Changes in Body Composition Influence Change in CVD Risk of Diverse Young Women: Tiger Study

Abstract

Body composition differences among white (W), Hispanic (H) and African-American (AA) women are well documented, and cardiovascular disease (CVD) risk factors have been shown to be related to body composition. The effect of change in body composition on CVD risk is less understood. PURPOSE: We tested the hypothesis that changes in body composition influence the change in CVD risk of young women. METHODS: The sample included 452 women who ranged in age from 17 to 34 y. All were college students and participants in a 3-day per week aerobic exercise program over a 9-month period. Each completed 2 or 3 physical exams with a total of 1,026 observations. The race/ethnic composition of the sample was: W, 32%; H, 29%; and AA, 40%. CVD risk was based on total cholesterol (C), glucose (G), and blood pressure (SBP, DBP). The body composition variables used were: percent fat (%fat) estimated from skinfolds; and the ratio of waist and hip circumference (WHR). Linear mixed models (LMM) was used to test the hypothesis while controlling for race/ethnic group and test exam. Separate models were used for each CVD risk variable. RESULTS: The LMM results showed that, with race/ethnic group and exam, statistically controlled, changes in body composition were related to changes in CVD risk. These results showed that changes in %fat and WHR independently influenced changes in CVD risk. The probabilities of the %fat LMM regression coefficients being statistically significant were: C (p=0.010); G (p=0.020); SBP (p=0.001); and DBP (p=0.001). WHR significantly influenced change in G (p=0.001), SBP (p=0.001), and DBP (p=0.001). The probability of the WHR effect on the change in C was p=0.068. CONCLUSIONS: The results of this longitudinal study showed that, with group change between exams and race/ethnic group statistically controlled, individual differences in the change of %fat and WHR were independent sources of change in CVD risk. These results document the need to examine the lipid and metabolic profile of young adults in greater detail. Supported by NIH Grant DK62148.