Is it true men grow more muscle quicker than women?
Executive summary
Short answer: no—men do not reliably grow muscle faster than women when growth is measured proportionally; men typically show larger absolute gains because they start with more muscle and higher testosterone, but relative (percentage) hypertrophy and early strength improvements are often similar between sexes [1] [2] [3].
1. Why the question matters: absolute vs. relative gains
The distinction between “faster” and “bigger” is the core of the debate: men generally gain more absolute muscle mass and produce larger absolute strength outputs because they possess greater baseline skeletal muscle and higher circulating androgens, but when researchers compare percentage change from baseline (relative growth), many studies find men and women increase muscle size and strength at comparable rates [1] [2] [3].
2. What controlled training studies report
Randomized and longitudinal resistance‑training experiments often show similar percent increases in muscle size and strength across sexes; for example, a 10‑week upper‑body study reported nearly identical strength gains for men and women (~11.6% for men vs ~11.8% for women) and similar effect sizes [2], and other trials find comparable hypertrophy when measured as percent change [4] [5].
3. The biological reasons behind sex differences in absolute outcomes
Biology explains why absolute outcomes diverge: men typically carry more total muscle mass and higher testosterone, factors that drive higher baseline strength and larger absolute hypertrophy under the same program [1] [6]. Conversely, women have hormonal and molecular features—greater growth‑hormone secretion, estrogen’s role in muscle, and different gene expression patterns (e.g., GRB10, ACVR2A)—that influence growth and repair and help produce similar proportional adaptations [6] [7].
4. Nuance by muscle group, fiber type, and age
Differences are not uniform across the body or lifespan: some evidence shows men may gain more in upper‑body mass and certain fiber‑type responses (e.g., larger absolute upper‑body growth and more Type I fiber hypertrophy in some analyses), while lower‑body and relative gains are often similar [8] [9]. Age changes the picture, too—sex differences in strength emerge during adolescence and women may lose muscle faster with aging in some studies, complicating long‑term comparisons [5] [9].
5. Mechanisms beyond hormones: neuromuscular adaptation and measurement choices
Early training gains tend to reflect neuromuscular adaptation rather than true hypertrophy, a process that appears to run a similar time course in both sexes [2]. How researchers express outcomes—absolute mass vs percentage change, imaging vs circumference, upper vs lower body—strongly affects conclusions, which is why different reviews and popular articles can sound contradictory while citing the same underlying data [4] [3].
6. What this means in practice and for interpreting popular claims
For practical purposes, both men and women respond well to resistance training: women are not inherently “slower” at building muscle in relative terms, though men will often show larger absolute increases and different regional patterns due to baseline mass and androgen exposure [2] [1]. Fitness websites and blogs sometimes oversimplify or emphasize testosterone narratives because they’re attention‑grabbing, so readers should weigh peer‑reviewed trials and meta‑analyses over catchy headlines [6] [10].
7. Limitations and remaining uncertainties
The literature still has gaps: studies differ in training protocols, duration, participant age and training history, and measurement methods, and molecular studies highlight many sex‑specific gene and signaling differences whose functional implications need more longitudinal human research; therefore firm statements about “faster” must acknowledge these methodological limits [7] [5].