Abstract 06: Body Mass Index Growth Trajectories During Childhood and Adult Obesity Risk

Abstract

Background: Obesity measures track from childhood to adulthood. However, information is limited regarding the relationship between body mass index (BMI) growth trajectories during childhood and adult obesity risk. We hypothesize that BMI growth rates at different childhood age windows have influences on adult obesity, independent of absolute BMI values. Methods: The longitudinal study cohort consisted of 2,732 adults (1,772 whites and 960 blacks; 1,226 males) who had BMI measured at least 4 times from childhood (4-19 years) to adulthood (20-51 years). A random-effects mixed model was used to construct growth curves of BMI from childhood to adulthood in race-sex groups. Model-estimated linear growth rates (kg/m 2 /year) in BMI at different childhood ages, calculated by using the first derivatives of the growth curves, were linked to adult obesity (BMI>=30) in multivariable regression models, adjusted for adult age, race, sex, adult smoking and alcohol drinking, and childhood BMI levels. Results: BMI from childhood to adulthood fit cubic growth curves; linear and nonlinear curve parameters differed significantly between race-sex groups. BMI levels showed race and sex differences from age 15 years onwards. Obese adults had significantly higher BMI levels than non-obese adults from childhood to adulthood. Differences in linear and nonlinear slope parameters of BMI between obese and non-obese groups were all significant (p<0.001). The association patterns of childhood BMI growth trajectories with adult obesity were similar in all race-sex groups. In the total sample, the association between childhood BMI growth rate and adult obesity was peaked at age 17 (odds ratio=5.7 and 95% confidence interval=4.7-6.8) as shown in the figure. Conclusions: These observations indicate that adult obesity originates in early life with different longitudinal BMI trajectory profiles. Puberty is a crucial period for the development of obesity in later life, which has implications for obesity prevention beginning in childhood.