Creatine Benefits: They Screened 250 Supplements. Two Survived.

In 2003 two researchers did something the supplement industry has never quite recovered from. They took every dietary supplement claimed to build muscle, set a minimum standard of evidence, and counted how many cleared it.

They examined 250 supplements. Only six had more than two studies that met the entry criteria — three weeks minimum, resistance training at least twice a week. [1]

Of those six, two produced a significant effect.

Creatine was one of them. Twenty-odd years and several meta-analyses later, it still is.

How much muscle, actually

The most recent and most carefully run analysis pooled twelve trials in adults under fifty, with the protocol registered in advance so the authors could not go fishing after the fact. [2]

Against resistance training alone, adding creatine produced 1.14 kg — about 2.5 lb — of extra lean body mass (95% confidence interval 0.69 to 1.59 kg). Body fat mass fell by 0.73 kg, roughly 1.6 lb, and body fat percentage by 0.88 points. [2]

The authors put it in practical terms: about 7 grams a day, or 0.3 grams per kilogram of bodyweight, “is likely to increase LBM by 1 kg and reduce fat mass by 0.7 kg more than RT alone.” [2]

Two and a half pounds is not a transformation. It is also two and a half pounds you would not otherwise have, from a compound that costs pennies a day and has been studied for thirty years. Almost nothing else in the supplement aisle can make that claim — which is rather the point of the table above.

The finding that runs against the marketing

Creatine is sold to young men. It appears to work better in people considerably older.

A meta-analysis of 22 trials covering 721 participants with a mean age between 57 and 70, training two to three days a week for anything from seven weeks to a year, found creatine added 1.37 kg of lean tissue — about 3 lb (95% CI 0.97 to 1.76, p < 0.00001). [3]

Strength improved too: standardised effect sizes of 0.35 for chest press and 0.24 for leg press.

Compare that with the 1.14 kg in the under-fifties. The older group got more, not less. Which makes sense if you think about what creatine does — it tops up a fuel reserve inside muscle, and people who have lost muscle with age have more room to top up.

What it actually does, in one paragraph

Your muscles hold a small store of phosphocreatine, which regenerates ATP — the molecule that powers a contraction — during very short, very hard efforts. That store runs out in seconds, which is why the eighth rep is harder than the second.

Supplementing raises the size of that store. The International Society of Sports Nutrition’s position stand puts it plainly: creatine “increases intramuscular creatine concentrations which may help explain the observed improvements in high intensity exercise performance leading to greater training adaptations.” [5]

Note the causal chain, because it matters. Creatine does not build muscle directly. It lets you do slightly more work, and the extra work builds the muscle. That is why every study on this page pairs it with resistance training — on its own it is a full fuel tank in a parked car.

Where the effect is biggest, and where it is smallest

The largest early meta-analysis pooled 100 randomised, placebo-controlled studies and broke the results down by the kind of exercise. [4]

Effect sizes — a standard scale where 0.2 counts as small, 0.5 moderate and 0.8 large — came out at 0.42 for upper-body exercise, 0.21 for lower body, and 0.13 for whole-body work. Laboratory tasks like isometric or isokinetic testing showed larger effects (0.25) than field tasks like running or swimming (0.14). [4]

Two honest observations follow. Creatine helps most with short, hard, repeated efforts — which is what a set of bench press is, and is not what a five-kilometre run is. And every one of those numbers is small on the conventional scale.

That is worth sitting with, because it is why we rate creatine Established rather than remarkable. Established means the evidence is consistent and the direction is not in doubt. It does not mean the effect is large.

A caveat on that table, because a date matters

Look back at the 2003 comparison and you will see protein listed as having no significant effect on lean mass or strength. [1]

That was 2003. Protein’s evidence base has moved a very long way since, and it would be dishonest to leave a twenty-two-year-old null standing as a current verdict. We flag it here rather than quietly cropping the row, because cropping inconvenient rows is what this site exists to catch.

What the 2003 result does tell you is how thin the evidence for everything else was, even then. Chromium, DHEA and androstenedione were all being sold hard at the time. None of them cleared the bar.

About “before and after”

This is one of the most searched questions about creatine, so here is the honest version.

Some of what you see in the first fortnight is water, drawn into the muscle cell along with the creatine. That is real — it genuinely makes muscles look fuller — and it is not the same thing as muscle tissue. Over weeks and months, the lean mass numbers above are what accumulates on top of it. We covered the weight question in its own verdict.

Two and a half pounds of lean mass over a training block does not photograph dramatically. Anyone showing you a picture that does is showing you training, lighting, and time — with creatine somewhere in the mix.

The verdict

Creatine builds muscle and strength. That is Established — replicated across independent meta-analyses in young adults and older adults, in a hundred randomised placebo-controlled studies, with a known dose, a known mechanism, and a direction nobody contests.

Expect roughly 2.5 lb of extra lean mass in adults under fifty, and around 3 lb in older adults, on top of what the training itself delivers. It works best for short, hard, repeated efforts. It does nothing without the training.

The reason it stands out is not that the effect is big. It is that in a field where 250 candidate supplements were screened and only two cleared a modest evidence bar, this one keeps clearing it — and it is one of very few things in this whole corpus that the supplement aisle sells and the evidence actually supports.

The rest of what you probably want to know is already covered: how much to take, whether it is safe, the weight gain, and the hair loss question.

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