Stress and weight-related predictors of sexual orientation disparities in BMI trajectories in a longitudinal study of u.s. adolescents and young adults

Obesity is a key public health issue for U.S. adolescents and young adults. Previous research has found sexual minority females to have higher body mass indexes (BMIs) and sexual minority males to have lower BMIs, compared to heterosexuals. This research aimed to explain this health disparity by examining BMI, sexual orientation, severity of child abuse history (indicating exposure to stress), weight-related behaviors, and sociodemographics in 7961 females and 5992 males who participated in the ongoing Growing Up Today Study over nine waves of data collection between 1996 (ages 9-14 years) and 2007 (ages 20-25 years). Using repeated measures of BMI (measured in kg/m-squared units as a continuous outcome) throughout adolescence, latent quadratic growth models adjusted for child abuse severity, weight-related behaviors (e.g., fast food consumption), and sociodemographics (age, race/ethnicity, income). Analyses were stratified by gender and accounted for intracluster correlation due to siblings and repeated measures. Sexual minority females had higher BMIs compared to heterosexual females, with the greatest difference appearing among bisexuals (β=1.42, p<.001), who also displayed greater increases in BMI over time (β=.06, p<.01), compared to heterosexuals. Mostly heterosexual (β=-.05, p<.01) and gay (β=-.22, p<.001) males displayed smaller gains in BMI over time compared to heterosexual males. The differences in BMI and change in BMI were attenuated by as much as 32% after controlling for child abuse severity, weight-related behaviors, and sociodemographics. Sexual orientation differences in BMI were partly explained by child abuse and weight-related behaviors, but more research is needed to explore additional drivers of these disparities.