To aid in more targeted eating disorder (ED) prevention efforts, we sought to identify sociodemographic and weight-related risk factors for identified triggers for the onset of anorexia nervosa (AN) in youth. We conducted a retrospective chart review of youth admitted for medical treatment of AN between January 2015 and February 2020. From multidisciplinary admission notes, we extracted patient-reported reasons for diet/exercise changes. We used qualitative thematic analysis to identify ED triggers, then categorized each trigger as binary variables (presence/absence) for logistic regression analysis of risks associated with each trigger. Of 150 patients, mean (SD) age was 14.1(2.3) years. A total of 129 (86%) were female and 120 (80%) were Non-Hispanic White. Triggers included environmental stressors (reported by 30%), external pressures of the thin/fit ideal (29%), internalized thin/fit ideal (29%), weight-related teasing (19%), and receiving health education (14%). Younger age was associated with higher odds of weight-related teasing (p = .04) and health education (p = .03). Males had greater odds of internalized thin/fit ideal than females (p = .04). Those with premorbid body mass indices ≥85th percentile for age and sex had greater odds of reporting positive reinforcement (p = .03) and weight-related teasing (p = .04) than those with weights <85th percentile. We use these findings to detail potential targets for advancing ED prevention efforts.