Body Composition Development of Adolescent White Females

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Abstract
Objective To obtain simultaneous and longitudinal measures of height, weight, total body bone mineral content, total body bone mineral density, percentage of body fat, lean body mass, and body mass index in healthy white females between the ages of 11 and 18 years. Design A longitudinal, observational study. Setting University medical center in a small city. Study Participants At initiation in 1990, 112 premenarchal, healthy girls were enrolled. Results presented in this report are based on measurements made on the 82 participants who remained in the study in 1996 and for whom we had comprehensive measurements. Interventions None. Main Outcome Measures Dual-energy x-ray absorptiometry was used to obtain measurements of total body bone mineral content, total 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 thereafter. Results The mean age for peak velocity and peak accumulation for each measurement was as follows: height, 11½ and 17½ years, respectively; weight, 11½ and 17½ years; body mass index, 11½ and 17½ years; percentage of body fat, 11½ and 13½ years; lean body mass, 12 and 17½ years; total body bone mineral content, 13½ and 17½ years; and total body bone mineral density, 13½ and 17½ years. Conclusions Among a healthy population of white females, the age of peak velocities for height, weight, body fat, and lean body mass occur at 11½ to 12 years. Thus, peak soft-tissue velocities precede hard-tissue velocities by about 2 years, with peak accumulation of all tissue components being reached, on average, by age 17½ years.