. One popular coaching account I saw recently was recommending 1 gram per pound of body weight, which for a 185-pound person works out to roughly 2.8 g/kg/day. No citation. No study. Just confidence and a before-and-after photo.
Here is what the research actually says.
The Number the Evidence Keeps Landing On
Let's start with the most important meta-analysis in this space. Morton et al. analyzed 49 studies involving 1,863 participants and identified a breakpoint: with protein supplementation, protein intakes at amounts greater than roughly 1.6 g/kg/day do not further contribute to resistance exercise training-induced gains in fat-free mass. That study has been cited hundreds of times and remains the backbone of current sports nutrition guidance.
Critics will point out, correctly, that the breakpoint was not quite statistically significant (p = 0.079) and that the confidence interval was too broad for precision, and most studies included untrained participants, whose protein requirements differ from those of trained athletes. Fair. One meta-analysis is not the end of the conversation. But here is where the cumulative evidence becomes impossible to dismiss: multiple independent teams keep arriving at the same approximate number.
The 2022 meta-analysis published in the Journal of Cachexia, Sarcopenia and Muscle, which drew on 74 randomized controlled trials, found that the effect on lean body mass was significant in subjects 65 and older ingesting 1.2 to 1.59 g of protein/kg/day, and for younger subjects under 65 ingesting at or above 1.6 g of protein/kg/day submitted to resistance exercise. The overall conclusion was restrained: increasing daily protein ingestion results in small additional gains in lean body mass and lower body muscle strength gains in healthy adults enrolled in resistance exercise training. Small. That word matters. The effect is real. It is not dramatic.
A separate meta-analysis in Nutrition Reviews, which analyzed data from 5,402 participants across 105 articles, found that the rate of increase in the effect of protein supplementation rapidly diminished after 1.3 g/kg/day was exceeded, and resistance training markedly suppressed this decline. Read the implication: training itself extends how much protein your body can productively use. You cannot out-supplement a bad training program, and you cannot out-eat a missing one.
A 2025 RCT published in Scientific Reports further suggested that when combining protein intake and resistance exercise, limiting protein intake to 1.5 g/kg/day may be the optimal dose for increasing muscle mass and strength, while also limiting excessive protein intake. The researchers specifically designed the study to isolate the synergistic effect of protein and exercise, controlling for the confounders that plague earlier work. Sample size was modest (n=34), so I wouldn't bet the house on 1.5 as a magic number. But the directional signal is consistent with everything else.
What You're Actually Buying at 2.5 g/kg
So why does the fitness industry keep pushing numbers well above 1.6? Because protein powder is profitable and because a handful of studies do show marginal benefit at higher intakes, particularly during caloric restriction or in highly trained athletes. Leading sports nutrition authorities such as the International Society of Sport Nutrition and the American College of Sports Medicine advocate for substantially higher daily protein intake for exercising individuals, typically ranging from 1.4 to 2.0 grams per kilogram of body weight per day. That upper range exists for a reason: it provides a buffer during hard training blocks and energy deficits. During a cut, when your body is burning amino acids for fuel, higher intake makes physiological sense.
But that is not who is buying the 5-pound tubs at the supplement store. The average person lifting three days a week in a caloric maintenance state does not need 2.4 g/kg. A 2021 RCT published in the American Journal of Physiology, which randomized 50 middle-aged adults to either moderate (~1.0 g/kg/day) or higher (~1.6 g/kg/day) protein intake during a 10-week resistance training program, found that maximal strength for all upper and lower body exercises significantly increased with no effect of protein intake, and higher protein intake above moderate amounts does not potentiate resistance training adaptations in previously untrained middle-aged adults. The effect size was essentially zero on strength outcomes between the two groups. The training worked. The extra protein did not add to it.
What about the quality and source of protein? At least on that front, the news is good and underreported. Recent evidence suggests that both animal and plant proteins support strength and hypertrophy gains when paired with resistance training and adequate protein intake. A 2025 RCT found similar muscle adaptations between plant-based and animal-based protein blends in untrained young men following identical resistance programs. If you're eating enough total protein, the source matters considerably less than the supplement industry's whey-vs-everything-else wars suggest.
What the RDA Gets Wrong, and Why 1.6 Is the Practical Target
To be clear: the RDA of 0.8 g/kg is almost certainly too low for anyone training seriously. The current RDA is based on the amount required to maintain nitrogen balance and prevent muscle loss; extending these recommendations to active individuals who are looking to build muscle may not be appropriate. That is an important distinction. Preventing deficiency and optimizing adaptation are entirely different biological targets. The government's number was never designed for people doing progressive overload three to five times per week.
There is also an age variable that deserves more attention than it gets. Older subjects would likely respond differently since anabolic resistance develops with aging, and higher per-meal protein doses are postulated to be necessary to stimulate muscle protein synthesis in this population. For someone over 65, pushing toward the higher end of 1.6 g/kg is genuinely supported by the evidence, not just aspirational broscience.
The practical recommendation, grounded in the current body of randomized controlled trial evidence: aim for 1.6 g/kg of body weight per day, distributed across three to four meals. If you're in a caloric deficit or over 60, trend toward the higher end. A high-protein diet enhances muscular performance and skeletal muscle mass in resistance-trained individuals, irrespective of intake timing; the total daily protein intake appears to be the primary factor in facilitating muscle growth induced by exercise. Timing is secondary. Totals are primary.
Kai has been tracking his protein to the gram for two years, swearing the higher numbers feel better. I believe him, for Kai. n=1 is not evidence. It is an anecdote. But the RCTs are telling a clear story: get to 1.6, lift progressively, sleep adequately. Everything above that is optional, and the effect sizes tell you exactly how optional.
The supplement industry will not tell you that. The meta-analyses will.
