The weight creatine adds is mostly muscle, not fat

Creatine is one of the most widely used supplements among people who lift, yet questions persist about what it actually changes beyond the number on the bar. Does it only make you stronger, or does it also reshape body composition, and does the extra body weight it brings come from muscle or something less welcome? This analysis set out to answer both questions at once, and to test whether the answer depends on who is taking it: their age, gender and training experience, and how the supplement is dosed and scheduled alongside training.

The researchers systematically searched five major databases from their inception through 21 April 2025, plus backward citation tracking, for trials comparing resistance training with creatine against resistance training alone. Sixty-three studies covering 1489 participants met the criteria. Outcomes included upper- and lower-body strength, lean mass, fat mass, body-fat percentage and total body mass. Effects were pooled using a three-level random-effects model, and possible moderators such as age, gender, training experience, intervention duration, weekly frequency, dosing strategy and daily dose were explored through subgroup analyses and meta-regression.

Adding creatine produced significant gains over training alone in upper-body strength (g = 0.54) and lower-body strength (g = 0.55), along with lean mass (g = 0.30) and a small rise in body mass (g = 0.12). Body-fat percentage fell slightly (g = -0.14), while fat mass itself did not change significantly (g = -0.10). Exploratory analyses suggested younger participants may see larger strength effects, though the age subgroups were unevenly represented and multiple comparisons were run. Notably, no protocol variable, including dosing strategy and daily dose, consistently influenced the outcomes.

This confirms creatine's long-standing reputation as an effective training partner for strength and lean mass, and adds useful nuance: the modest weight gain is attributable to lean tissue, which is why body-fat percentage edged down even though fat mass held steady. The finding that dosing strategy and daily dose did not significantly moderate results complicates the common belief that precise protocols matter greatly. Open questions remain around age, since the exploratory signal favouring younger lifters needs confirmation, and around the incompletely reported diets and training backgrounds across the included trials.

For anyone lifting regularly, this is strong pooled evidence that creatine adds a genuine edge to strength and muscle gain over training alone. It is also a reason not to fear the scale: the weight it adds here was overwhelmingly lean tissue, not fat. The lack of consistent differences between dosing protocols suggests the specific regimen may matter less than simply being consistent, though this analysis was not designed to settle that. Older lifters may see somewhat smaller strength effects, but the evidence on that point is still tentative.