Psychological and physical health of mostly heterosexuals: a systematic review.

We reviewed whether mostly heterosexuals, a sexual orientation group characterized by a small amount of same-sex sexuality, differ from heterosexuals and bisexuals on a variety of mental and physical health outcomes (e.g., internalizing problems, body dissatisfaction and disordered eating, obesity, sexual/reproductive health, physical health), health risk behaviors (e.g., substance use, sexual risk taking), and risk and protective factors (e.g., victimization, stressful/risky environment, socioeconomic status, personal and social relationships, gender nonconformity). A narrative and quantitative literature review was conducted of 60 papers covering 22 samples from five Western countries. Individual, mean, and median effect sizes (Cohen ds) were calculated whenever possible. Mostly heterosexuals reported higher levels of risk in most reviewed outcomes compared to heterosexuals (unweighted mean effect sizes ranged from 0.20 to 0.50) but typically somewhat lower than bisexuals (unweighted mean effect sizes ranged from -0.10 to -0.30). Various risk factors frequently reduced, but rarely eliminated, health disparities between mostly heterosexuals and heterosexuals. Findings are discussed through the lens of three potential explanations of elevated health risks among nonheterosexuals: minority stress, nonheterosexual lifestyles, and common causes. Because data on many outcomes were scarce or missing, particularly for men and in comparison with bisexuals, further research is needed.