He came up with it after years of studying steroid users in Boston-area gyms and comparing them not just to non-steroid users in the same gyms, but also to bodybuilders from different eras. For a 1995 study, Pope and his coauthors estimated the FFMIs of Mr. America winners from 1939 to 1959, before steroids were readily available. The group includes future B-movie star Steve Reeves, whose physique was so iconic that he was name-checked in The Rocky Horror Picture Show . The average FFMI was . (One of the highest was George Eiferman, Mr. America 1948, with a FFMI. His upper body was later the model for George of the Jungle, a 1960s cartoon character.) Even today, with all we’ve learned about training and nutrition, an FFMI in the mid 20s is still considered the ceiling for natural bodybuilders. Anything above 26 or 27 is suspect.