We think of Osteoporosis as something that only affects people over 50, but the truth is, we build most of our bone density in our teens! Many kids are not getting enough calcium and exercise, which means they don’t build as much bone density as they need in life. The average girl grows the fastest in height between the ages of 11 and 12 years, and stops growing between the ages of 14 and 15 years. About 95% of a young woman's peak bone mass is present by age 20, and some ov