Few topics in sports nutrition cause as much confusion as creatine. Some people avoid it because they think it damages the kidneys, some take it without knowing why, and some give up after a few weeks because they didn't feel any different. The problem isn't creatine — it's that most of what circulates about it doesn't come from where it should. Creatine is, by a wide margin, the most researched supplement in the history of exercise science, backed by decades of studies and thousands of trial participants. It's worth separating what the research actually shows from what's just gym folklore.
What creatine actually does inside the muscle
Creatine is a molecule your body already produces, mainly in the liver and kidneys, and also gets from meat and fish. About 95% of it is stored in skeletal muscle as phosphocreatine, acting as a fast-access energy reserve. When you do a short, intense effort — a heavy squat set, a sprint, an explosive lift — your body taps the ATP-phosphocreatine system to regenerate energy almost instantly, before glycolysis or aerobic respiration even kick in.
Supplementing with creatine raises the muscle's phosphocreatine stores beyond what diet alone can sustain. In practice, that means more available energy for an extra rep, a slightly heavier load, or a faster sprint, set after set. The effect doesn't show up after a single workout: it builds over weeks, as muscle stores saturate and your body adapts to the training volume that extra energy lets you sustain.
What the research shows about strength and muscle mass
A systematic review with meta-analysis published in 2024 pooled 23 studies and 509 participants under age 50 to compare creatine combined with resistance training against a placebo paired with the same training. The result: the creatine group gained, on average, 4.43 kg more upper-body strength and 11.35 kg more lower-body strength than the placebo group over the same training period. That's not creatine acting alone — it's creatine stacked on top of the training stimulus, which is exactly how it works: it doesn't build strength without training behind it.
Source: PubMed
The same pattern shows up in reviews covering other populations, including older adults and people in rehabilitation: the strength and lean-mass gains disappear when you compare creatine alone against training without supplementation, but they show up consistently when creatine is paired with ongoing resistance training. In other words, it amplifies a stimulus that already needs to exist — it doesn't replace it — and the effect depends on consistency, not a single dose before a big session.
Do you actually need a loading phase?
There are two ways to start taking creatine. The first is a loading phase: roughly 20 grams a day, split into four doses, for five to seven days, followed by a maintenance dose. The second is skipping straight to the maintenance dose with no loading at all. Both paths reach the same saturated muscle stores — the only difference is time: loading speeds things up to a matter of days, while starting directly at the maintenance dose takes three to four weeks to produce the same effect.
Source: Examine.com
For most people, skipping the loading phase and taking 3 to 5 grams a day, every day, is the simplest option and the one that causes the least digestive discomfort. Loading only makes sense when you need the fast effect, like the week before a competition. Outside of that, it's an optional step that adds complexity without delivering any extra benefit in the long run.
- Choose creatine monohydrate: it's the most studied form and the cheapest, with no evidence that pricier forms work any better.
- Take 3 to 5 grams a day, every day — including rest days, since what matters is keeping the muscle store saturated.
- Mix it into water, juice, or whatever shake you already drink; timing around your workout doesn't matter, daily consistency does.
- Give it at least three to four weeks before judging whether it's working, especially if you skipped the loading phase.
- Drink water normally throughout the day; there's no need to overhydrate because of creatine.
Side effects and the kidney myth
The most common fear around creatine is that it strains the kidneys. That worry comes from a real but avoidable mix-up: creatine converts into creatinine, and creatinine is the marker blood tests use to assess kidney function. Taking creatine raises blood creatinine, which can alarm anyone reading a lab result without context — but that reflects the supplement's normal metabolism, not kidney damage.
At recommended doses, creatine's safety profile is well established: the side effects reported most often, mainly at the higher doses used for performance, are cramping, gastrointestinal discomfort, water retention, and dizziness — not kidney problems in healthy people. That doesn't apply to anyone with pre-existing kidney disease, who should check with a doctor before supplementing with anything.
Source: NSCA
Fitting creatine into a routine you'll actually keep
The most studied supplement in the world is useless if it ends up forgotten in a cabinet after week two. Since creatine depends on daily consistency to keep the muscle store saturated, it pairs well with any habit you already have for tracking your training — if you already log your workouts to keep your streak going, it's worth marking whether you took your dose too, at least until it becomes automatic. It's not about adding another task; it's about tying a new habit to one you already keep.
Creatine doesn't replace training, doesn't replace sleep, and doesn't replace consistency — it amplifies what you're already doing right.
It's also worth remembering that not everyone starts from the same baseline. People who eat a lot of red meat and fish already maintain relatively higher muscle creatine stores through diet; vegetarians and vegans tend to start from a lower baseline and, because of that, often notice a proportionally bigger difference when they supplement. In neither case is creatine mandatory — it's an optional tool that helps you squeeze a bit more out of training you're already doing, not a requirement for progress.