Upper Body Muscle Mass Easier to Gain for Men; Lower Body Mass Easier for Women

Does Gender Affect Muscle Mass Outcomes?

Yes, but not without caveats. A recent meta-analysis suggests that men gain more muscle than women “as an absolute number,” as Dr. Layne Norton said. “Absolute” means that if a male athlete and female athlete put on the same percentage of muscle mass, the heavier male athlete will have put on more pounds of muscle.

However, when accounting for the percentage of their starting lean body mass, gender did not influence muscle gains; men and women gain approximately the same.

What Does the Research Say?

A 2024 meta-analysis published in [Journal] found that men gain more muscle than women, but only in their upper bodies. When accounting for starting lean body mass, participants gained similar muscle mass regardless of gender.

The same study included additional studies that involved over 1,200 male participants and over 1,500 female participants, all of whom followed the same training program. The results remained consistent: male participants gained more muscle mass than women, but only in their upper bodies.

Why Do Men Gain More Muscle Mass?

Testosterone is often cited as a key factor in muscle gain, as it increases protein synthesis. However, it’s not the only factor at play. The underlying detail as to why men can gain more muscle mass than women in absolute terms revolves around their testosterone exposure during puberty, which naturally positions them to have more muscle mass.

Dr. Norton suggests that this is why elite female powerlifters’ overwhelmingly strong squats compared to relatively weaker bench presses may be attributed to their ability to gain more muscle mass in their lower bodies.

What’s the Takeaway?

If you train consistently in the gym, prioritizing progressive overload, with proper nutrition and recovery to support that training, you should be able to put on appreciable muscle mass regardless of gender.

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References

1. Refalo, Martin & Nuckols, Greg & Galpin, A & Gallagher, Iain & Hamilton, David & Fyfe, Jackson. (2024). Sex Differences in Absolute and Relative Changes in Muscle Size following Resistance Training in Healthy Adults: A Systematic Review with Bayesian Meta-Analysis.
2. Griggs, R. C., Kingston, W., Jozefowicz, R. F., Herr, B. E., Forbes, G., & Halliday, D. (1989). Effect of testosterone on muscle mass and muscle protein synthesis.