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What Is Creatine? Simply Explained
Creatine is a nitrogenous organic acid produced endogenously in the liver, kidneys, and pancreas from amino acids (arginine, glycine, and methionine), and is also obtained exogenously through diet, primarily from meat and fish. It plays a critical role in the phosphocreatine energy system.
4 questions. Published Mar 11, 2026. Updated Oct 19, 2026. By AI Fit Hub.
Definition
Creatine
Creatine is a nitrogenous organic acid produced endogenously in the liver, kidneys, and pancreas from amino acids (arginine, glycine, and methionine), and is also obtained exogenously through diet, primarily from meat and fish. It plays a critical role in the phosphocreatine energy system.
Why it matters
It is one of the best-supported supplements for training. After a loading phase, performance in high-intensity and repeated efforts is generally 10 to 20% higher, depending on how much muscle phosphocreatine rises (Kreider 2017). The ISSN position stand also lists possible benefits for recovery, injury prevention and neuroprotection, with long-term use up to 30 g a day for five years judged safe in healthy people.
How it works
Creatine raises the muscle's store of phosphocreatine (PCr). During intense effort, ATP breaks down to ADP to release energy, and PCr donates its phosphate to rebuild ATP quickly, which supports short, maximal efforts. The fastest way to fill muscle stores is about 0.3 grams per kilogram of body weight a day (around 20 g in four doses) for 5 to 7 days, then 3 to 5 grams a day; taking 3 grams a day without loading fills them over about 28 days (Kreider 2017).
Example
An athlete initiating creatine supplementation for performance enhancement.
Athlete's Body Weight (BW)
75 kg
Recommended Loading Dose
0.3 g/kg BW
Calculated Daily Loading Dose (75 kg * 0.3 g/kg)
22.5 g
Typical Maintenance Dose
3-5 g/day
For a 75 kg athlete, a creatine loading phase would involve consuming approximately 22.5 grams of creatine daily for 5-7 days. Following this, a maintenance dose of 3-5 grams per day would be sufficient to keep muscle creatine stores saturated and support continued performance benefits.
Key takeaways
Creatine is a natural compound for rapid energy production in muscles during high-intensity exercise.
After loading, it generally improves high-intensity and repeated-effort performance by 10 to 20% (Kreider 2017).
Load at about 0.3 g/kg a day for 5 to 7 days, or skip loading and take 3 g a day for about four weeks; then 3 to 5 g a day keeps stores full.
Questions people ask next
Is creatine safe, and does it have any side effects?
Creatine is one of the most extensively studied and safest supplements, particularly creatine monohydrate. Most research indicates it is safe for healthy individuals when used at recommended dosages. The most common side effect reported is mild gastrointestinal discomfort if taken in large single doses, or slight weight gain due to increased intracellular water retention, which is often desirable for performance. It does not cause kidney damage in healthy individuals, contrary to some myths, but those with pre-existing kidney conditions should consult a doctor.
What is the best type of creatine to take?
Creatine monohydrate is overwhelmingly considered the gold standard due to its extensive research, proven efficacy, safety profile, and cost-effectiveness. While other forms like creatine ethyl ester, buffered creatine, or creatine hydrochloride exist and claim superior absorption or fewer side effects, scientific evidence largely does not support these claims over monohydrate. For most users, creatine monohydrate remains the most effective and recommended choice to maximize muscle creatine stores and enhance performance.
When is the best time to take creatine?
Timing matters less than taking it every day, because the goal is to keep muscle stores full. Taking it with carbohydrate and protein increased creatine retention in a study cited by the ISSN (Kreider 2017), so a meal is a convenient time. Daily consistency is what counts over the weeks.
Does creatine cause weight gain, and is it fat or water?
Loading usually adds a little weight, mostly water: early studies reported short-term fluid retention of about 0.5 to 1.0 litres, roughly matching the weight gained (Kreider 2017). It is not fat. Over months, better training can also add lean mass. Antonio and colleagues' review addresses the water-retention and fat-mass questions directly.
Sources
- International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine , Journal of the International Society of Sports Nutrition (2017) — Kreider et al.
- Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? , Journal of the International Society of Sports Nutrition (2021) — Antonio et al.