Creatine pulls water into your cells, making them swell a bit, and that swelling is how it helps your body work better.
Evidence from Studies
Supporting (2)
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Effect of Creatine Supplementation on Body Composition and Malnutrition-Inflammation Score in Hemodialysis Patients: An Exploratory 1-Year, Balanced, Double-Blind Design
The study found that taking creatine increased the amount of water inside people's cells, which may help explain how it improves muscle mass.
Creatine monohydrate supplementation strategies on body composition and water distribution in female recreational athletes
The study found that taking creatine led to more water moving into muscle cells, which supports the idea that creatine works by making cells swell with water.
Contradicting (2)
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Effects of acute creatine monohydrate supplementation on leucine kinetics and mixed-muscle protein synthesis.
The study looked at whether creatine helps build muscle by affecting protein, but it didn’t test if creatine works by pulling water into cells. Since it didn’t measure water or swelling, it doesn’t support that idea—and found no muscle growth, which makes the claim seem less likely.
Creatine Supplementation Does Not Influence the Ratio Between Intracellular Water and Skeletal Muscle Mass in Resistance-Trained Men.
The study found that when people take creatine and build muscle, the amount of water inside their cells goes up, but only in step with muscle growth—not because water is pulling in first to swell the cells.
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.