Evaluating predictors of BMI. Cross-sectional evidence from a Chicago-based cohort

Abstract

Given the prevalence of obesity and overweight, identifying behavioural phenotypes that are associated with weight gain should be given a high priority. In a large and representative sample, we sought to explore the extent to which a range of psychological and demographic variables are associated with body mass index (BMI; in kg/m 2 ). Participants ( N = 283; all females) were recruited from the Chicago area and comprised 118 obese, 69 overweight, and 96 normal-weight individuals. Self-reported eating rate was assessed, together with impulsivity (Barratt Impulsiveness scale version 11 and delay discounting), monetary loss aversion, dietary restraint, and dietary disinhibition. Contrary to previous accounts, our behavioural and self-report measures of impulsivity failed to explain variance in BMI. In this regard, only three variables were significant predictors; dietary disinhibition, highest level of educational qualification, and annual household income. Respectively, these variables accounted for 2%, 1.8%, and 4.3% of the variance in BMI across our sample. Importantly, dietary restraint does not account for relationships between BMI and our demographic variables, suggesting that education and income does not protect against increases in BMI by promoting cognitive restraint. Together, these data indicate that individual personality differences are, in relative terms, poor predictors of BMI and that studies should consider underlying differences that are promoted by socioeconomic status.