How much protein should you eat per day to build muscle?
Well, the most comprehensive meta-analysis we have to reference was done by Robert Mortan and a bunch of other absolute Jedi's in the sports science world. We have Brad Schoenfeld, Menno Henselmans, Eric Helms, the list goes on, the kind of sports science Jedi's you want to have involved in your meta-analysis, so you know their review is going to kick ass! According to this meta-analysis, the average amount of protein required to maximise lean mass is ~1.6 grams per kg of body weight per day. Which isn't that much; my son probably gets more than that, and he's four. Nah, that's a lie, unless chips have more protein than I believe they do, chips being a quintessential staple in any four-year-olds diet.
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My review of this study
I think this 1.6 grams of protein per kg of body weight is a great goal; it's sensible, realistic and evidently optimal. In fact, it showed that protein intakes at amounts greater than ~1.6 grams per kg of body weight per day do not further contribute to resistance training induced gains in fat-free mass. This means that many people will see no muscle-building benefit beyond 1.6 grams per kg of body weight per day. If you're already exceeding 1.6 grams, and due to the multiple benefits of high protein diets, you might well be, don't feel the need to drop the chicken breast just yet. In this review, only 4 out of the 49 included studies were on people with resistance training experience, and of the few studies that used resistance training, none of the participant's were in a caloric deficit. Even with this review showing no benefit beyond 1.6 grams, it did also state that ‘it may be prudent to recommend ~2.2 grams per kg of body weight per day for those seeking to maximise resistance training-induced gains in fat-free mass’.
I agree; many people will benefit from consuming a much higher protein intake. The more you're exercising and want to hold onto muscle tissue or further develop it when in a caloric deficit, the more protein you will need. A review done by Hector and Phillips on protein recommendations for elite athletes recommended between 1.6-2.4 grams per kg of body weight per day and stated that 'the severity of the caloric deficit and type and intensity of training performed by the athlete will influence at what end of this range athletes choose to be'.
Most people should aim for 1.6 grams per kg of body weight per day
For most people, 1.6 grams per kg of body weight is enough to optimise muscle protein synthesis, but if you want to err on the side of caution, then play it safe and aim for more. Like all things, we need to base our recommendations on the individual and consider multiple factors beyond just bodyweight. Most of you who work with me (I love you guys!) eat around 1.8 grams of protein per kg of your body weight. This is because many of you are in a caloric deficit, are lifting weights regularly and possibly even have a step target. Essentially you are super active, and due to these factors, your protein needs increase. On the other hand, I do have clients consuming under 1.6 grams per kg of their body weight, as 1.6 grams would be unrealistic given the calories required to induce weight loss in that individual. Striving for more protein can potentially take someone from a caloric deficit, to a surplus. We also need to consider body fat percentage, if someone is over 100 kg and is built like the 38th Governor of California, then they need more protein compared to someone who is the same weight with less muscle mass.
Summary
To summarise, 1.6 grams per kg of body weight is a great amount for most people, but if you're super active, pumping iron, and in a calorie deficit, you may well benefit from consuming more. If someone comes to me looking to maximise the hell out of their muscle-building potential or has aspirations to jump on stage covered in baby oil and a copious amount of fake tan. Then I'm likely to recommend an amount above 1.6 grams per kg of body weight, as we want to do everything possible to squeeze out all potential gains. In fact, I have a handful of clients who are hitting slightly above 2.4 grams, and that's fine — there's nothing to lose and possibly extra to gain! If you're not a fan of eating the leanest sources of protein with each meal or chugging down protein shakes like an alcoholic with a bottle of Jack, don’t worry, as you can take solace in the fact that you may well be maximising your potential by consuming just 1.6 grams per kg of your body weight, a sensible and realistic target for many!