Expected changes in clinical measures of adiposity during puberty

Abstract

Background: Clinicians use several measures to estimate adiposity. Body mass index (BMI), although not a measure of adiposity, is commonly used to define weight status. Percent body fat (%BF) measures total body fatness, which is composed of central and peripheral fat, estimated by waist circumference (WC) and skinfold thickness, respectively. Abnormal increases in fat during puberty may reflect an increased risk of developing cardiovascular disease. Therefore, it is important to establish the normal patterns of change in clinically relevant measures of adiposity.

Purpose: To describe the normal patterns of change in clinical measures of adiposity during puberty.

Design/methods: Multilevel modeling and linear regression analyses of 642 children in Project HeartBeat!, aged 8-18 years (non-black and black), who had assessments of BMI, %BF, WC, sums of 2- and 6-skinfolds, and pubertal stage (PS) triennially between 1991 and 1995.

Results: In males, the normal pattern from PS1 to PS5 is for %BF to decrease, skinfold thickness to remain stable, and WC to increase. However, after adjusting for height, WC does not change. In females, %BF remains stable from PS1 to PS5, whereas skinfold thickness increases. As in males waist-height ratio does not change, indicating that central adiposity does not normally increase during puberty. Although BMI increases in both genders and races from PS1 to PS5, mean values at PS5 were well below 25 kg/m(2).

Conclusions: During puberty, increase in %BF is abnormal in females and even more so in males. Likewise, increase in waist-height ratio is also abnormal and may suggest an increased risk for adiposity-associated morbidity.

Figure 1

◆, Non-black males; ■, black males; ▲, non-black females; ●, black females. All datapoints in Figures 1A–F are least squares means ± standard error at each pubertal stage (PS; based on breast/genital development) for 4 race-gender cohorts. Lines connecting datapoints (vertical or horizontal) indicate significant differences between datapoints, p < .0001. Significant differences (p < .0001) between PS1 and PS5 for a race-gender cohort for each measure of adiposity are as follows: (A) Body mass index (BMI): changes between PS1 and PS5 are significant for 4 race-gender cohorts. (B) Percent body fat (%BF): changes between PS1 and PS5 are significant for males. (C) Sum of 2 skinfolds (SF-2): changes between PS1 and PS5 are significant for females. (D) Sum of 6 skinfolds (SF-6): changes between PS1 and PS5 are significant for females. (E) Waist circumference (WC): changes between PS1 and PS5 are significant for 4 race-gender cohorts. (F) Waist circumference/height (WC/Ht): There was no significant change from PS1 to PS5 for any race/gender cohort.