The recommendation for protein intake within the evidence-based fitness community has, for a long time, been a simple “1 gram per pound of bodyweight”.

While this is certainly a simple heuristic, is there any merit to this recommendation? Is this really optimal for muscle growth? Have we lost nuance for simplicity’s sake?

Reading time: 3-5 minutes

Take-aways. NOTE: This article is due for an overhaul; new evidence suggests the take-aways here are slightly off-base.

1. If you aim for ~1.6g/kg of protein per day, you’re likely to optimize your muscle growth (and probably strength gains, too).

   1. You could go higher - as high as a gram per pound - but it’s probably not beneficial for most people.

2. You may see a greater benefit to increasing your protein intake if you’ve been training for a while. Older trainees very likely need to increase protein intake by a larger amount to see a positive impact.

3. Personally, if I manage to get ~1.6g/kg of relatively high-quality protein per day - ideally spread out over 3-5 meals - that’s the protein box ticked.

This is where a meta-analysis and meta-regression by Morton and colleagues comes in.

In order to find what the impact of protein on gains in strength and muscle mass were - and what the optimal protein intake was to augment these - the authors combined data from 49 total studies.

Here’s what they found.

Similar results were found for measures of muscle hypertrophy. Increasing protein intake resulted in a bit more muscle gain over the course of a training program (+0.3kg; 95% CI: [0.09;0.52]). Other measurements of muscle hypertrophy analysed also mirrored these results.

Interestingly, for both 1RM improvements and increases in FFM, protein-induced gains seemed greater in trained vs untrained participants. So, increasing protein intake may be particularly beneficial in trained participants.

The impact of age on the effects of increasing protein intake on muscle growth was also analysed. It seems that greater protein intakes are more beneficial in younger vs older trainees. This may be because older individuals generally require higher protein intakes to optimize muscle growth and there was only a difference of 20g between groups, on average. So, it may just “not have been enough protein” for the older participants to make a difference.

Finally, the authors performed a meta-regression, seeking to determine what protein intake maximised increases in fat-free mass. Using a segmental linear regression, it was determined that greater protein intakes promoted greater gains in fat-free mass up until an intake of, on average, 1.6g of protein per kilogram of bodyweight per day. It’s worth noting that this represents the average/mean optimal protein intake; the 95% CI ranged from 1.03 to 2.2g/kg/day. So, if you really wanted to cover your bases, you could go as high as 2.2g/kg/day (1 gram per pound).. but there’s a good chance it would be overkill.

If you’d like to chat about this study, feel free to comment below.

If you’re looking for an expert to handle your training and nutrition for you, check out our coaching services.