Obesity, perceived weight discrimination, and hair cortisol: a population-based study

Background and purpose: Stigmatization of individuals with obesity is pervasive and may act as a psychological stressor. The present study examined whether perceived weight discrimination mediated the relationship between obesity and cortisol, an objective marker of chronic stress, in a population-based sample. Methods: Data were from the English Longitudinal Study of Ageing (n = 1872). Height and weight were objectively measured in 2008/09. Experiences of weight-related discrimination were reported via questionnaire in 2010/11. Hair cortisol concentrations were determined from the scalp-nearest 2 cm hair segment in 2012/13. Mediation analyses tested the role of perceived weight discrimination in the associations between obesity and BMI and hair cortisol concentration, adjusting for age, sex, ethnicity, socio-economic status, smoking status, depression and hair-related factors. Results: Obesity, BMI and perceived weight discrimination were positively related to hair cortisol (all p < .01). Perceived weight discrimination significantly mediated associations between obesity and hair cortisol (beta = 0.021, SE = 0.007, 95% CI 0.007-0.036) and BMI and hair cortisol (beta = 0.001, SE = 0.0004, 95% CI 0.0004-0.002), accounting for 19% of the total effect of obesity and 23% of the total effect of BMI on hair cortisol. Conclusions: Perceived weight discrimination is an important mediator of the association between obesity and cortisol. Interventions combating weight stigma and discrimination or promoting strategies for coping with stress could help to lessen the psychological and physiological burden of obesity.