Creatine monohydrate—one of the most widely studied and popular supplements—has a well-earned reputation for helping increase lean body mass, but some of those gains may come from changes in body water rather than actual muscle growth. A recent study found that creatine monohydrate alone, even without exercise, can boost lean body mass in the short term—especially in women.

Researchers randomly assigned 63 healthy adults to take either 5 grams of creatine monohydrate daily or nothing. After a one-week “wash-in” period with the supplement, everyone began a 12-week resistance training program. The researchers measured lean body mass using a body scan before and after the wash-in and after the training program.

After one week of taking creatine without exercising, those who used the supplement had gained about 0.5 kilograms (roughly 1.1 pounds) more lean body mass than the control group—a difference most apparent in women. Once training began, both groups gained about 2 kilograms (4.4 pounds) of lean body mass over 12 weeks, but creatine users did not gain more than those who did not take it, indicating the supplement gave an early bump in lean body mass but did not enhance long-term gains from resistance training.

These findings suggest that short-term creatine use can raise lean body mass measurements, likely by increasing body water. The investigators posited that higher doses or different timing strategies may be necessary to see continued benefits beyond that initial increase. Learn more about creatine in this episode featuring Dr. Darren Candow.