How much protein I should be eating to build muscle?

For most people aiming to improve body composition or increase strength, 1.8 grams of protein per kg of bodyweight per day is sufficient, provided that at least half of that comes from high-quality sources such as meat, eggs, and dairy.

This number comes from a meta-regression of the literature in 2018 that found the break-off point of maximal muscle growth occurs at 1.6 g/kg/d protein (Morton, Murphy, McKellar, Schoenfeld, Henselmans, Helms, Aragon, Devries, Banfield, Krieger, & Phillips, 2018).

The results were closely replicated by another meta-analysis from Tagawa, Watanabe, Ito, Otsuyama, Nakayama, Sanbongi, et al. in 2022 where they found a protein intake of 1.5 g/kg/d was enough to maximize strength development.

Although research generally finds no additional benefits beyond 1.6 g/kg/d, these calculations are based on averages. There are always some people who could get better results from more protein. To account for this we apply the Three-Sigma rule, and calculate intake recommendation 3 standard deviations above the mean. Based on Lemon, Tarnopolsky, MacDougall, & Atkinson (1992) protein intake estimation this comes to a recommended protein intake of approximately 1.8 g/kg/d or 0.82 g/lb/d. This figure is also supported by a review paper by Phillips & Van Loon (2011).

Theoretically, women might need 10% less protein since their metabolism is comparatively more protein sparing. However this difference found in a meta-analysis by William M. Rand, Peter L. Pellett, and Vernon R. Young (2003) was not statistically significant. Since there is a lack of research directly examining the difference with men and a lack of research supporting less than 1.8 g/kg/d is enough even for women with a bodyweight below 60 kg, the 1.8 g/kg/d protein intake recommendation for female strength trainees ensures optimal progress.

The key takeaway is that 1.8 g/kg/d is the latest evidence-based general recommendation for maximal muscle growth

The popular idea that we need to consume one-gram-per-pound a day (or 2.2 grams per kilogram) likely started with people trying to emulate the dietary practices of professional bodybuilders who use anabolic-androgenic steroids. Performance enhancing drugs can increase protein needs substantially. A 2015 systematic review of the dietary practices of competitive bodybuilders by Spendlove, Mitchell, Gifford, et al. found average protein intakes range from 2.1 to 3.7 g/kg/d in enhanced bodybuilders.

Combine this with the fact that it’s easy round up a .82 intake recommendation to the nearest convenient whole number, and that supplement companies have a strong incentive to promote higher protein intake recommendations, we see a general ‘more is better’ heuristic when it comes to protein, despite any supporting evidence.

Josh Pitzalis

How much protein I should be eating to build muscle?

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