Does Creatine Cause Weight Gain? What the Recent Trials Measured

Creatine is the most widely taken supplement in the gym and increasingly outside it, and the commonest reason people stop taking it is the number on the scale. The research published since 2024 is unusually good at separating three questions that normally get merged: whether total weight rises, whether body fat rises, and whether any of it is new muscle. The answers are different from each other.

TL;DR

• Weight does rise, modestly. Pooled across 63 trials, adding creatine to resistance training produced a small increase in body mass that the authors describe as primarily lean body mass.
• Fat does not rise. The same analysis found no statistically significant change in fat mass at all.
• "Body fat percentage falls" is arithmetic, not fat loss. If lean mass rises and fat mass stays put, the percentage drops on its own. No recent analysis has found creatine reduces absolute fat.
• The first week is where the confusion starts. In a 2025 trial, seven days of creatine added half a kilo of DXA-measured lean mass before any training had happened.
• That early gain did not turn into extra muscle. Over the following twelve weeks of resistance training, the creatine group and the control group gained the same two kilos.
• Dose appears to matter, and so does training. In postmenopausal women, 5g a day or more alongside resistance training produced small gains; 3g or less without training produced no measurable effect.
• Averages hide individuals. The pooled lean-mass estimate in that review was positive, but its prediction interval crossed zero, meaning a future trial could find nothing.

What the pooled trials say about the scale

The largest recent synthesis is a three-level meta-analysis published in the Journal of the International Society of Sports Nutrition in 2026, covering 63 studies and 1,489 participants, with the literature searched to 21 April 2025. It compared resistance training plus creatine against resistance training alone, which is the comparison that matters to anyone already exercising.

Body mass increased, but barely: a standardised effect size of 0.12, significant at p=0.04. Standardised effect sizes express a difference in units of the spread between people rather than in kilograms, and 0.12 sits at the bottom of what researchers conventionally call small. Lean mass rose more convincingly at 0.30, and strength more convincingly still, at 0.54 for upper body and 0.55 for lower body. The authors' summary is that the modest increase in total body weight was primarily attributable to gains in lean body mass. That framing is worth holding on to, because weight going up and muscle going up are not the same observation, and establishing the second requires more than a reading on a scale.

It is not fat

On fat mass, the same analysis found an effect size of −0.10 at p=0.14. That is not statistically significant, which means the trials did not detect a change in either direction. Body fat percentage did fall, at −0.14 and p=0.02, and this is where a great deal of coverage goes wrong.

Body fat percentage is a ratio. If lean mass increases while fat mass stays where it is, the percentage falls automatically, without a gram of fat having been lost. The two findings sitting side by side — fat mass unchanged, fat percentage slightly down — are the signature of exactly that arithmetic. The defensible conclusion is that creatine does not add fat. It is not evidence that creatine removes any.

The first week is the misleading part

The clearest demonstration of what the scale is picking up came from a randomised trial published in Nutrients in 2025. Sixty-three participants, 34 women and 29 men, with a mean age of 31, took 5g of creatine a day across a thirteen-week protocol: a seven-day wash-in, then twelve weeks of resistance training. Body composition was measured by DXA at baseline, immediately after the wash-in, and at the end.

After seven days, before any training had begun, the creatine group had gained 0.51kg more lean body mass than controls (p=0.03), and among the women specifically, 0.59kg (p=0.04). Nothing had been built in a week. Creatine is stored inside muscle cells along with water, and a DXA scan counts that water as lean tissue, because lean tissue is defined as what is neither fat nor bone.

Then came the part that matters. Across the twelve weeks of training that followed, both groups gained two kilos of lean mass (p<0.0001), with no difference between them whatsoever (p=0.71). Among women the comparison gave p=0.10 and among men p=0.35. The authors attribute the wash-in gain to creatine's "short-term effects on lean body mass measurements" and suggest a maintenance dose above 5g a day might be needed to change growth itself.

Two limitations are worth stating. The control group received no creatine and no placebo, so participants knew which group they were in. And the standard deviations around those wash-in differences were more than three times the size of the differences themselves, meaning individual responses varied enormously around a modest average.

What the dose looks like it needs

A separate 2026 systematic review in the same journal pooled seven randomised, placebo-controlled trials of creatine in postmenopausal women — 608 participants, interventions running from twelve to 104 weeks, mean age around 62. Lean mass favoured creatine at a mean difference of 0.37kg (95% CI 0.05 to 0.69), and leg-press strength more clearly, at 7.5kg (2.2 to 12.8). Bone density was unchanged. Adverse events were mild and comparable with placebo, and kidney measures were unchanged.

Two details in that review deserve more attention than the headline. The benefits appeared where 5g a day or more was combined with resistance training, while trials using 3g a day or less without training showed no measurable effect at all. And the 95% prediction interval around the lean-mass result ran from −0.10 to +0.84, which means that although the pooled average was positive, a new trial of similar design could plausibly find nothing. Risk of bias was rated as mostly "some concerns", with one large pre-registered double-blind trial at low risk.

Who funds this research

Three different kinds of industry involvement run through the papers above, and they are not equivalent. The first is advisory relationships: an author of the postmenopausal review chairs a Creatine for Health scientific advisory board supported by AlzChem, a creatine manufacturer, and a co-author is chief executive of the society that publishes the journal, which takes occasional funding from companies selling creatine. The second is publication costs: AlzChem supported the remaining article processing charge for that same review. The third is trial funding, which is the most direct: the corresponding author of the 2025 Nutrients trial had received a creatine sponsorship from a supplement company, though for an earlier and separate study rather than this one.

None of that makes the findings wrong, and the disclosures are in the papers because the authors put them there. It is worth knowing the shape of it, though: much of the recent literature on creatine passes through a small number of people with ties to one manufacturer, and the analysis in this article reporting the least favourable result is the one with no such ties.

What This Actually Means

If you start creatine, expect the scale to move by roughly a kilo, expect most of that to happen in the first week or two, and expect it to be water held inside muscle rather than anything you have built or gained. Weighing yourself after a few days and drawing a conclusion is the single easiest mistake to make here, in either direction.

If you are taking creatine in the hope of more muscle, the useful implication is less comfortable. The best recent test of that question found that the early jump in measured lean mass did not translate into greater growth over three months of training at 5g a day. Strength improved more reliably than size in the pooled data, which is a reasonable thing to take it for.

And if the scale is the reason you are thinking of stopping, the fat question is settled as clearly as this literature settles anything: across 63 trials there was no significant change in fat mass. For a fuller account of what creatine does when training isn't part of the picture, our piece on whether creatine works if you don't exercise covers a 2026 trial in adults aged 45 to 65.

Frequently Asked Questions

Does creatine make you gain fat?

No. A 2026 meta-analysis of 63 trials found no statistically significant change in fat mass. Body fat percentage fell slightly, but that is what happens arithmetically when lean mass rises and fat does not.

How much weight does creatine add?

Less than most people expect. Pooled across trials the increase in body mass is small, and the authors attribute it mainly to lean mass. Individual responses vary widely around that average.

Is creatine weight gain water or muscle?

Early on, water. A 2025 trial found half a kilo of extra DXA-measured lean mass after seven days, before any training, which the authors put down to creatine's short-term effect on the measurement itself.

How much creatine should I take?

The evidence in postmenopausal women points to 5g a day or more combined with resistance training. Three grams a day without training showed no measurable effect in those trials.

Does creatine work for women?

The trials suggest yes, with the same caveats. Women showed the clearest early rise in measured lean mass in the 2025 trial, and the postmenopausal review found small gains in lean mass and clearer gains in leg strength.

The Bottom Line

Creatine raises body weight by a small amount, mostly in the first week or two, and the evidence that it does not raise body fat is about as consistent as this field gets. What it does not reliably do, at 5g a day over three months, is produce more muscle than training produces on its own — and the early rise in lean mass that looks like proof of the opposite is water being counted as tissue by the scan. That makes creatine a reasonable thing to take for strength, a poor thing to judge by the scale, and a supplement whose most-quoted number is the one that means least.

This article is for general information and is not medical advice. If you have a kidney condition or any concern about a supplement you are taking, speak to your GP.

Sources

• Wang H, et al. Resistance training combined with creatine supplementation: a three-level meta-analysis of multidimensional outcomes from strength enhancement to body composition remodeling. Journal of the International Society of Sports Nutrition, 2026. https://pubmed.ncbi.nlm.nih.gov/42765482/
• Desai I, et al. The Effect of Creatine Supplementation on Lean Body Mass with and Without Resistance Training. Nutrients, 2025. https://pubmed.ncbi.nlm.nih.gov/40292479/
• Naddafha S, et al. Creatine monohydrate for lean mass, strength, and bone density in postmenopausal women: a systematic review and meta-analysis. Journal of the International Society of Sports Nutrition, 2026. https://pubmed.ncbi.nlm.nih.gov/42141930/
• Chun J, et al. Effects of creatine supplementation with and without exercise and diet intervention on body composition, cognitive function, and markers of health in middle-aged and older adults. Journal of the International Society of Sports Nutrition, 2026. https://pubmed.ncbi.nlm.nih.gov/42578920/