Does Creatine Make You Gain Weight? Creatine Side Effects and Myths for Runners

Every runner who has considered creatine has heard the same list. It makes you fat. It wrecks your kidneys. It makes your hair fall out. It dehydrates you and gives you cramp. It is basically a steroid.

Almost none of it survives contact with the evidence. Here are the seven objections runners actually raise, with what the research says — including the two that are partly true.

1. "It will make me gain weight"

Partly true, and the most important one to understand.

Creatine draws water into muscle cells. Most people gain around 1–2kg in the first two to four weeks. For a 70kg runner that is roughly 1.5–3% of body mass, and body mass genuinely matters over a marathon.

Three things to hold alongside that:

• It is intracellular water, not fat. The water sits inside the working muscle. The expert review of creatine misconceptions published in the Journal of the International Society of Sports Nutrition examined both the water-retention and the fat-mass questions directly (Antonio et al., 2021). Creatine does not add fat mass.
• It plateaus. You do not keep gaining. It settles once your stores are saturated.
• You already accept this trade. Carb loading before a marathon stores glycogen with water and adds mass too. Runners do it deliberately because the stored fuel is worth more than the kilogram.

Practical answer: start creatine at the beginning of a training block, not two weeks out from a goal race. By race day the change has settled and you have had three months of better training.

2. "It damages your kidneys"

Not supported in healthy people.

This myth has a specific origin: creatine supplementation raises blood creatinine, and creatinine is what doctors measure to estimate kidney function. So a saturated creatine user can show a raised creatinine reading without anything being wrong with their kidneys. It is a measurement artefact, not damage.

Kidney function has been one of the most examined questions in the creatine literature and is addressed directly in the misconceptions review (Antonio et al., 2021). The ISSN position stand concluded that short and long-term supplementation — up to 30g per day for five years — is safe and well tolerated in healthy individuals and in a range of patient populations (Kreider et al., 2017).

The genuine caveat: if you have existing kidney disease, speak to your GP before taking creatine. And if you are having bloods done, tell whoever is interpreting them that you supplement — it saves an unnecessary scare.

3. "It causes hair loss"

One small study, endlessly repeated.

The entire basis for this claim is a single 2009 study in twenty rugby players that reported a rise in dihydrotestosterone (DHT), a hormone associated with male pattern baldness. It did not measure hair loss. Nobody in the study lost hair. It has not been consistently replicated.

The misconceptions review addressed the hair-loss question specifically (Antonio et al., 2021), and the honest summary is: one hormonal marker, in one small study, in one sport, with no measurement of the outcome everyone is worried about.

That is not the same as "proven safe forever", and we are not going to claim it is. It is a very thin evidential basis for a very confident internet claim.

4. "It dehydrates you and causes cramp"

Directly tested, and the opposite of what the evidence shows.

A systematic review with meta-analysis in the Journal of Athletic Training assessed ten randomised trials on creatine, exercise heat tolerance and hydration status. Its conclusion was unambiguous: no evidence supports the idea that creatine hinders the body's ability to dissipate heat or negatively affects body fluid balance, including in controlled trials of athletes exercising in the heat (Lopez et al., 2009).

Some research has pointed the other way — that greater intracellular water may actually help with heat tolerance.

The sensible qualification: creatine increases your cellular water demand, and distance runners lose sodium in sweat. Neither of those is a creatine side effect; both are reasons to take hydration and electrolytes seriously. That is why Daily Hydrate & Perform pairs 5g of creatine monohydrate with 500mg of sodium plus potassium and magnesium rather than selling creatine on its own.

5. "It's basically a steroid"

No. Different molecule, different mechanism, different legal status.

Creatine is an amino acid derivative your body already synthesises and that you eat in red meat and fish. Anabolic steroids are synthetic derivatives of testosterone that act on hormone receptors. The two have nothing in common except that some people in gyms take both.

Creatine is not on the WADA prohibited list. It is legal in every sport.

The real anti-doping risk is contamination, not creatine. Poorly controlled supplement manufacturing is a documented route to positive tests, and strict liability means "it was in my supplement" is not a defence. Buy batch-tested product — you can check any supplement on the Cologne List® product database. Every RunnerVits product is independently Cologne List® tested for banned substances.

6. "It's a gym supplement — it does nothing for endurance"

The evidence has moved on from this.

Three findings are directly relevant to distance runners:

• Glycogen. A controlled trial with muscle biopsies found creatine plus a high-carbohydrate diet produced greater muscle glycogen supercompensation than carbohydrate alone, visible within 24 hours of exhaustive exercise (Roberts et al., Amino Acids, 2016). That is directly relevant to carb loading and to recovery between sessions.
• Protein breakdown after endurance running. Athletes running identical 60-minute endurance sessions before and after 15 days of creatine showed lower post-exercise lactate and reduced markers of protein degradation (Tang et al., Eur J Nutr, 2013).
• Training load tolerance. The ISSN position stand explicitly lists helping athletes tolerate heavy training loads among creatine's effects (Kreider et al., 2017).

What is not claimed: creatine does not improve VO2 max or running economy. Its value to a distance runner is in the training that produces the race, not in the race itself.

7. "It's only for men"

Wrong, and the reason is marketing rather than physiology.

The ISSN position stand on the female athlete concluded that caffeine, iron and creatine have the most evidence for use in women, that both iron and creatine are highly efficacious for female athletes, and recommended 3–5g of creatine per day (Sims et al., 2023). Higher doses have been studied in postmenopausal women for bone, mental health and muscle function.

The side effects that are actually common

To be complete, the ones you might genuinely experience:

• GI discomfort. Usually from taking too much at once, or from a 20g/day loading phase. Steady 5g a day resolves nearly all of it.
• The water weight. Covered above. Real, expected, plateaus.
• Nothing else, at recommended doses, in healthy adults. That is not a marketing line — it is what a literature of more than 500 peer-reviewed studies supports.

And if you stop?

Worth knowing, because it removes the fear of a permanent change: the effect is reversible. Muscle creatine stores return to baseline over a few weeks once you stop, and any associated water weight goes with them. There is nothing to work around if you decide it is not for you.

Who genuinely should not take it

• Anyone with existing kidney disease, without speaking to their GP first
• Anyone pregnant or breastfeeding, without medical advice
• Under-18s, other than under professional guidance
• Anyone taking medication that affects kidney function, without checking

Where that leaves you

Of seven common objections, five are not supported by evidence, one (hair loss) rests on a single small study that did not measure hair, and one (weight gain) is real, predictable, plateaus, and is planned around by starting at the beginning of a block.

Daily Hydrate & Perform gives you 5g creatine monohydrate, 5g L-glutamine and a sodium, potassium and magnesium blend in one citrus-flavoured scoop — made in the UK, no unnecessary fillers, independently Cologne List® tested.

Shop Daily Hydrate & Perform →

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Further reading

• Cologne List® product database — search which supplements have been batch-tested for banned substances at the German Sport University Cologne.
• British Dietetic Association Food Fact Sheets — independent, dietitian-written guidance on nutrients and supplements.
• SENR Registrant Directory — find a registered sport and exercise nutritionist if you want individual advice.

References

1. Antonio J et al. Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? J Int Soc Sports Nutr. 2021;18(1):13. https://doi.org/10.1186/s12970-021-00412-w
2. Kreider RB et al. J Int Soc Sports Nutr. 2017;14:18. https://doi.org/10.1186/s12970-017-0173-z
3. Lopez RM et al. J Athl Train. 2009;44(2):215–23. https://doi.org/10.4085/1062-6050-44.2.215
4. Roberts PA et al. Amino Acids. 2016;48(8):1831–42. https://doi.org/10.1007/s00726-016-2252-x
5. Tang FC et al. Eur J Nutr. 2014;53(1):61–71. https://doi.org/10.1007/s00394-013-0498-6
6. Sims ST et al. J Int Soc Sports Nutr. 2023;20(1):2204066. https://doi.org/10.1080/15502783.2023.2204066

Study references retrieved via PubMed. This article is for general information and is not medical advice. Food supplements are not a substitute for a varied diet and healthy lifestyle.