Creatine: The Supplement That Actually Works

The supplement aisle runs almost entirely on hope. Most of what is sold has either no good evidence or evidence that evaporates the moment a trial controls for diet and training. Creatine is the conspicuous exception. It has been studied for more than thirty years, in hundreds of trials, with a mechanism that is well understood and an effect that is large enough to notice. If you do any kind of strength or high-intensity training and you are going to take exactly one supplement, this is the one the evidence supports. This piece is about what it actually does — and about the surprising amount of folklore that has grown up around a molecule we understand quite well.

What creatine is

Creatine is a compound your body already makes and already stores. The liver, kidneys, and pancreas synthesise about a gram a day from three amino acids, and an omnivorous diet supplies roughly another gram or two from meat and fish. Most of it ends up in skeletal muscle, stored as phosphocreatine. When a muscle contracts hard, it burns through ATP — its immediate energy currency — within seconds, and phosphocreatine is the system that regenerates that ATP fastest. More phosphocreatine in the tank means more high-intensity work before the system runs dry.

The catch is that muscle stores are not normally full. A typical omnivore sits at roughly 60–80% of the muscle's storage capacity; vegetarians and vegans, who get almost no dietary creatine, sit lower still. Supplementation simply tops the tank up to its ceiling — and topping it up from food alone is impractical, because the creatine content of meat is modest and cooking degrades some of it.

What it actually does

The well-established effects are narrow and real. Creatine improves performance in short, hard, repeated efforts — sets in the weight room, sprints, jumps, the second and third bout of anything explosive. Across the literature it adds a few percent to strength and power output and lets you grind out an extra rep or two, which compounds over months into more training volume and therefore more muscle. That last part matters: a good deal of creatine's effect on size is indirect. It does not build muscle on its own; it lets you train slightly harder, and the training builds the muscle — which only translates into size if you are also eating enough protein to support it.

What it does not do is also worth stating plainly. It is not an endurance aid in any meaningful sense — for steady-state cardio the benefit is negligible, and the extra water weight can even be a small liability. It is not a fat burner. And it is not a stimulant; it does nothing acutely, which is why the timing obsession around it is misplaced — much like the protein-timing myth in what to eat after training, the day's total matters more than the minute the dose lands.

How to take it

This is the part people overcomplicate. There are two valid approaches, and they arrive at exactly the same place — a fully saturated muscle — at different speeds.

1. Load, then maintain: 20 g per day (split into four 5 g doses) for 5–7 days, then 3–5 g per day thereafter. Saturates muscle in under a week.
2. Just maintain: 3–5 g per day from the start. Saturates muscle in about three to four weeks. Same endpoint, gentler on the stomach, one fewer thing to think about.

Loading is useful if you want the effect quickly — before a season starts, say. For everyone else, the daily 3–5 g approach is simpler and just as effective in the long run. Take it whenever you will remember to take it consistently; daily timing is what matters, not whether it lands before or after a workout. (Our piece on pre-workout nutrition makes the same point: creatine works on saturation, not on the clock.)

Monohydrate versus everything else

Monohydrate is the form used in almost every study, it is the cheapest, and nothing has beaten it. Hydrochloride, buffered ('Kre-Alkalyn'), ethyl ester, liquid, and the rest are sold on claims of better absorption or less bloating, but when they are tested head-to-head they match monohydrate at best and underperform it at worst — at several times the price. Look for a product carrying the Creapure label or a third-party purity certification and ignore the marketing adjectives.

The myths, briefly

• 'It's just water weight.' The first 1–2 kg is water — held inside the muscle cell, not under the skin. That intracellular water is part of how it works, and lean mass gains beyond it accrue from the extra training it enables.
• 'It wrecks your kidneys.' In people with healthy kidneys, long-term studies up to five years show no harm. Creatine does raise serum creatinine, a breakdown product — which can make a routine kidney blood test look abnormal without anything actually being wrong. Tell your doctor you supplement.
• 'It causes hair loss.' This traces to a single 2009 study that found a rise in DHT and never measured hair at all. It has not been replicated, and no trial has shown creatine causing hair loss.
• 'You have to cycle off it.' You do not. There is no evidence the body downregulates its own production to a problematic degree, and no benefit to periodic breaks.
• 'It causes bloating and cramps.' Large doses taken all at once can upset the stomach; splitting the dose or skipping the loading phase resolves it. The cramping claim has not held up in trials — if anything creatine is associated with fewer cramps.

Responders and non-responders

Not everyone responds equally. The size of the effect depends largely on how depleted your muscle stores were to begin with: the emptier the tank, the more dramatic the top-up. This is why vegetarians and vegans, who start with little dietary creatine, tend to see the biggest improvements, and why some habitual heavy-meat-eaters notice comparatively little — they were already most of the way to saturated. An estimated 20–30% of people are 'low responders' whose stores were already high. If you are one of them, creatine is simply doing less work because your diet was already doing it.

Beyond the gym

The brain also uses phosphocreatine, and a growing body of research is looking at creatine outside of muscle. The most promising signals are in older adults — where creatine paired with resistance training improves lean mass and strength and may help blunt age-related muscle loss — and in cognition under stress, where supplementation appears to help most when the brain is taxed by sleep deprivation or when baseline stores are low, as in vegetarians. The effect in well-rested, well-fed people is far less clear, the doses that may matter for the brain look higher than the 3–5 g used for muscle, and the long-term picture is still being filled in. It is a reasonable thing to watch; it is not yet a settled reason to take it.

Who should be cautious

For healthy adults, creatine has one of the cleanest safety records of any supplement on the market. The exceptions are straightforward: anyone with existing kidney disease should not start it without a clinician's input, because the kidneys handle its excretion; and there is not enough data to make confident recommendations in pregnancy. For everyone else, the honest summary is unusually boring for a supplement — it works, it is cheap, and it is safe.