Risk Factors for the Onset of Eating Disorders in Adolescent Girls: Results of the McKnight Longitudinal Risk Factor Study

OBJECTIVE: This study examined the importance of potential risk factors for eating disorder onset in a large multiethnic sample followed for up to 3 years, with assessment instruments validated for the target population and a structured clinical interview used to make diagnoses. METHOD: Participants were 1,103 girls initially assessed in grades 6–9 in school districts in Arizona and California. Each year, students completed the McKnight Risk Factor Survey, had body height and weight measured, and underwent a structured clinical interview. The McKnight Risk Factor Survey, a self-report instrument developed for this age group, includes questions related to risk factors for eating disorders. RESULTS: During follow-up, 32 girls (2.9%) developed a partial- or full-syndrome eating disorder. At the Arizona site, there was a significant interaction between Hispanics and higher scores on a factor measuring thin body preoccupation and social pressure in predicting onset of eating disorders. An increase in negative life events also predicted onset of eating disorders in this sample. At the California site, only thin body preoccupation and social pressure predicted onset of eating disorders. A four-item screen derived from thin body preoccupation and social pressure had a sensitivity of 0.72, a specificity of 0.80, and an efficiency of 0.79. CONCLUSIONS: Thin body preoccupation and social pressure are important risk factors for the development of eating disorders in adolescents. Some Hispanic groups are at risk of developing eating disorders. Efforts to reduce peer, cultural, and other sources of thin body preoccupation may be necessary to prevent eating disorders.