"Use FFMI to reality-check your natural physique goals A landmark 1995 study by Corey and colleagues tested 74 natural lifters and 83 steroid users, measuring each person's fat-free mass index (FFMI) — lean mass divided by height squared — using gold-standard hydrostatic weighing. The researchers found that "not a single" natural lifter exceeded an FFMI of 25, while 100% of lifters above that threshold were on steroids, leading the authors to state that "only rare individuals, perhaps with some genetic or congenital anomalies, may attain an FFMI in excess of 25 without steroids." Knowing your own FFMI lets you set realistic targets: for most men training hard and eating right, a realistic ceiling is FFMI 22–24, translating to roughly 165 lbs at 5'6" or 200 lbs at 6'0" at about 12% body fat. Source: Jeff Nippard, YouTube, How Big Can You Get Naturally? (Science-Based)"