Creatine for fighters

The claim under test

Two claims circulate about creatine in fight gyms, and they are both partly true, which is why the argument never ends.

The first is that creatine is the most reliably effective legal supplement an athlete can take. That one is supported at the level of consensus documents, not just individual trials. The 2018 IOC consensus statement on dietary supplements, written by a panel including Maughan, Burke, Phillips, Rawson and Geyer, states that of the large universe of products marketed to athletes, "only a few (including caffeine, creatine, specific buffering agents and nitrate) have good evidence of benefits." That is a short list, and creatine is on it.

The second is that creatine makes you heavier, and that a fighter cutting to a division cannot afford it. That one is also supported — by the same documents. The IOC panel's own entry on creatine ends with a caution about "a potential 1–2 kg BM increase after creatine loading (primarily as a result of water retention)" and names three groups it may be detrimental for: endurance athletes, athletes moving body mass against gravity, and athletes who "must achieve a specific BM target."

That last clause is the fighter. It is written into the consensus statement, and almost nobody in combat sports quotes it, because the supplement industry quotes the first half of the entry and the sceptics quote nothing at all.

The honest position is that both claims are true simultaneously and the interesting question is what to do about it — which is a question about when, not whether.

What the position stand actually says

The current ISSN position stand on creatine is Kreider et al., published in the Journal of the International Society of Sports Nutrition in June 2017. It is worth being precise about that date: a search will surface a 2007 stand as well, and there is no more recent one. Anyone citing a 2024 or 2025 ISSN creatine position stand is citing something that does not exist as of this writing.

The stand opens its formal position with this sentence:

Creatine monohydrate is the most effective ergogenic nutritional supplement currently available to athletes with the intent of increasing high-intensity exercise capacity and lean body mass during training.

Note what is inside it. Two outcomes are named — high-intensity capacity and lean body mass — and both are qualified by "during training." This is a training-adaptation claim, not a fight-night claim. Nothing in that sentence says anything about performance in a bout after a weight cut, and the stand does not attempt to.

On safety, the language is similarly specific:

There is no compelling scientific evidence that the short- or long-term use of creatine monohydrate (up to 30 g/day for 5 years) has any detrimental effects on otherwise healthy individuals or among clinical populations who may benefit from creatine supplementation.

And on side effects, one sentence that matters more to a fighter than any of the rest:

The only consistently reported side effect from creatine supplementation that has been described in the literature has been weight gain.

Read that as an athlete in a weight class and it stops being a footnote. The single reproducible adverse effect of the best-evidenced supplement in sport is the exact thing your sport penalises you for.

The 2025 ISSN position stand on combat sports specifically — Ricci et al. — lists creatine among the supplements that "have been shown to enhance performance and/or recovery during preparation phases, competition, and post-competition." It does not resolve the mass problem; it names creatine as useful and moves on. The tension is left for the athlete to manage.

The mechanism: why creatine shows up on a scale

Creatine raises scale weight because it is osmotically active and it is transported into muscle alongside sodium. The position stand puts the first part plainly: "Like carbohydrate, creatine monohydrate has osmotic properties that help retain a small amount of water."

The 2021 ISSN review by Antonio and colleagues gives the transport detail. Creatine is taken up from circulation by a sodium-dependent transporter, and because the transport involves sodium, water follows into the cell to maintain intracellular osmolality. Their assessment is that intracellular sodium concentration is unlikely to be dramatically affected, given how hard the sodium-potassium pumps work, but the water arrives regardless.

This is a different kind of water gain from the one fight-week protocols manipulate. Acute dehydration strategies move extracellular fluid — plasma volume, interstitial water, the compartments a sauna reaches. Creatine's water is intracellular, sitting inside the muscle fibre with the creatine that pulled it there. It is, in a physiological sense, more like the water bound to glycogen than the water in your blood.

That distinction has a practical consequence. Water inside a muscle cell is not water you can sweat off in an afternoon. The mass is real, it is on the scale, and it does not respond to the tools a fighter reaches for in the last twenty-four hours the way extracellular fluid does. If you are carrying it into fight week, you are carrying it.

The position stand also reports the volume involved: "initial studies reported that creatine loading promoted a short-term fluid retention (e.g., about 0.5 – 1.0 L) that was generally proportional to the acute weight gain observed." Half a litre to a litre. On the scale that is 0.5 to 1.0 kg, and it arrives inside a week.

How much mass, and under what conditions

Two figures circulate in the peer-reviewed literature, and they do not quite agree, which is itself worth knowing.

The ISSN group's 2021 review states: "The initial loading phase of creatine supplementation (i.e. 20 g/day for 5-7 days) typically results in a 1-3 kg increase in body mass, mostly attributable to net body water retention."

The IOC consensus statement gives the narrower band: "A potential 1–2 kg BM increase after creatine loading (primarily as a result of water retention) may be detrimental for endurance performance or in events where the BM must be moved against gravity (eg, high jump, pole vault) or where athletes must achieve a specific BM target."

Both figures carry the same three conditions and they must travel with them: after a loading protocol, at roughly 20 g/day for 5–7 days, and mostly water rather than tissue. A figure quoted without the loading protocol attached is describing a different intervention. Someone taking 3 g/day from the start is not the person these numbers were measured on.

Both are also ranges rather than points, and the range is wide relative to what a division tolerates. The distance between 1 kg and 3 kg is the distance between a nuisance and a missed weight. Neither document offers a way to predict which end of the range a given athlete lands on, and this is a genuine gap rather than an omission on their part — the determinants are not established.

Run the arithmetic as a scenario rather than a plan. Take an athlete contesting a 70.3 kg division. The 2025 ISSN combat-sports stand puts off-camp weight at 12% to 15% above the division requirement, which for that athlete is roughly 78.7 to 80.8 kg. A loading-phase gain of 1–3 kg on that body is 1.3% to 3.8% of body mass, appearing over five to seven days. For comparison, the same position stand describes acute fight-week water loss at optimally around 2–4% of body mass within 24 hours of the weigh-in, and attaches an explicit supervision requirement to that range in the same sentence. In other words: a loading phase can put on the order of an entire acute water phase back onto the scale, over a week, with no supervision involved and usually no one noticing until the number stops moving.

That is not an argument against creatine. It is an argument for knowing which week you are in.

What the combat-sport literature says

Until recently the honest answer to "what does the research say about creatine in combat athletes" was that almost nobody had asked as a distinct question.

That changed in 2025. Ashtary-Larky and colleagues published a narrative systematic review in the Journal of Dietary Supplements covering creatine supplementation in combat sport athletes, searching PubMed, Scopus, Web of Science and Google Scholar to March 2025. Nineteen studies met inclusion, across wrestling, judo, taekwondo and boxing.

Their reported findings, stated as they state them: creatine supplementation increased body mass, "especially during longer-term interventions (≥6 wk) or when combined with structured resistance training"; it increased measures of body mass and fat-free mass; muscular power and maximal strength improved significantly, "particularly in studies utilizing short-duration, high-intensity exercise protocols"; it did not influence measures of sport-specific endurance, recovery or fatigue; and no serious adverse effects were reported across the included studies.

Read that list against what a fighter wants. Power and maximal strength: improved. Sport-specific endurance, recovery, fatigue: no effect found. Body mass: up. That is a supplement that helps with the part of the sport that happens in bursts, does nothing measurable for the part that happens in round three, and costs you weight.

Whether that trade is worth making depends entirely on your division, your walking-around weight and your style, which is precisely why nobody can answer it for you in an article.

One of the included trials gives a sense of the scale of the underlying work. Sarshin et al., published in the Journal of the International Society of Sports Nutrition in 2021, randomised 40 trained taekwondo athletes (21 ± 1 years, 180.5 ± 7.3 cm, 72.7 ± 8.6 kg) across five groups for five days, testing creatine and sodium bicarbonate alone and together against placebo and control on a taekwondo-specific intermittent kick test. Peak and mean power increased with creatine. Forty athletes, five days. That is a respectable trial and it is also not the kind of evidence base that settles a question for an entire sport.

Loading and maintenance, as the papers describe them

Two protocols appear consistently in the literature. Reporting them is not prescribing them.

The ISSN position stand describes the fast route:

The quickest method of increasing muscle creatine stores may be to consume ~0.3 g/kg/day of creatine monohydrate for 5–7-days followed by 3–5 g/day thereafter to maintain elevated stores.

And the slow route, in the same paragraph:

Initially, ingesting smaller amounts of creatine monohydrate (e.g., 3–5 g/day) will increase muscle creatine stores over a 3–4 week period, however, the initial performance effects of this method of supplementation are less supported.

The IOC consensus gives the equivalent in absolute terms: a loading phase of roughly 20 g/day divided into four equal daily doses for 5–7 days, then a maintenance phase of 3–5 g/day as a single dose.

The 2021 ISSN review is the document that matters most to a weight-class athlete, because it addresses the choice between them directly. Its conclusion: "Smaller, daily dosages of creatine supplementation (3-5 g or 0.1 g/kg of body mass) are effective. Therefore, a creatine 'loading' phase is not required."

The comparison it rests on is the classic one. In the Hultman study the review cites, muscle creatine accumulation was similar — around a 20% increase — whether participants took 3 g/day for 28 days or 20 g/day for 6 days. The destination is the same. The loading protocol just gets there faster, and pulls the water in faster with it.

And then the sentence that is effectively written for fighters, though it never names them:

However, if an athlete or exercising individual is planning to ingest creatine over an extended period of time (> 30 days), or if avoiding potential weight gain which can sometimes occur during creatine 'loading', the creatine 'maintenance' strategy would be a viable option.

Avoiding the weight gain is named, in the ISSN group's own review, as a legitimate reason to skip loading. If you take one thing from the protocol literature, that is the sentence.

Does it need to be cycled?

No published evidence supports cycling, and the mechanism most often cited for it does not appear to occur.

The gym version of the rule is some variant of four weeks on, four weeks off, usually justified by a claim that continuous use suppresses the body's own creatine production or that the transporter downregulates and stops responding. Neither the position stand nor the 2021 review supports it.

What the position stand actually reports is the washout: "Research has shown that once creatine stores in the muscle are elevated, it generally takes 4–6 weeks for creatine stores to return to baseline." And on the suppression theory: "No evidence has suggested that muscle creatine levels fall below baseline after cessation of creatine supplementation; therefore, the potential for long-term suppression of endogenous creatine synthesis does not appear to occur."

Take those two sentences together and the cycling convention reads strangely. If it takes four to six weeks to wash out, then a four-week off-cycle is mostly spent with muscle stores still partly elevated — you have paid for the interruption without getting the reset it was supposed to deliver. And the reset was for a problem the literature says does not happen.

There is a version of cycling that does make sense for a fighter, and it is not the physiological one. It is the scheduling one: choosing to be off creatine during the descent to a division and back on it during the periods when carrying an extra kilogram costs you nothing. That is a weight-management decision, not a pharmacology one, and it should be described honestly as such rather than dressed up as a receptor-recovery protocol. Where that decision sits in a training year is the kind of thing fight camp planning is supposed to settle before it becomes urgent.

The kidney claim, and what the controlled work found

The kidney story is the most durable piece of misinformation attached to creatine, and its origin is traceable, which makes it a useful case study in how these things propagate.

The 2021 ISSN review calls it out directly: the notion that creatine leads to kidney damage is "perhaps second only to the myth that protein supplementation and high habitual protein intake causes kidney damage." Their account traces it to two things: a poor understanding of creatine and creatinine metabolism, and a single case study published in 1998.

The metabolism part is the important half, and it is a genuine measurement trap rather than folklore. Creatine and phosphocreatine degrade non-enzymatically to creatinine, which is excreted in urine, and blood creatinine is used clinically as a proxy marker of kidney function. But blood creatinine also tracks muscle mass and dietary creatine intake — so supplementing creatine, or simply eating a lot of meat, can raise the marker without anything happening to the kidney. As the review puts it, "transient increases in blood or urinary creatine or creatinine due to creatine supplementation are unlikely to reflect a decrease in kidney function."

The controlled data. In the review of creatine studies by Persky and Rawson that the ISSN paper cites, 12 studies found no increase in serum creatinine at all, 8 found an increase that remained inside the normal range, and only 2 found an increase above normal limits — and in one of those it was not different from the control group. The position stand adds the renal-function measurements directly: ingesting 20 g/day for 5 days, and up to 10 g/day from 10 months to 5 years, "had no effect on creatine clearance, glomerular filtration rate, tubular resorption, or glomerular membrane permeability compared to controls."

The 1998 case involved a young man who had had kidney disease for eight years and had been treated with an immunosuppressant for five, who then began taking creatine. His rising creatinine was read as deterioration. It was already known at the time that creatine ingestion raises creatinine independently of renal function.

The review's summary: "experimental and controlled research indicates that creatine supplementation, when ingested at recommended dosages, does not result in kidney damage and/or renal dysfunction in healthy individuals." The operative words are recommended dosages and healthy individuals. If you have existing renal disease, or you are taking anything nephrotoxic, this literature is not about you and the question goes to your physician.

The practical note for fighters, since combat sports involve a lot of pre-licence blood work: if you supplement creatine and a panel comes back with elevated creatinine, tell the physician reading it. It is a known interference, and it is better raised before someone starts investigating a kidney that is fine.

Cramping, heat and the fight-week worry

The concern that creatine's intracellular water impairs thermoregulation is physiologically coherent and it has been tested. It did not hold up.

The reasoning is straightforward enough: if creatine binds water inside the muscle cell, then under heavy sweating or heat stress that bound fluid is unavailable to the extracellular compartment, potentially driving dehydration, electrolyte disturbance and cramping. On that theory, the American College of Sports Medicine in the early 2000s recommended that people controlling their weight or training hard in the heat should avoid creatine. The 2021 ISSN review describes that recommendation as having been made "with limited data and based primarily on speculation."

Lopez and colleagues tested it systematically in the Journal of Athletic Training in 2009, screening 95 articles, identifying 15 that examined thermoregulation or hydration status, and selecting 10 randomised clinical trials meeting their criteria, all scoring 7 to 10 on the PEDro scale. Their conclusion: "No evidence supports the concept that creatine supplementation either hinders the body's ability to dissipate heat or negatively affects the athlete's body fluid balance."

The field data points the same way. In the study the ISSN review cites, 72 NCAA Division IA collegiate football players trained through a season in hot (27.3 ± 10.9 °C) and humid (54.2 ± 9.7%) conditions; 38 chose creatine at 0.3 g/kg/day for 5 days then 0.03 g/kg/day for 115 days, 34 took a sports-drink placebo. Creatine users had significantly less cramping, fewer heat illnesses and dehydration episodes, less muscle tightness, fewer muscle strains and fewer total injuries.

The ISSN review's summary is that experimental and clinical research does not validate the notion that creatine causes dehydration and muscle cramping. Two boundaries on that. First, none of this work was done on athletes undergoing a deliberate fight-week dehydration protocol — the question of how creatine interacts with an intentional acute water cut has not, as far as we can establish, been studied. Second, "does not cause cramping" is not the same claim as "protects you during a cut", and nothing here licenses the second one.

What the current WADA documents say

Creatine is not prohibited. We checked the primary documents rather than a summary of them, on 24 August 2026.

The 2026 WADA Prohibited List, the International Standard that came into effect on 1 January 2026, does not contain the word creatine. Not in S0 non-approved substances, not in S1 anabolic agents, not in S5 diuretics and masking agents, not anywhere in the document.

The 2026 Monitoring Program — the separate list of substances WADA watches under Article 4.5 of the Code without prohibiting them — does not contain it either. That list, in full, covers ecdysterone; GnRH analogues in females under 18; hypoxen; the in-competition stimulants bupropion, caffeine, nicotine, phenylephrine, phenylpropanolamine, pipradrol and synephrine; the narcotics codeine, dermorphin, dihydrocodeine, hydrocodone and tapentadol in competition and fentanyl and tramadol out of competition; and markers of semaglutide and tirzepatide. Creatine is absent.

We spell that out because a plausible-sounding claim circulates that creatine sits on the monitoring programme. It does not, and the document is four paragraphs long and freely downloadable, so the claim is checkable in about ninety seconds. Anyone repeating it has not opened it.

The 2017 position stand puts the underlying reason cleanly: "Creatine is found in high amounts in the food supply and therefore its use is not banned by any sport organization although some organizations prohibit provision of some types of dietary supplements to athletes by their teams." That last clause is a real distinction — a team or promotion declining to hand you a supplement is not the same as the substance being prohibited.

The contrast worth drawing is with what is on the list and what fighters are actually tempted by. S5 of the 2026 List covers all diuretics and masking agents, prohibited at all times, in and out of competition — every one of them a Specified Substance, and the class named explicitly includes furosemide, spironolactone, hydrochlorothiazide, torasemide and the rest. A weight-class athlete looking for a shortcut to the scale is looking at S5. Creatine is not in that conversation and never was. If banned-substance risk is the thing keeping you up, the supplements and nutrition material is the right place to start rather than this paragraph.

Two caveats on all of the above. Prohibited Lists are reissued annually, so verify against the list in force for your competition year, not this article. And your promotion or commission may run its own list that is stricter than WADA's — which brings us to the part that actually gets fighters suspended.

Contamination is the risk, not the molecule

Creatine being permitted tells you nothing about whether the tub in your kitchen is. Those are separate questions and the second one is where careers end.

The foundational measurement is Geyer et al., published in the International Journal of Sports Medicine in 2004. Between October 2000 and November 2001 the authors bought 634 non-hormonal nutritional supplements from 215 different suppliers across 13 countries, and analysed them by gas chromatography–mass spectrometry. Ninety- four of them — 14.8% — contained anabolic androgenic steroids not declared on the label. Reliable data could not be obtained for a further 66 samples, 10.4%. Positive rates by country of purchase ran to 25.8% in the Netherlands, 22.7% in Austria and 18.8% in both the UK and the USA.

That study is now old, and the IOC consensus statement is careful about what it can support: "It is difficult to gain a perspective of the true prevalence of supplement contamination. Although the original study reported that ~15% of more than 600 products acquired from around the world contained undeclared prohormones, this and other investigations rarely include a truly random sample of the supplements and sports foods used by athletes."

So the honest statement is not "15% of supplements are contaminated." It is that a systematic international survey found undeclared steroids in 14.8% of what it bought two decades ago, that the sampling was not random, and that reviews since suggest the problem persists without anyone having established a current rate.

What makes this lethal rather than merely annoying is strict liability. The IOC statement spells it out: even where ingestion was unintentional, "the rules of strict liability within the World Anti-Doping Code mean that an AAF will be recorded, and may mean the loss of medals won or records set, and financial sanctions as well as temporary or permanent suspension from competition." The label being wrong is not a defence.

The mitigation is third-party certification, and the IOC panel is careful about how much it buys you: "There can be no absolute guarantee that any product is entirely safe, but these schemes do help the athlete to manage the risk." Their instruction to athletes is a risk calculation, not a green light — "Athletes should do a careful risk analysis to see if the marginal gains would outweigh the risk of inadvertent doping due to contamination."

The UFC's own anti-doping programme has turned this into policy, and it is the single most concrete thing on this page for a professional. Its Approved Supplements page does not list products or ingredients at all. It lists certification marks — BSCG, Informed Choice, Informed Sport, HASTA, the Kölner Liste, NSF and TruShield Certified — and states: "The below supplements are the ONLY supplements approved under UFC ADP. These should be the only supplements you use. You will be protected should any issues result from using these supplements. If you use supplements other than those below, you are NOT protected." The programme is administered by Combat Sports Anti-Doping.

Read that carefully. Under that policy, the permitted status of creatine is irrelevant to whether you are covered. What determines coverage is whether the specific product carries one of those marks. An uncertified tub of a completely legal substance buys you nothing, and the price of finding out is your licence.

Where it sits against a camp and a weigh-in

Nothing in the literature tells a fighter when to take creatine relative to a weigh-in, because nobody has studied it. What the literature does give you is the shape of the problem, and the shape is fairly clear.

The mass arrives on the timescale of the loading protocol — 5 to 7 days at around 20 g/day, per both the ISSN stand and the IOC consensus — and it is intracellular water rather than tissue. It leaves on the timescale of the washout, which the position stand puts at 4 to 6 weeks for muscle stores to return to baseline. Those two timescales are wildly asymmetric, and the asymmetry is the entire practical point: the weight goes on in a week and comes off over more than a month.

Set that against the structure of a camp. The training that creatine is documented to support — high-intensity, repeated-effort work, resistance training, the adaptations the position stand describes as accruing "during training" — happens in the general and specific preparation blocks, weeks and months out. The scale problem happens in the last two weeks. Those are different parts of the calendar, and the asymmetry between a one-week onset and a six-week offset means the decision to stop has to be made a long way ahead of the decision to weigh.

The version of this that goes wrong is predictable: an athlete starts a loading protocol during fight camp because a training partner recommended it, gains 2 kg in a week that they read as "not losing weight", deepens the deficit to compensate, and arrives at fight week both heavier than planned and underfuelled. The mass was not fat and it was never going to respond to a bigger deficit. That failure mode is worth naming because it looks exactly like a stalled cut and is treated as one.

The general principle from how much weight can be cut before a fight applies here too: a plan built backwards from the weigh-in beats a plan built forwards from today. Creatine is a decision that belongs on that backwards plan, in a specific week, alongside every other input that moves the scale. Deciding it in isolation is how it becomes a surprise.

What no one can tell you is the right answer for your body. The 1–3 kg range is wide, the determinants of where in it you land are not established, and the only way to know is to have measured it on yourself in a period when the number does not matter. That is a conversation for a dietitian and a training block, not fight week.

What it does to your body-composition numbers

Creatine does not just move the scale. It moves the instruments you use to interpret the scale, which is a subtler problem and one that catches good coaches.

Bone and colleagues demonstrated this directly in Medicine & Science in Sports & Exercise in 2017. Eighteen well-trained male cyclists were assigned to creatine loading (20 g/day for 5 days, then 3 g/day maintenance) or placebo, with a crossover application of glycogen loading, and were measured by DXA, bioelectrical impedance spectroscopy and muscle biopsy. Creatine loading increased total body water by 1.4% ± 1.9%. Glycogen loading, with and without creatine, produced substantial increases in DXA estimates of lean body mass — 3.0% ± 0.7% and 2.0% ± 0.9% respectively — and the glycogen-depleting condition produced a decrease in leg lean mass of 1.4% ± 1.6%.

The authors' conclusion is the useful part: changes in muscle metabolites and water content alter DXA estimates of lean mass during periods when minimal change in actual muscle protein mass is likely.

In other words, a DXA scan run during a creatine loading phase or a carbohydrate load will report lean mass that has not been built. For a fighter tracking body composition through a camp — deciding whether the descent is costing muscle — that is a measurement artefact large enough to invert the conclusion.

The 2025 ISSN combat-sports position stand makes exactly this point for this population: DXA "is subject to confounding results from inter-assessment differences in hydration, glycogen and muscle creatine levels, all which can vary significantly in combat athletes." Combat athletes vary on all three of those axes more than almost any other group, which makes their body-composition data among the least trustworthy in sport unless the assessment conditions are tightly standardised.

The practical read: if you scan, scan under matched conditions, and treat any scan taken during a load — of creatine or of carbohydrate — as not comparable to the ones around it.

The populations the evidence does not cover

The creatine literature is large and the combat-sport slice of it is not, and the difference matters more than the total volume suggests.

Weight-class athletes managing a division. This is the striking gap. The 2021 ISSN review does not use the words "weight class", "combat", "wrestling", "judo" or "boxing" anywhere in its text. The 2017 position stand does not discuss weight-class management either. The 2025 combat-sport review found 19 studies, and by its own account they were designed to measure body mass, composition, strength, power, endurance, fatigue and cognition — not to answer whether and when a fighter should take creatine relative to a weigh-in. The question this article is about is, in evidence terms, mostly unanswered.

Women. The 2021 ISSN review has a section on creatine across the female lifespan and reports benefits, but the combat-sport trials in particular are dominated by male participants. The physiological variables that matter here — body composition, total body water as a fraction of mass, cycle effects on fluid balance — are not adjustable with a coefficient, and a 1–3 kg range derived largely from men is not automatically a 1–3 kg range in women.

Adolescents. The ISSN documents are unusually forward on this, stating that use in children and adolescents is acceptable where proper precautions and supervision are provided and that label advisories against under-18 use are likely unnecessary. That is their position and I report it as theirs. Note what it does not cover: adolescent athletes cutting weight. The intersection of a growing athlete, a weight class and a supplement that adds mass is not a studied population, and combining two under-evidenced things does not produce an evidenced one.

Anyone with renal disease. Explicitly outside the safety conclusions, which are stated for healthy individuals at recommended dosages.

Amateurs without support. Every protocol above was run with supervision and measurement. An amateur adding creatine three weeks out from a first competition, with no baseline and no scale history, is not replicating any of these studies.

What we could not verify

Stated plainly, because an article citing this precisely owes you its gaps:

• The current rate of supplement contamination. The 14.8% figure is from products purchased in 2000–01, and the IOC consensus explicitly warns that such surveys are not random samples. We found no current, randomised survey establishing a present-day rate, and we found no published study analysing creatine monohydrate products specifically for undeclared substances. Anyone quoting you a contamination rate for creatine in particular should be asked for the paper.
• The FDA GRAS position, in full. We verified the underlying documents: GRAS Notice GRN 000931 for creatine monohydrate was submitted on behalf of AlzChem Trostberg GmbH — a manufacturer, which is how the GRAS process works — received 5 March 2020, and FDA's response letter of 3 December 2020 states it has "no questions at this time" about AlzChem's conclusion. The same letter states it "is not an affirmation that creatine monohydrate is GRAS under 21 CFR 170.35", and the notified use was as a food ingredient at 1.12 g per serving in named product categories — not the 20 g/day supplement protocol. It is routinely cited as blanket FDA endorsement of creatine supplementation. It is narrower than that.
• Whether creatine interacts with an acute fight-week water cut. No study we located has tested creatine supplementation against a deliberate dehydration protocol. The heat-tolerance literature is about training and competing in heat, not about a sauna cut, and we will not extrapolate across that gap.
• Where in the 1–3 kg range a given athlete lands. Neither review offers predictors. The range is reported; the determinants are not.
• The Ashtary-Larky review's underlying trials. We read its abstract and its stated findings; the full text is behind a paywall and we have not audited the 19 included studies individually.
• Nothing here is specific to you. Not your division, your body composition, your medical history, your weigh-in format or your competition's anti-doping rules.

Sources

Sourced to

1. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine — Kreider RB et al., Journal of the International Society of Sports Nutrition, 13 June 2017;14:18. DOI 10.1186/s12970-017-0173-z, PMID 28615996
2. Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? — Antonio J, Candow DG, Forbes SC et al., Journal of the International Society of Sports Nutrition, 8 February 2021;18:13. DOI 10.1186/s12970-021-00412-w, PMID 33557850
3. IOC consensus statement: dietary supplements and the high-performance athlete — Maughan RJ, Burke LM, Dvorak J et al., British Journal of Sports Medicine, April 2018;52(7):439–455. DOI 10.1136/bjsports-2018-099027, PMID 29540367
4. International society of sports nutrition position stand: nutrition and weight cut strategies for mixed martial arts and other combat sports — Ricci AA et al., Journal of the International Society of Sports Nutrition, 2025;22(1):2467909. DOI 10.1080/15502783.2025.2467909, PMID 40059405
5. Creatine Supplementation in Combat Sport Athletes: A Narrative Systematic Review — Ashtary-Larky D, Candow DG, Forbes SC et al., Journal of Dietary Supplements, 2025;22(6):844–869. DOI 10.1080/19390211.2025.2539880, PMID 40755023
6. Manipulation of Muscle Creatine and Glycogen Changes Dual X-ray Absorptiometry Estimates of Body Composition — Bone JL, Ross ML, Tomcik KA et al., Medicine and Science in Sports and Exercise, May 2017;49(5):1029–1035. DOI 10.1249/MSS.0000000000001174, PMID 28410328
7. Does creatine supplementation hinder exercise heat tolerance or hydration status? A systematic review with meta-analyses — Lopez RM, Casa DJ, McDermott BP et al., Journal of Athletic Training, March 2009;44(2):215–223. DOI 10.4085/1062-6050-44.2.215, PMID 19295968
8. Analysis of non-hormonal nutritional supplements for anabolic-androgenic steroids — results of an international study — Geyer H, Parr MK, Mareck U et al., International Journal of Sports Medicine, February 2004;25(2):124–129. DOI 10.1055/s-2004-819955, PMID 14986195
9. Short-term co-ingestion of creatine and sodium bicarbonate improves anaerobic performance in trained taekwondo athletes — Sarshin A, Fallahi V, Forbes SC et al., Journal of the International Society of Sports Nutrition, 2021;18(1):10. DOI 10.1186/s12970-021-00407-7, PMID 33478522
10. The 2026 Prohibited List — International Standard — World Anti-Doping Agency, published September 2025, in effect 1 January 2026
11. The 2026 Monitoring Program — World Anti-Doping Agency, published September 2025, in effect 1 January 2026
12. UFC Anti-Doping Program — Approved Supplements — Ultimate Fighting Championship and Combat Sports Anti-Doping, checked 24 August 2026
13. Agency response letter, GRAS Notice No. GRN 000931 — creatine monohydrate — US Food and Drug Administration, Center for Food Safety and Applied Nutrition, letter dated 3 December 2020
14. GRAS Notice No. GRN 931, creatine monohydrate, submitted by AlzChem Trostberg GmbH — Center for Regulatory Services on behalf of AlzChem Trostberg GmbH, filed with the US Food and Drug Administration 5 March 2020

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