In women, supplements barely added to exercise gains

Muscle and bone decline progressively across a woman's life, with the pace picking up through the menopausal transition, so the search for anything that adds to the known benefits of training is a live one. Protein, amino acids and creatine are all marketed on that promise, but most of the supporting evidence has come from studies of adults aged 65 and above, where the starting point and hormonal context are different. That leaves a gap for women earlier in life and around menopause, whose metabolic situation is shaped by reproductive hormones. This review asked whether supplementation genuinely adds to exercise for muscle mass, strength and bone.

The team searched eight databases from inception to July 2025 — CINAHL, ClinicalTrials.gov, the Cochrane Central Register of Controlled Trials, Embase, PsycINFO, MEDLINE/PubMed, Scopus and Web of Science — for randomised controlled trials in women across reproductive stages. Eligible interventions paired structured exercise with whole proteins, amino acids, amino acid derivatives or protein-derived peptides, and comparators were exercise alone or placebo plus exercise. Fourteen trials with 763 women qualified: five on whole-protein supplements, six on amino acids and derivatives, and three on creatine monohydrate. Primary outcomes were muscle mass measures, with strength, bone parameters, body composition and adverse events secondary, pooled as Hedges' g with random-effects models.

On the primary outcomes there was nothing: skeletal muscle mass g = 0.065 (95% CI -0.353 to 0.482, p = 0.762), appendicular lean mass g = 0.197 (-0.177 to 0.571, p = 0.302) and fat-free mass g = 0.069 (-0.110 to 0.249, p = 0.447). Bone outcomes were also flat, with bone mineral content g = 0.195 (p = 0.421) and bone mineral density g = 0.087 (p = 0.430). Two strength measures did reach significance: bench press g = 0.279 (0.008 to 0.550, p = 0.043) and handgrip strength g = 0.412 (0.039 to 0.786, p = 0.031). No increase in adverse events was observed across the trials.

This tempers the assumption, largely built on older-adult research, that supplementing on top of training reliably adds muscle. It does not say supplements do nothing — the selective upper-body strength gains, which the authors link particularly to creatine studies, suggest a narrower effect than the marketing implies. The mixing of proteins, amino acids and creatine into one pooled analysis is a real limitation, and the authors call for longer interventions of at least 12 months, site-specific bone measurements and direct head-to-head comparisons of supplement types. The confidence intervals were wide enough that a modest true effect cannot be ruled out.

The dependable part of the package here is the exercise: it delivered musculoskeletal benefits, and the added supplements did not reliably move muscle mass or bone density in these women. If your goal is lean mass or bone, this is a reason to prioritise the training programme before the tub. The small gains in bench press and grip strength are worth noting rather than dismissing, especially for anyone interested in creatine, but they came from a handful of trials. No safety signal appeared, so this is a question of value rather than risk.