Association between obesity and femoral neck strength according to age, sex, and fat distribution
CONTEXT Bone loss is considered to begin with menopause in women and later in life in men; however, several recent studies have reported that bone loss began in young adults. There are still discordant results concerning age-related changes in bone mineral density (BMD), especially in nonvertebral bone. OBJECTIVE The objective of the study was to investigate the age-related changes in BMD in Korean youth. DESIGN AND SETTING This was a population-based, cross-sectional study from the Fourth Korea National Health and Nutrition Examination Surveys. PARTICIPANTS A total 10,575 Korean (4,731 males and 5,844 females) aged 10-80 yr were included. MAIN OUTCOME MEASURES BMD at the spine and hip was measured using dual X-ray absorptiometry. RESULTS Age-related bone loss at the femoral neck in males occurred continuously with temporary acceleration phase after achieving peak bone mass (PBM). In contrast, age-related bone loss at total hip in both sexes and femoral neck in females showed three obvious phases: acceleration, consolidation, and then the second acceleration phase after reaching PBM. Interestingly, this pattern of bone loss was more significant in the total hip and thus showed the acceleration phase until the late 20s and the consolidation phase until the late 40s. Early accelerated loss of BMD was not observed at the lumbar spine in each sex. Although body mass index and body fat percentage were more related with BMD than other clinical parameters, they could not explain the early accelerated loss of BMD at the femur. CONCLUSIONS There was an accelerated bone loss at the femur in both sexes during early adulthood and more than 60% of the bone loss before age 50 yr occurred during this period.