Study
Influence of age, sex, and type of exercise on the efficacy of creatine supplementation on lean body mass: A systematic review and meta-analysis of randomized clinical trials
Across 35 RCTs and 1,192 participants, creatine raised lean body mass by 0.68 kg overall (95% CI 0.26 to 1.11) and by 1.10 kg when combined with resistance training (95% CI 0.56 to 1.65), but by 0.03 kg without exercise.
Felipe Delpino and colleagues searched PubMed, SPORTDiscus, Web of Science and Scopus to May 2022 and pooled 35 RCTs covering 1,192 participants. Animal studies and disease-specific populations were excluded. The outcome was lean body mass. Subgroup analyses split results by age, sex and exercise type. The protocol was registered as PROSPERO CRD42020207122.
Overall, creatine increased lean body mass by 0.68 kg (95% CI 0.26 to 1.11). Exercise type decided the size of the effect. With resistance training the gain was 1.10 kg (95% CI 0.56 to 1.65) and held across ages. With mixed exercise the gain was 0.74 kg but the interval spanned zero (95% CI -3.89 to 5.36). Without any exercise the gain was 0.03 kg (95% CI -0.65 to 0.70), which is nothing.
Sex mattered too. Males gained 1.46 kg (95% CI 0.47 to 2.46). Females gained 0.29 kg (95% CI -0.43 to 1.01), which was not statistically significant. This is the clearest quantitative statement of the core creatine claim: about 1 kg of extra lean mass, and only alongside resistance training.
In conclusion, the addition of creatine supplementation to a resistance training program increases LBM.
Lean body mass is not the same as contractile muscle. Creatine draws water into muscle cells, and this meta-analysis cannot separate intracellular water from myofibrillar protein, so part of the 1.10 kg is likely fluid. The abstract does not report doses, durations or heterogeneity statistics, so the pooled estimate cannot be tied to a specific protocol. The mixed-exercise subgroup interval was extremely wide (-3.89 to 5.36 kg), signalling very few or very inconsistent trials. The female estimate was null, and the authors do not resolve whether that reflects a real sex difference or fewer female participants. Scott Forbes and Darren Candow are frequent creatine authors with industry ties reported in other papers. Trials in people with specific diseases were excluded, so the result applies to generally healthy participants only.
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