Disparities in BMI Trajectories from Adolescence to Early Adulthood for Sexual Minority Women


Wood, Sarah M.; Schott, Whitney; Marshal, Michael P.; & Akers, Aletha Y. (2017). Disparities in BMI Trajectories from Adolescence to Early Adulthood for Sexual Minority Women. Society for Adolescent Health and Medicine. New Orleans, LA: Journal of Adolescent Health.


Purpose Sexual minority women (SMW) experience a number of health disparities compared to their heterosexual peers. Cross-sectional studies of body mass index (BMI) have identified increased rates of obesity among SMW. The primary aim of this study was to estimate individual and group-based BMI trajectories and determine the association between sexual identity and BMI from adolescence through young adulthood. Methods We analyzed data from Waves I-IV of the National Longitudinal Study of Adolescent to Adult Health (Add Health) on the 7801 females present in the data at Wave IV. Sexual identity was self-identified at Wave IV and categorized as heterosexual, mostly heterosexual, bisexual, or homosexual (homosexual/mostly homosexual). We conducted group-based trajectory modeling of BMI using the traj command in Stata 13.1 with a censored normal distribution. The best fitting model included three trajectory groups allowing for cubic relationship with time. Multinomial logit regressions predicted the relative risk of BMI trajectory group based on sexual identity, controlling for key background characteristics. Results The mean age of the female sample (n=7801) at Wave I was 16.1 years (y) (SD 1.7). Subjects were 23.1% African-American and 16% Hispanic. The sample was 80.4% heterosexual, 15.4% mostly heterosexual, 2.3% bisexual, and 1.8% homosexual/mostly homosexual. Bisexual adolescents had higher prevalence of parental obesity and sexual abuse before age 15y than heterosexual adolescents; homosexual adolescents had lower prevalence of parental obesity but higher prevalence of sexual abuse before age 15y than heterosexual adolescents. Group-based trajectory modeling identified BMI trajectory groups characterized as: (1) Normal-Stable, with adolescents starting (on average) at Low/Normal (mean BMI<25) and remaining BMI<25 by Wave IV (62.5%), (2) Normal-Obese, starting at Low/Normal BMI but moving to obese (mean BMI>30) by Wave IV (29.1%), and (3) Obese-More Obese, starting obese in adolescence and increasing to morbidly obese (mean BMI>40) by Wave 4 (8.5%). A higher proportion of bisexual women were represented in the Normal-Obese trajectory group (36.6%) than were heterosexual (28.8%) and homosexual women (33.8%). Adjusting for only age, bisexual women had a 62.3% higher risk (RRR 1.62, 95% CI 1.18-2.24, p=0.005) of being in the Normal-Obese BMI trajectory group compared to heterosexual women. Data were only suggestive of elevated risk for the Normal-Obese trajectory group for the mostly heterosexual and homosexual women and Obese-More Obese trajectory groups (p=<0.10). In multinomial logit regressions controlling age, race, parental obesity, family income, rural residence, depression and sexual abuse, the elevated risk of being in the Normal-Obese (RRR 1.51, 95% CI 1.08-2.10, p=0.015) and Obese-More Obese (RRR 1.90, 95% CI: 1.18-3.06, p=0.006) trajectory groups remained significant for bisexual women. Moreover, an elevated risk for mostly heterosexual women emerged (RRR 1.23, 95% CI 1.06-1.41, p=0.005) and homosexuality was only suggestive as a risk factor for the Obese-More Obese trajectory (p=0.07). Conclusions Bisexual women were at increased risk of both developing and worsening obesity compared to heterosexual women. Adjusting for known obesity risk factors had minimal impact on the point estimates for this association. Further research is needed to understand the etiologies for these health disparities in SMW.



Reference Type

Conference proceeding

Book Title

Society for Adolescent Health and Medicine


Wood, Sarah M.
Schott, Whitney
Marshal, Michael P.
Akers, Aletha Y.

Year Published


Volume Number





Journal of Adolescent Health

City of Publication

New Orleans, LA





Reference ID