Purpose The aim was to perform a meta-analysis of studies examining the effects of ß-hydroxy-ß-methylbutyrate (HMB) supplementation on hormonal adaptations after resistance training. Methods PubMed, Directory of Open Access Journals, Google Scholar and Web of Science were systematically searched up to June 2021 and updated in July 2022. The Cochrane Collaboration tool for evaluating the risk of bias was applied for assessing the studies' quality and then eight studies were included in the review. The random effects model was applied to estimate the overall effect. Results The HMB group showed greater adaptive changes in cortisol levels in comparison to placebo (PL) group after resistance training (ES; - 0.2 vs. 0.08, p = 0.041, delta%; - 2.5 vs. 1.2, p = 0.1). Similarly, the HMB group indicated greater adaptations in testosterone (ES; 0.44 vs. 0.02, p = 0.02, delta%; 13.4 vs. 3.2, p = 0.02) and IGF-1 (ES; 0.32 vs. 0.13, p = 0.001, delta%; 3.75 vs. 1.75, p = 0.01) levels after training intervention. There was no significant difference between the HMB and PL groups in growth hormone changes following resistance training (ES; 0.77 vs. 0.2, p = 0.8, delta%; 55.3 vs. 11.7, p = 0.43). Conclusions The results of this meta-analysis demonstrated the efficacy of HMB supplementation (3 g daily HMB for 7 weeks) to provide greater changes compared with placebo supplementation in resting hormonal concentrations (i.e., testosterone, cortisol and IGF-1).
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