Taking creatine supplements may help your muscles store more glycogen, which is like a sugar reservoir, and since glycogen holds onto water, your muscles end up holding more water too.
Evidence from Studies
Supporting (1)
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Changes in Human Muscle Transverse Relaxation Following Short‐Term Creatine Supplementation
The study shows that taking creatine increases water inside muscle cells, which supports part of the claim. But it doesn’t prove that this happens because of glycogen or GLUT4.
Contradicting (3)
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Creatine supplementation increases glycogen storage but not GLUT-4 expression in human skeletal muscle.
The study shows creatine increases muscle glycogen, which could hold more water, but it proves this isn’t because of GLUT4, which the claim says is the reason.
Creatine supplementation does not affect human skeletal muscle glycogen content in the absence of prior exercise.
The study tested whether taking creatine increases muscle glycogen, but found it didn’t — unlike carbs, which did. So, creatine alone doesn’t seem to boost glycogen or the water that comes with it.
The study shows creatine helps muscles store more glycogen after exercise, but it found no evidence that it works by increasing the GLUT4 protein or by making muscles hold more water.
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.