Creatine monohydrate: the evidence for muscle, and beyond

Creatine monohydrate is the most evidence-backed supplement in sports nutrition, and the case for it now reaches beyond muscle. It works by topping up phosphocreatine, the cell's fastest way to regenerate ATP, the molecule that powers short bursts of effort. The strong evidence is for strength and lean mass when paired with training; the emerging evidence for cognition, mood and sleep deprivation is real but weaker. A simple 3 to 5 g daily is enough, loading is optional, you do not need to cycle, and the long-standing kidney scare is largely a misreading of a blood test.

How creatine actually works

Your muscles and brain run on ATP, but hold only enough for a few seconds of all-out work. When ATP releases energy it becomes ADP, which must be recharged almost instantly. The fastest recharger is phosphocreatine: it donates its phosphate to ADP and regenerates ATP in milliseconds, buying you more hard reps, another sprint, or a heavier lift. This store is small, and most people sit only 60 to 80% saturated, so supplementing tops up the tank. That is also why the clearest benefits appear in repeated short, intense efforts.¹ You make about a gram a day and get another from meat and fish, so vegetarians and vegans start with less and often respond more.⁷ Our health library and the stack builder can show where it fits a wider routine.

The strong evidence: strength and lean mass

This is where the data are genuinely robust. A 2024 systematic review and meta-analysis found that adding creatine to resistance training increased lean body mass by about 1.14 kg (95% CI 0.69 to 1.59) over training alone, with a small reduction in fat mass.² The classic Branch meta-analysis of 100 studies put the performance effect size at around 0.24 for short, high-intensity (ATP-phosphocreatine) work, the exact domain the mechanism predicts.⁴ Effects on a single one-rep max or on endurance are smaller: creatine helps you train harder over weeks rather than transforming one effort.

The emerging evidence: brain, mood and sleep

The brain uses the same phosphocreatine system, so the hypothesis is reasonable. A 2024 meta-analysis of 16 randomised trials (492 adults) reported a small, significant benefit for memory (standardised mean difference 0.31, 95% CI 0.18 to 0.44), graded as moderate-certainty.⁵ But honesty matters here: in November 2024 the European Food Safety Authority rejected a health claim for creatine and cognition, judging that methodological flaws in the trials meant no firm conclusion could be drawn.⁶ Both things are true at once: a suggestive signal, and a regulator unconvinced the proof is solid.

Two specific situations look more promising. In sleep deprivation, a 2024 study gave a single very large dose (0.35 g/kg, over 20 g) during 21 hours awake and saw improved processing speed and memory alongside changes in brain energy markers.⁸ That is a one-off experimental dose, not a daily recommendation. For mood, a 2012 trial added 5 g/day of creatine or placebo to the antidepressant escitalopram in 52 women with depression; the creatine group improved faster and further on depression scores.⁹ Using creatine to influence mood or cognition is an off-label, unlicensed use and should be discussed with a clinician, not self-prescribed in place of treatment.

Dosing: simple, and no need to cycle

The protocol is dull on purpose. Take 3 to 5 g of creatine monohydrate every day, with or without food, whenever you will remember; that saturates muscle stores in three to four weeks. For a faster effect, an optional loading phase of about 20 g/day split into four doses for 5 to 7 days reaches saturation in under a week before you drop to maintenance, though it sometimes causes mild bloating.¹ You do not need to cycle: once stores are full, daily intake maintains them. Plain monohydrate is the most studied and cheapest form, and the fancier salts and "buffered" versions have not been shown to beat it.¹

Safety and the kidney myth

Creatine has one of the strongest safety records of any supplement: the sports-nutrition position stand finds no convincing evidence that use up to 30 g/day for five years harms the kidneys, liver or other organs in healthy people.¹ The persistent worry is a measurement quirk. Creatine breaks down to creatinine, the very waste product used to estimate kidney function, so supplementing can nudge blood creatinine up without changing actual filtration (eGFR). A clinician unaware you take creatine may misread that as failing kidneys when nothing is wrong.³

Who benefits most

If you do regular resistance or high-intensity training and want more out of it, creatine is close to a default choice. Older adults are a strong case: paired with resistance training, doses around 0.1 g/kg/day improve lean mass and lower-body strength, which matters for preserving independence.¹⁰ Vegetarians and vegans, who get little from diet, may notice more.⁷ The honest exception is the inactive person hoping for a cognitive lift: the evidence there is still soft, so set expectations accordingly. Our insights pieces apply the same evidence-first lens elsewhere.

This article is educational and does not constitute medical advice, diagnosis, or a treatment recommendation. Medication uses described as “off-label” are not licensed for that purpose in the UK and should only be considered under qualified clinical supervision. Always speak to your GP, pharmacist, or a registered specialist before starting, stopping, or changing any treatment. If you have severe or alarm symptoms - unintentional weight loss, blood in your stool, difficulty swallowing, persistent vomiting, a fever, or severe pain - seek urgent medical care.