You've probably heard it at the gym: "Take your creatine with grape juice, or it won't do anything." That advice has been around since the '90s. And if you fast, it leaves you with a pretty silly choice: break your fast with a big glass of sugar, or take your creatine "for nothing."
It's a false choice. The advice comes from real research. People just walked away with half of it.
Where the grape juice thing started
In 1996, a British team led by Green gave volunteers creatine, with or without a big hit of sugar: 93 g of simple sugars for every 5 g serving of creatine. For reference, that's more sugar than two cans of soda. The creatine-plus-sugar group stored noticeably more creatine in their muscles.
The same group then went looking for the reason. It was insulin. The catch is that insulin only really helps when it climbs very high, around 100 mU/L according to the measurements they published in 1998. Getting there takes roughly 100 g of carbs at once, or a mix of about 50 g of protein and 50 g of carbs (their 2000 follow-up). So we're talking about a real meal, not a sip.
And here's the part that got lost: in that 1996 study, the group taking creatine without sugar also raised their muscle stores. Sugar speeds things up. It isn't what opens the door.
How creatine actually gets into muscle
Creatine can't just slip through the wall of your cells on its own. It needs a transporter, basically a dedicated turnstile. The scientific name gives it away: the "sodium- and chloride-dependent creatine transporter."
In 2022, a research team (Farr and colleagues) took a close look at that turnstile. Every time it turns, it brings in one creatine molecule along with two sodium ions and one chloride ion. When they took the sodium away from around the cells, the transporter simply stopped. Older work on isolated muscle in the lab had reached the same conclusion: creatine uptake depended on sodium, not on insulin.
What keeps the turnstile spinning is the sodium difference between the outside and the inside of the cell. That difference is maintained around the clock by the sodium-potassium pump, which itself runs on magnesium-bound ATP. Sodium, potassium, magnesium. The same three minerals this whole series keeps coming back to. You couldn't make it up.
Time does the same job sugar does
Also in 1996, Hultman's team compared two ways of filling up the muscles. At 20 g a day for 6 days, muscle creatine went up by about 20%. At just 3 g a day, it took 28 days... to land on the same roughly 20% increase. Once they got there, 2 g a day was enough to hold it.
So sugar and loading phases buy you time. They don't buy you a better end result. If you fast, 3 to 5 g a day for a month gets you to the same place without touching your window.
A free boost: move
Back in 1992, Harris and colleagues noticed something interesting. In the same people, the leg that had been exercised took up more creatine than the leg that stayed at rest. Working muscle wants more. If you train fasted in the morning, you already have that lever, no insulin needed.
What we don't know yet
We'd rather be upfront about this. Nobody has tested in humans whether putting salt in the same glass as your creatine helps it get in better. The turnstile depends on the sodium around your cells, and your body keeps that level in a very tight range no matter how much salt you just swallowed. What we can say is that a faster who keeps losing sodium without replacing it (we covered that in the dizziness article) isn't setting things up ideally. That's a reasonable inference, not proof.
In practice
Take 3 to 5 g of creatine monohydrate a day, whenever it suits you. Showing up every day matters more than the time on the clock. You can take it with your electrolytes instead of with sugar. Train. Give it three or four weeks. And if you'd rather take it with your first meal, with some carbs and protein, that works too. It's a bonus, not a requirement.
We started Fasted Rebels because we were sick of half-truths that always end with someone selling you sugar. Here you get the whole picture, limits included. Feed the mission. Not the hunger.
This article is for information only and isn't a substitute for advice from a health professional.
Sources: Green AL et al., "Carbohydrate ingestion augments skeletal muscle creatine accumulation during creatine supplementation in humans," American Journal of Physiology, 1996; Steenge GR et al., "Stimulatory effect of insulin on creatine accumulation in human skeletal muscle," American Journal of Physiology, 1998; Steenge GR et al., "Protein- and carbohydrate-induced augmentation of whole body creatine retention in humans," Journal of Applied Physiology, 2000; Hultman E et al., "Muscle creatine loading in men," Journal of Applied Physiology, 1996; Harris RC et al., "Elevation of creatine in resting and exercised muscle of normal subjects by creatine supplementation," Clinical Science, 1992; Farr CV et al., "Cooperative Binding of Substrate and Ions Drives Forward Cycling of the Human Creatine Transporter-1," Frontiers in Physiology, 2022; Willott CA et al., "Creatine uptake in isolated soleus muscle: kinetics and dependence on sodium, but not on insulin," Acta Physiologica Scandinavica, 1999; Buford TW et al., "International Society of Sports Nutrition position stand: creatine supplementation and exercise," JISSN, 2007.
French version: Faut-il du sucre pour que ta créatine entre dans le muscle?
Also read, the fasting and electrolytes series: Why You're Cramping Mid-Fast · More Water While Fasted Isn't Always Safer · Why You Get Dizzy Standing Up Mid-Fast · Why Your Heart Pounds Mid-Fast · Why You Twitch and Sleep Like Garbage Mid-Fast · Why You Get a Headache Mid-Fast · Why Your Uric Acid Spikes Mid-Fast · Why You're Always Cold Mid-Fast · Why Your Creatinine Spikes on a Blood Test