Iron deficiency significantly reduced MuSC proliferation (−10.2% Ki67+ MuSC at 10 dpi, p < 0.01, n = 5) and myoblast EdU incorporation (−18.1%, p < 0.001), leading to smaller regenerating myofibres (−22.7% median cross‐sectional area at 30 dpi, p < 0.01, n = 3) and impaired muscle mass recovery (males: −13.9% p < 0.001, females: −9.4% p < 0.05, n = 6). Here, MKI67 is linked to nutritional disorder.