Short answer
For a 70 kg (154 lb) person, about 113 g a day. The benefit leveled off at about 91 to 113 g a day, and 154 g is a generous amount. Eating 307 g a day did not add more lean mass (muscle and everything except fat) over 8 weeks.
How much protein a day do you need to build muscle?
'The more you eat, the more you grow.' Is that right?
A common tip is to eat as much protein as possible to build muscle. But up to what amount does eating more keep adding muscle? We checked how much muscle was gained at different daily intakes.
Adding protein while training built more
30 kg more across 49 studies and 1,863 people
In an analysis that pooled 49 studies with 1,863 people, those who added protein while strength training gained 0.30 kg more lean mass (muscle and everything except fat). A 2022 analysis that pooled 74 studies also found that eating more protein while training added a little more lean mass.
Where did the gains level off?
For 70 kg body weight, about 91 to 113 g a day
In the 49-study analysis, lean mass stopped rising once daily protein went above about 113 g for a 70 kg (154 lb) person. In an analysis of 105 studies with 5,402 people that also included studies without exercise, above about 91 g, each extra 7 g added 0.12 kg of lean mass instead of 0.39 kg. Both analyses showed the benefit leveling off in the 90 to 110 g range.
Needs measured inside the body were similar
About 119 g on a rest day, 154 g to be generous
In a study where 8 people ate varying amounts of protein on a rest day and their needs were measured from how much amino acid was burned, the average need was about 119 g a day for 70 kg body weight, and the generous recommended amount was about 154 g. That is about 2.6 times the government recommendation.
What about eating a huge amount?
Even 307 g a day did not change the body more
30 people kept their training the same for 8 weeks, and only one group raised protein to the level of about 308 g a day for 70 kg body weight. The actual average was 307 g a day, versus 138 g for the group eating as usual. Body weight, body fat, and lean mass showed no difference.
Summary: about 113 g a day for 70 kg
154 g is generous, and even 307 g added no more
The benefit of protein for muscle leveled off at about 91 to 113 g a day for 70 kg body weight. The need measured inside the body on a rest day was about 119 g, and even a generous amount is 154 g. Eating 307 g a day did not add more lean mass over 8 weeks.
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