The purpose of this study is to determine whether administration of an investigational medication called leptin (r-metHuLeptin) in replacement doses can improve bone health, reproductive function, hormone levels, immune function, and overall sense of well-being in women with hypothalamic (exercise-induced) amenorrhea (HA) who are being treated with oral contraceptive pills (OCPs), compared to placebo. Women with hypothalamic amenorrhea have low leptin levels. This study is based on the hypothesis that the relative leptin deficiency in women with hypothalamic (exercise-induced) amenorrhea may be the reason for the lack of menstrual cycles, hormone abnormalities, and bone loss associated with this condition.