Working with six waves of data from a prospective cohort, we examined temporal patterns in weight status as they differentially affected sexual orientation subgroups throughout adolescence. Among females, we observed fairly consistently elevated BMI in sexual orientation minority groups relative to heterosexual peers. In contrast, among males we documented a sexual-orientation-by-age interaction not seen in females in our analyses, and this pattern was most pronounced in gay males. Specifically, in males we observed evidence of steeper increases in BMI with age from early to late adolescence in heterosexuals relative to sexual orientation minorities. We also observed a significant gender-by-sexual orientation interaction in attained weight status by ages 21-23 years. The prevalence of overweight in young adulthood was much higher in lesbians (39%) and heterosexual males (42%) than seen in heterosexual females (26%) and gay males (26%).
Studies with adult women have consistently found lesbian and bisexual women to have BMIs higher than those of heterosexual women.(3
) Our research indicates that this disparity among women begins by adolescence. In addition, our study identified adolescent girls who describe themselves as “mostly heterosexual” as a group at elevated risk for overweight. Little attention has been given to understanding weight status among “mostly heterosexuals,” who are the largest sexual orientation minority subgroup (12.0% of females by age 22 years in our cohort compared to 4.3% who are bisexual or lesbian at those ages).
Our finding of higher BMI in heterosexual adolescent males relative to sexual orientation minority males by late adolescence is consistent with two studies in adult men.(6
) In contrast, our findings differ from one study conducted with a school-based sample of adolescents that did not find sexual orientation to be associated with BMI;(8
) however, data from this Minnesota school-based study were collected more than 20 years ago, so discrepancies with our findings may be due to changes in temporal trends in childhood overweight or other factors.
In interpreting our finding of a steeper increase in BMI from ages 12-14 to 21-23 years in heterosexual compared to sexual minority males, it is important to note that heterosexual males in our cohort reported the lowest mean BMI and lowest prevalence of overweight of the four sexual orientation subgroups at ages 12-14 years and gay males report the highest. This difference at the youngest ages may be in part due to transient subgroup differences in maturation(20
) in which boys who are aware of same-sex sexual feelings at ages 12-14 years and describe themselves as gay, bisexual, or “mostly heterosexual” at these ages may be further along in pubertal development than same-age peers who describe themselves as heterosexual. At subsequent ages, the heterosexual males as a group in our cohort make steeper gains in weight than the sexual minority subgroups during the years of pubertal development, perhaps a sort of maturational catch-up. Maturational catch-up, however, could not explain patterns observed by ages 21-23 years in attained BMI and weight status, a period in which gay males have been surpassed by the other subgroups and report the lowest attained BMI and lowest prevalence of overweight.
The multiple factors that are likely to underlie sexual orientation-related weight status disparities are not understood, but attention to recent research on stress and its relationship to weight-related behaviors and obesity may illuminate plausible pathways, particularly to explain disparities observed in females. Common manifestations of the stress response, both behavioral and physiological, have been linked to weight status. Stress-related coping behaviors, including unhealthful dietary and physical activity patterns, television viewing, and disrupted sleep patterns, have been identified as risk factors for weight gain and obesity.(21
) A study of college-age women found that higher stress was connected with binge eating.(23
) Emotional vulnerability and difficulty regulating negative moods has also been positively associated with binge eating(24
) and eating in the absence of hunger.(25
) In children and preteens, television viewing is a common coping strategy in response to stress.(26
) Stress-related physiological perturbations, such as dysregulation of diurnal cortisol, have also been linked with obesity.(28
Sexual minority adolescents experience unique stressors in environments that stigmatize minority sexual orientations.(33
) For instance, lesbian, gay, and bisexual youth experience higher rates of bullying and violence victimization than do heterosexual youth.(34
) Concealing one's sexual orientation can be a stressor(33
), but also disclosure that results in conflict with and rejection by parents can contribute to stress on sexual minority youth.(37
) Youth whose parents are aware of their minority sexual orientation report significantly higher rates of verbal victimization related to sexual orientation than those whose parents are not aware.(39
) Futhermore, at-school victimization(40
) and family rejection(37
) have been linked with elevated rates of substance use, suicidality, and sexual risk behaviors in sexual minority youth. Building on this evidence, it is plausible that sexual minority youth may also experience behavioral and physiological stress responses that have been linked with weight-related behaviors and weight status.
The observed sexual-orientation-related disparities in weight status suggest important differences in weight-related behaviors. A small number of studies have begun to examine weight-related behaviors of sexual orientation minority populations, but findings are sparse and contradictory. Most of these studies have been focused on adult women rather than youth or males. The Women's Health Initiative found that lesbians consumed fewer servings of fruits and vegetables per day than did heterosexual women.(41
) Aaron and colleagues, in a study comparing a sample of 1,017 lesbians to the general population of women participating in the CDC's Behavioral Risk Factor Surveillance System Survey, found no orientation group difference in the samples in sedentary behavior (approximately one third of each group reported no physical activity)(42
), and another study comparing heterosexual, bisexual, and gay men and women found no differences across sexual orientation groups in sports participation.(43
) Yet, three studies with adult women have found lesbians to be more physically active than heterosexual women.(5
) Higher rates of binge eating have been found in sexual orientation minorities, both female and male, compared to heterosexuals, including in the GUTS cohort.(8
Importantly, in our study, when examining risk of overweight by young adulthood, we observed that gender significantly modified the relationship between sexual orientation and risk of overweight. Specifically, at ages 21-23 years, lesbian and “mostly heterosexual” females were at higher risk of overweight than heterosexual females; whereas, gay and “mostly heterosexual” males were at lower risk of overweight than were heterosexual males. This finding suggests that a hypothesized pathway as laid out above, from sexual-minority-related stress to behavioral and physiological stress responses to excess weight gain may apply to female more so than to male sexual minorities. It is possible that in response to sexual-minority-related stress, females are more likely than males to adopt specific coping behaviors linked with weight gain. Interestingly, an experimental study by Rutters et al. provides some support for gender differences in the effect of stress on excess caloric intake.(25
) In a study of eating in the absence of hunger with adult women and men, Rutters and colleagues found not only that study participants exposed to stress consumed more kilocalories compared to those in the control condition but that the subset of participants who had scored high on a measure of disinhibited eating (defined as a loss of control over eating when palatable food is available or when emotionally upset(47
)) were the most vulnerable to increased caloric intake in response to the stress condition. Women in the study had significantly higher disinhibited eating scores than did men.(25
) Further research will be essential to examine the many questions that remain as to whether and how gender differences in weight-related aspects of stress responses and specifically disinhibited eating may contribute to the distinct gender-by-sexual-orientation patterns observed in weight status in adolescence and young adulthood.
Our study has several limitations. The GUTS cohort is not a representative sample, and participants, most of whom are of white race/ethnicity, are children of registered nurses and therefore are likely to encompass a more narrow range of the socioeconomic spectrum than exists in the U.S. as a whole. As a result, generalizability may be limited. It is worth noting, though, that our study is not affected by sexual orientation-related enrollment bias, as our sample was not recruited on the basis of sexual orientation. While the GUTS cohort is relatively large and our analyses included a total of 56,990 observations drawn from multiple assessments, small sample sizes particularly affected stability of estimates for lesbians and bisexual males, the two smallest subgroups. For instance, though data presented in the Figure would suggest that lesbians have relatively low BMI in the youngest age group and bisexual males to have relatively high BMI at the oldest age group, these are periods when their numbers are most sparse (see ); therefore, patterns should be interpreted with caution. Alternately, there may be some meaningful group differences that were not found to be statistically significant due to small sample sizes (type II error). A strength of the sexual orientation item used on the GUTS questionnaires is that it is constructed as a scale and allows variability at the heterosexual end of the range, enabling us to identify the large subset youth who experience both-sex attractions and describe their feelings as “mostly heterosexual.” This group would have been overlooked had the survey included a conventional measure of sexual orientation identity, which typically uses the more condensed response options heterosexual, bisexual, and lesbian/gay.
On GUTS questionnaires, height and weight are self-reported, which is less accurate than measured values, though adolescents have been found to be able to provide valid reports of height and weight.(48
) It is unknown whether there may be sexual-orientation-related bias in self-reported height and weight. For instance, it is plausible that gay males may underreport their weight more so than heterosexual males, due to greater weight concerns among gay males.(49
) Methodological studies will be needed to investigate this potential source of bias in research on weight status.
Our study demonstrates that sexual orientation group disparities in BMI are evident early in adolescence. We found a fairly consistent relationship between minority sexual orientation and elevated BMI in females, particularly at the older ages in the observed period. In contrast, in males we identified a significant age-by-sexual-orientation interaction. Gains in BMI from early through late adolescence in heterosexual males was notably higher than that in sexual orientation minority males. We also found a significant gender-by-sexual-orientation interaction in attained weight status by young adulthood in which sexual minority females but not sexual minority males were at elevated risk of overweight. The long-term health consequences of excess weight are well-documented(2
) and over time are likely to exact a high toll on communities with elevated rates. Sexual orientation group disparities found among females in the GUTS cohort are as large as those observed in other national studies comparing BMI across racial/ethnic and socioeconomic groups.(51
) Additional prospective research among both genders is needed to understand the determinants of these differences. Mechanisms driving orientation group patterns in weight status are likely to be multifaceted and need to be identified to inform effective preventive and treatment intervention strategies for all youth.