BODY-COMPOSITION DEVELOPMENT OF ADOLESCENT WHITE FEMALES - THE PENN-STATE YOUNG WOMENS HEALTH STUDY

Objective: To obtain simultaneous and longitudinal measures of height, weight, to tal body bone mineral content, total body bone mineral den sity, percentage of body fat, lean body mass, and body mass index in h ealthy white females between the ages of 11 and 18 years. Design: A lo ngitudinal, observational study. Setting: University medical center in a small city. Study Participants: At initiation in 1990, 112 premenar chal, healthy girls were enrolled. Results presented in this report ar e based on measurements made on the 82 participants who remained in th e study in 1996 and for whom we had comprehensive measurements. Interv entions: None. Main Outcome Measures: Dual-energy x-ray absorptiometry was used to obtain measurements of total body bone mineral content, t otal body bone mineral density, percentage of body fat, and lean body mass every 6 months for the first 4 years of the study and yearly ther eafter. Results: The mean age for peak velocity and peak accumulation for each measurement was as follows: height, 111/2 and 171/2 years, re spectively; weight, 111/2 and 171/2 years; body mass index, 111/2 and 171/2 years; percentage of body fat, 111/2 and 131/2 years; lean body mass, 12 and 171/2 years; total body bone mineral content, 131/2 and 1 71/2 years; and total body bone mineral density, 131/2 and 171/2 years . Conclusions: Among a healthy population of white females, the age of peak velocities for height, weight, body fat, and lean body mass occu r at 111/2 to 12 years. Thus, peak soft-tissue velocities precede hard -tissue velocities by about 2 years, with peak accumulation of all tis sue components being reached, on average, by age 171/2 years.