The relationship between premorbid weight status and eating disorder onset in adolescents: a longitudinal study

Objective: Adolescents with higher weight status (HWS; body mass index > 85th percentile adjusted for age and sex) are at greater risk of eating disorders (ED). This study examined factors associated with HWS adolescents' increased risk and how weight status interacts with other risk factors to influence ED onset. Method: Australian adolescents (N = 1333; 51.2% female; 11–19 years) completed questionnaires examining ED symptoms and established and emerging risk factors (sex, age, premorbid weight/shape concerns, psychological distress, dieting, and weight-related bullying) at two timepoints 12 months apart (Waves 1 and 2). Results: Compared to lower weight peers, those with HWS had greater odds of ED onset when adjusting for sociodemographic variables (OR = 2.96, 95% CI [1.84, 3.93]), other ED predictors (OR = 2.18, 95% CI [1.46, 3.25]), and experiences of weight-related bullying (OR = 2.20, 95% CI [1.47, 3.28]). The effect of weight status was less pronounced once premorbid dieting, weight/shape concerns, and psychological distress were accounted for, with evidence that weight/shape concerns (OR = 1.17, 95% CI [1.05, 1.30]) and psychological distress (OR = 1.33, 95% CI [1.17, 1.51]) were independently associated with ED onset. No moderation effects were observed. Discussion: Higher levels of premorbid weight/shape concerns and psychological distress for those with HWS appear to contribute to greater ED risk and should be considered for screening and targeted in prevention.