Creatine: What It Does, How Much to Take, and the Kidney Question
Creatine paired with resistance training adds strength and lean muscle beyond what training builds alone, and the effect is largest in adults in their sixties and seventies, where it helps offset the muscle loss of aging. A newer line of research shows a memory benefit, concentrated in older adults and close to nothing in people who are young and rested.
Creatine is a compound your body makes and stores mostly in muscle, where it holds a fast energy reserve called phosphocreatine. You also get some from red meat and fish. A daily supplement, plain creatine monohydrate, raises muscle creatine when your own production and diet leave it low, and that fuller reserve is what adds to performance.
Strength and lean mass gained alongside training is the best-established finding: pooled across roughly 100 placebo-controlled trials, the added gain over training alone is small in any single study but consistent across the literature, and it shows up most in short, hard efforts and upper-body lifts. Older adults benefit most: across 22 trials in people aged 57 to 70, adding creatine to a supervised resistance program built about 3.1 lb (1.4 kg) more lean mass and more strength than the same training with a placebo, offsetting the muscle a body loses with age. Memory is a newer and less settled line of evidence: pooled across 8 trials, creatine improved memory overall, though the benefit concentrated in adults aged 66 to 76 and was close to absent in people aged 11 to 31. The bone-density evidence stays mixed, and any benefit there likely runs indirectly, through the muscle and strength built around bone; a direct effect on bone itself has not been shown.
Starting is simple: 3 to 5 grams a day of plain creatine monohydrate, taken any time, with or without food. That saturates the muscle store in three to four weeks. A loading week, about 20 grams a day for five to seven days, gets there in about a week instead; it's optional, and the end point is the same. The large single doses used for loading are what cause the stomach upset some people report.
Expect a little weight on the scale in the first few weeks; that's water drawn into the muscle cell, and any strength or size gained after that comes from your training. Creatine's controlled research does not support kidney harm in healthy people, though it raises a lab marker used to estimate kidney function, so tell whoever orders the test that you supplement. With existing kidney disease, dialysis, or pregnancy or breastfeeding, check with a clinician first.