"Bigger" covers three different things, and they move on different timetables: the scale, the tape measure and the scan. Creatine is known to move the scale. Whether it moves the tape and the scan — and whether anyone would see it in a mirror — is a narrower question, and the studies that measured it answer it less neatly than either the marketing or the warnings suggest.
This page stays on the appearance-of-size question. The scale is on does creatine make you gain weight, photographs on creatine before and after, and the face on creatine face.
Why muscle could look fuller in days
Creatine is stored in muscle mostly as phosphocreatine, and the stored molecules are osmotically active: they draw water into the muscle cell. A high starting intake raises muscle creatine by roughly a fifth within about a week, and total body water and body weight rise with it — the timeline is on creatine loading phase. Body-water trials using isotope dilution show the water goes mainly inside cells, with one 2023 trial in women finding extracellular fluid also rose in the luteal phase (creatine face has the table).
Water inside a muscle cell is still inside the muscle. If enough of it arrives, a muscle should measure larger. Three studies scanned or measured limbs after a few days to find out.
Three short-term measurements, three answers
| Study | Who | Creatine | Measure | Result |
|---|---|---|---|---|
| Ziegenfuss et al. 2002 | 20 NCAA Division I athletes, 10 men and 10 women | 0.35 g/kg fat-free mass a day, 3 days | MRI, 10 slices of both thighs | Body mass +0.9 kg; thigh volume +6.6% in five of six creatine subjects scanned |
| Kamber et al. 1999 | 10 trained men, crossover | 20 g a day, 5 days | MRI of lower-limb muscle | Body weight 76.5 → 77.9 kg; no increase in muscle volume in the region imaged |
| Kambis and Pizzedaz 2003 | 22 college-age women | 0.5 g/kg fat-free mass a day, 5 days, no resistance exercise | Tape measure, skinfold, fat-free mass | No change in mid-thigh circumference, thigh skinfold, fat-free mass or body weight; quadriceps power improved |
The figures are as each trial reports them; none of them is a recommendation.
The disagreement is not hard to explain, though none of the three papers explains it. The positive MRI result came from six scanned subjects; the negative one imaged a limited volume of the lower limb in ten men; the women's study used a tape measure, which picks up centimetres, not the few per cent the MRI study found. What the three together establish is that a short loading period can enlarge a thigh measurably, that it does not reliably do so, and that nobody has repeated the positive MRI result in a larger group.
Over months: a very small extra gain
The best summary of longer trials is the 2023 meta-analysis by Burke and colleagues in Nutrients, which pooled only randomised trials of at least six weeks that imaged muscle directly — MRI, CT or ultrasound — in people doing resistance training with creatine or placebo. Across 10 trials:
- the pooled standardised effect was 0.11 (95% credible interval −0.02 to 0.25), which the authors call "a very small effect" favouring creatine;
- multivariate estimates for upper- and lower-body muscle thickness were 0.10 to 0.16 cm more than training with placebo;
- the benefit looked slightly larger in younger than in older adults.
The paper's conflict-of-interest statement lists advisory roles with supplement and creatine manufacturers among several authors. The size of the effect is consistent with the lean-mass meta-analyses on creatine for muscle growth: real, and small next to what the training itself produces.
Whether 1 to 1.6 millimetres of extra muscle thickness is visible is a question no trial has asked. None of the imaging trials measured appearance — photographs, ratings by observers, or self-assessment.
The glute question
A large share of the searches behind this page are about one muscle: "does creatine make your butt bigger" is searched more than "does creatine make you look bigger" itself. The literature has nothing on it.
A PubMed search run on 2026-10-20 for creatine supplementation with gluteus, gluteal, buttock or buttocks in the title or abstract returned 10 records. None measured the glutes of people taking creatine. One measured the gluteus medius of horses — aerobic training, but not creatine, altered it (D'Angelis et al., J Anim Sci 2005); the others are animal feed studies, antioxidant trials or a surgical case report that mention the words incidentally. The lower-body imaging in the human trials was of the thigh.
So the honest answer is that the glute effect of creatine is unmeasured. The thigh data suggest that any extra gain with training would be small, but the glutes have not been scanned, and a different muscle is not a substitute measurement. The longer trials in women are collected on creatine for women.
What is not established
- Whether the short-term water shift is visible. The positive MRI result is one small study; the visible effect has never been tested.
- Any glute-specific effect. No human study has measured it.
- Whether a visible change persists after stopping. The water leaves as muscle creatine falls back over weeks; what happens on stopping is on stopping creatine.
Sources
All opened 2026-10-20.
- Ziegenfuss TN et al. "Effect of creatine loading on anaerobic performance and skeletal muscle volume in NCAA Division I athletes." Nutrition 2002;18(5):397–402. PMID 11985944
- Kamber M et al. "Creatine supplementation — part I: performance, clinical chemistry, and muscle volume." Med Sci Sports Exerc 1999;31(12):1763–9. PMID 10613426
- Kambis KW, Pizzedaz SK. "Short-term creatine supplementation improves maximum quadriceps contraction in women." Int J Sport Nutr Exerc Metab 2003;13(1):87–96. PMID 12660408
- Burke R et al. "The Effects of Creatine Supplementation Combined with Resistance Training on Regional Measures of Muscle Hypertrophy: A Systematic Review with Meta-Analysis." Nutrients 2023;15(9):2116. PMID 37432300
- D'Angelis FH et al. "Aerobic training, but not creatine supplementation, alters the gluteus medius muscle." J Anim Sci 2005. PMID 15705754
- PubMed census: creatine AND (gluteus OR gluteal OR buttock OR buttocks) AND supplement*, title/abstract, 10 records, run 2026-10-20.