Do guys and girls grow muscle the same way?
Sex differences in absolute and relative changes in muscle size following resistance training in healthy adults: a systematic review with Bayesian meta-analysis
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Type II fiber growth is identical between sexes, despite men having higher testosterone.
Most people assume testosterone drives muscle growth differences—but here, the fibers that respond most to lifting (fast-twitch) grow the same in both sexes.
Practical Takeaways
Women should stop comparing their absolute muscle gains to men’s—focus on their own percentage progress. The same program, same effort, same results—relative to baseline.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Type II fiber growth is identical between sexes, despite men having higher testosterone.
Most people assume testosterone drives muscle growth differences—but here, the fibers that respond most to lifting (fast-twitch) grow the same in both sexes.
Practical Takeaways
Women should stop comparing their absolute muscle gains to men’s—focus on their own percentage progress. The same program, same effort, same results—relative to baseline.
Publication
Journal
PeerJ
Year
2025
Authors
Martin C. Refalo, Greg Nuckols, Andrew J. Galpin, Iain J. Gallagher, D. L. Hamilton, J. Fyfe
Related Content
Claims (6)
Women and men gain muscle at about the same rate relative to how much muscle they started with, but women end up gaining less total muscle because they usually start with less muscle to begin with.
When men and women do strength training, their fast-twitch muscle fibers grow about the same amount—so sex doesn’t really make a difference in how much these muscles get bigger.
When men and women in their late teens to mid-40s do strength training, they both gain muscle at about the same rate—men might gain a tiny bit more, but it’s so small it doesn’t really mean one sex builds muscle better than the other.
Men tend to gain a little more muscle than women from weight training, not because their muscles grow better, but because they start with more muscle to begin with.
When men and women do strength training, men tend to build more upper-body muscle than women do, and this difference is bigger in the upper body than in the legs—probably because men start out with more upper-body muscle to begin with.