In a 12-week randomized trial published in the Journal of the International Society of Sports Nutrition on August 11, 2026, sedentary adults aged 45 to 65 who took 10 grams of creatine monohydrate a day without starting an exercise program gained about 1.1 kilograms (roughly 2.4 pounds) of lean tissue by DXA scan, while the no-exercise placebo group lost a small amount. So what does creatine do if you train, and what does it do if you do not?

What the 2026 no-exercise trial found

The Texas A&M trial randomized 73 sedentary adults (64 finished; 40 women, 24 men; average age about 54) to creatine or a maltodextrin placebo, double-blind, as two 5-gram doses a day for 12 weeks. Participants chose whether to join a supervised program of three resistance and aerobic sessions a week plus a calorie deficit, and were randomized to the supplement inside that choice. Exercise was self-selected, not randomized, so only creatine against placebo within each group is a clean comparison.

The creatine groups gained fat-free mass relative to placebo. Strength gains were largest where creatine was paired with training (leg press one-repetition maximum rose about 30 percent), though the no-exercise creatine group also outperformed its placebo group on bench press. Blood creatinine rose slightly in the creatine groups while staying inside normal ranges. The authors name small groups (13 to 20 per arm), self-selected exercise, imputed missing data and many exploratory outcomes without adjustment as limits. Funding came from a foundation gift to Texas A&M; the creatine supplier, Alzchem, provided the product, and the senior author chairs that company's scientific advisory board.

Is the lean tissue muscle?

This is the question the trial cannot answer on its own. DXA reports lean soft tissue, and water inside muscle counts as lean tissue. The ISSN position stand on creatine (same journal, 2017) describes short-term fluid retention of about 0.5 to 1.0 liter during loading and names weight gain as the only consistently reported side effect. A liter of water is a kilogram on the scan.

A 2025 randomized trial in Nutrients makes the point. Sixty-three untrained adults aged 18 to 50 took 5 grams of creatine a day or nothing, starting with a seven-day wash-in before training. During that week, the creatine group gained about 0.5 kilograms more lean mass than controls, a change the authors attribute to fluid shifts rather than new tissue, and one inside the scanner's own margin of error. Over the following 12 weeks of lifting, both groups gained roughly 2 kilograms and creatine added nothing over control. The authors flag uncontrolled hydration, a single-blind design, and one dose tested.

What the pooled evidence says

Two meta-analyses from 2026 split the question by training status. In Frontiers in Nutrition (April 8, 2026), a review of 37 randomized trials in healthy men aged 18 to 30 found that with resistance training, creatine added about 3.4 kilograms of fat-free mass and 2.7 kilograms of lean body mass over placebo. Without resistance training, the pooled change was not different from zero. Most trials used a loading phase near 20 grams a day followed by 2 to 10 grams a day, and the authors reported no funding. They name short trials, mixed non-training conditions and possible water retention as limits.

In the Journal of the International Society of Sports Nutrition (online May 16, 2026), a review of seven randomized trials in 608 postmenopausal women (average age about 62, 12 to 104 weeks) found lean mass about 0.37 kilograms higher with creatine and leg press strength about 7.5 kilograms higher. The effects appeared where at least 5 grams a day was paired with resistance training; trials using 3 grams a day or less without training showed no measurable effect. Bone density did not change and adverse events matched placebo. Two authors disclose ties to the ISSN and to Alzchem.

The landmark trial behind the training effect

That pattern goes back to work such as the 1999 trial in Medicine and Science in Sports and Exercise, in which 19 resistance-trained men lifted for 12 weeks on creatine (25 grams a day for a week, then 5 grams a day) or placebo. Fat-free mass rose 6.3 percent on creatine against 3.1 percent on placebo, muscle fiber cross-sections grew two to three times as much, and bench press training volume was higher in the creatine group during weeks five to eight. The authors' reading: creatine lets people do more quality work per session, and the extra work builds the muscle. That mechanism needs training.

Doses the research used, and safety

The ISSN position stand describes two ways trials have raised muscle creatine by roughly 20 to 40 percent: a loading phase of about 0.3 grams per kilogram a day for five to seven days followed by 3 to 5 grams a day, or 3 grams a day for about 28 days. The 2026 trials above used 5 or 10 grams a day with no loading.

On safety, the position stand reports no compelling evidence that creatine harms kidney function in healthy people or the clinical groups studied, no increase in dehydration or cramping, and no rise in injury or stomach upset, with doses up to 30 grams a day for up to five years described as tolerated in clinical populations. It suggests people with kidney disease consult a physician. The paper was supported by the Council for Responsible Nutrition, a supplement trade group, and several authors disclose industry ties.

With resistance training, creatine's effect on lean mass and strength is consistent across decades of trials. Without training, the evidence is one small 2026 trial showing a DXA gain that is at least partly water, against two pooled analyses in which creatine alone did not move lean mass. The questions to bring to your clinician: your kidney history, your medications, and which outcome you are after.

This article reports research and expert guidance. It is not medical advice. Talk to your clinician before changing medication, treatment or a medical diet.

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