When your muscles store glycogen, it holds onto water—about 3 to 4 grams of water for every gram of glycogen. If glycogen runs low, cells get less hydrated, and that makes creatine less effective at pulling water into cells.
Evidence from Studies
Supporting (1)
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Relationship between muscle water and glycogen recovery after prolonged exercise in the heat in humans
The study shows that when muscles store glycogen, they also store water—about 3 grams of water for every gram of glycogen—just like the claim says.
Contradicting (2)
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Muscle glycogen depletion does not alter segmental extracellular and intracellular water distribution measured using bioimpedance spectroscopy.
The study found that even when muscle glycogen was low, the amount of water inside and outside muscle cells didn’t change, which goes against the idea that low glycogen dries out cells and makes creatine less effective.
The study found that creatine helped muscles store more glycogen after exercise, but it didn’t change muscle water levels or signs of cell swelling, which means water wasn’t being pulled in as the claim suggests.
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.