Taking creatine for 5 days doesn’t boost muscle fuel stores in healthy young guys who aren’t working out or eating extra carbs — it needs more than just the supplement to make a difference.

Taking creatine for five days boosts creatine in muscles, but doesn’t change how much glycogen (energy) is used during intense cycling in healthy young guys — so more creatine alone doesn’t help save energy stores during endurance workouts if muscles weren’t already drained.

Taking creatine supplements the way some athletes do—starting with a big dose, then switching to a smaller one—might temporarily boost the sugar stored in your muscles, but that boost fades once you switch to the smaller daily dose.

If young, healthy guys take sugar supplements for 5 days, their muscles store more energy, but taking creatine doesn’t do the same — so sugar seems to fill up muscle fuel better than creatine when not working out.

Creatine might help your muscles store more glycogen, but only if you first do a workout that drains your energy stores — otherwise, it doesn’t do much for glycogen.

Taking 20 grams of creatine a day for five days boosts the amount of creatine in young men's muscles, even if they don’t work out or eat a lot of carbs.