The BMDs at L2-4 and FN were significantly associated with body mass index (BMI). After adjustment for age and BMI, multivariate regression analysis indicated that BMDs at L2-4 and FN were associated with current longer exercise duration (L2-4, p = 0.024; FN, p = 0.001), those at L2-4 with milk intake (p = 0.024), and those at FN with consuming breakfast (p = 0.004). Similarly, habits of consuming breakfastand exercising longer (on a weekly basis) during high school were linked with significantly higher L2-4 and FN BMDs. High-impact activities during high school significantly influenced the later BMDs. In conclusion, to maximize peak bone mass, consuming breakfast and completing a longer duration of stronger exercise in the late high school years for at least 10 h per week is recommended.