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.
Steroid-induced osteoporosis (SIOP) is osteoporosis arising due to use of glucocorticoids (steroid hormones) - analogous to Cushing's syndrome and involving mainly the axial skeleton. The synthetic glucocorticoid prescription drug prednisone is a main candidate after prolonged intake. Bisphosphonates are beneficial in reducing the risk of vertebral fractures.  Some professional guidelines recommend prophylactic calcium and vitamin D supplementation in patients who take the equivalent of more than 30 mg hydrocortisone ( mg of prednisolone), especially when this is in excess of three months.   The use of thiazide diuretics, and gonadal hormone replacement has also been recommended, with the use of calcitonin, bisphosphonates, sodium fluoride or anabolic steroids also suggested in refractory cases.  Alternate day use may not prevent this complication. 
Glucocorticoid therapy is associated with an appreciable risk of bone loss, which is most pronounced in the first few months of use. In addition, glucocorticoids increase fracture risk, and fractures occur at higher bone mineral density (BMD) values than occur in postmenopausal osteoporosis. The increased risk of fracture has been reported with doses of prednisone or its equivalent as low as to mg daily [ 1 ]. Thus, glucocorticoid-induced bone loss should be treated aggressively, particularly in those already at high risk for fracture (older age, prior fragility fracture). In other individuals, clinical risk factor and bone density assessment may help guide therapy. The prevention and treatment of glucocorticoid-induced bone loss will be reviewed here. The clinical features are reviewed separately. (See "Clinical features and evaluation of glucocorticoid-induced osteoporosis" .)