Consistent with previous observations that female African American adolescents tend to gain BMD earlier during adolescence and continue to gain bone later in adolescence than Caucasian adolescents [8,31,32], the current study noted that the African American participants had higher mean BMD levels at baseline than Caucasian participants, despite similar mean chronological and gynecologic ages. On average, the African American subgroup lost less BMD at the TH over the course of the study. Higher mean BMD and BMI in the African American participants may have influenced the rate and extent of BMD change, along with a lower proportion of participants who smoked cigarettes, which is generally associated with lower BMD