Muscular man drinking protein shake at the crossfit gym

Key Topic

If you’re aiming to gain muscle mass, you have likely heard the golden rule of protein intake: consume 1.6-2.2g per kilo of body weight per day. But is this range the optimal target, or should you be aiming higher? In this podcast, we dive into the science behind this recommendation and discuss whether adjusting your protein intake might make a difference in muscle growth. Drawing insights from large reviews by Morten and colleagues, Brad Schoenfeld, and Alan Aragon, along with a thought-provoking article from Greg Nuckols, we will explore how protein needs vary depending on factors like body composition and calorie intake. Keep reading to find out what this all means for your muscle-building journey!

Statistics

  • The original article largely came to the conclusion that 1.62g/kg appeared to be the point at which muscle growth did not increase beyond.
  • The 2.2g/kg number is kind of just added on top to account for outliers. Technically it’s based on a confidence interval, but I don’t want to go deep into statistics.

Challenges

  • A big challenge of the original interpretation was just digging into the statistics. For example the confidence interval thing. If we are using confidence intervals, technically the range 1.03-2.2g/kg was what it comes out as. And obviously that isn’t helpful haha.
  • He also highlighted that there was a big lack of research included that actually looked beyond 2.2g/kg.
  • But then he made a point that even within the study, there were some graphs that found going a bit beyond 1.6g/kg led to even more muscle growth than 1.6g/kg appeared to. This largely just isn’t something that was latched onto and talked about in the community.
  • In all 5 studies where they consumed more than 1.6g/kg, they gained more muscle.

Difficulties Interpreting the Research

  • Trying to keep this simple, Greg also highlighted in his article, some huge things that make this research hard to interpret perfectly.
  • For the study to be relevant it has to compare higher vs lower intake. Especially because people’s training will be different in different studies.
    • Example: If you got a group of experienced lifters to eat high protein but do a low volume of training, they would get worse results than a study looking at new lifters eating low protein but training hard. This wouldn’t be a fair reflection. 
  • And people’s historical intake could matter a bit too.
    • Example: If people ate high protein prior to the study and then dropped their intake, it could influence outcomes.
  •  another variable is lifting duration. This research looked at both experienced and inexperienced lifters. What if one group needs more than the other? It was all mixed in together with this analysis.
  • And finally Self reported data kinda sucks, which can  influence the outcomes of a lot of studies. 

Slightly Newer Research

  • A 2020 review had a few differences. It separated lifters and non-lifters.
  • They also had a much broader range of studies included. They even allowed weight loss studies to be included.
  • Instantly this raises the question of whether this would influence it because we know protein needs are higher in a deficit.
  • Their chart actually found an increase in muscle growth all the way up to 3g/kg. But there are two main caveats:
  1. There isn’t much research beyond that intake. So just because it stopped there in this review doesn’t mean it ACTUALLY stops there.
  2. There are clearly diminishing returns. Once the chart hit about 1.6g/kg the increase in muscle per gram of protein progressively became less and less.
  3. As mentioned, this can be skewed a bit by protein needs being higher in a deficit.
  • Only 12.5% of the included studies were weight loss focused, so if it has skewed stuff, it’s not a major factor.

The Latest Research

  • The most recent meta-analysis on this topic was in 2022.
  • It was similar to the Morton one, just with newer research.
  • Basically it came to this same diminishing returns logic. 
  • If there is a cut-off, the charts indicate that there were still increases in muscle growth up to 2.3-2.4g/kg body weight.

Interpretations

  • So the first interpretation is that needs are slightly higher than the 1.6-2.2g/kg range if you want to MAXIMISE things.
  • A solid and simple target proposed is 2.0g/kg, scaling based on how lean you are e.g. if you have a high body fat percentage, you can go lower per total kg of body weight.
  • A “better safe than sorry” approach proposed was ~2.4g/kg.
  • But it’s also worth emphasising that even 1.2-1.5g/kg gets you almost as much muscle growth. People can still make great progress at that level. Going higher is just relevant to maximise things.

Summary

  • Overall, this hasn’t shifted our perspective much.
  • But we think it make sense to shift our messaging slightly. 
  • We have both used the 1.6-2.2g/kg range a fair bit, in a bid for simplicity.
    • Our job as dietitians is to interpret research and guidelines like this and convert it to simple and practical advice for our clients 
  • But Thinking through it deeper, saying a simple number like 2.0g/kg arguably works even better and this is personally where I had shifted my approach to a while ago when talking with clients 1-on-1.
  • But then it would be about individualising from there with a combo of the “better safe than sorry” and scaling it based on leanness. 
  • Although, I also like to consider the ROI on things like time, money & effort in regards to is it actually worthwhile adding 20% more complexity to your nutrition for 1-2% extra gains.
    • This is super relevant to that point of diminishing returns concept.
    • Ideally we maximise protein intake as much as possible WHILST factoring in these others things and whether it is worth increasing it past a certain point. 

Relevant Blogs/Research

Relevant Studies: 

Relevant Blog Post: