To explore the dynamic association and gender difference among body dissatisfaction, weight bias internalization and eating disorders in junior high school students, so as to provide the reference for the rational implementation of relevant intervention activitites.

From June to December 2023, a cluster sampling method was used to select 698 students from a middle school in Fuzhou for three follow-up surveys for a period of 6 months (T1:June 2023, T2:September 2023, T3:December 2023). The Eating Disorders Inventory-Body Dissatisfaction (EDI-BD), the Chinese Version of the Weight Bias Internalization Scale for Mainland Chinese Children and Adolescents (C-WBIS), and the Chinese Version of the Eating Disorder Examination Questionnaire (C-EDE-QS) were used for investigation. Analysis of variance, t test, Pearson correlation analysis and cross-lagged analysis were used for statistical analysis.

T1 there were statistically significant differences in body dissatisfaction scores among junior high school students of different grades and with or without left-behind experience (t=-3.25, 2.12, P < 0.05). There were statistically significant differences in weight bias internalization (t=-3.03, -2.43, 2.43) and eating disorders (t=-4.64, -2.04, 2.63) among junior high school students of different genders, grades and with or without left-behind experience (P < 0.05). Cross-lagged analysis showed that body dissatisfaction was a predictor of weight bias internalization (β_T1-T2=0.22, β_T2-T3=0.12) and eating disorders (β_T1-T2=0.09, β_T2-T3=0.17, P < 0.01). Eating disorders could predict body dissatisfaction (β_T1-T2=0.15, β_T2-T3=0.13) and weight bias internalization (β_T1-T2=0.14, β_T2-T3=0.23, P < 0.01). The mutual predictive effect of body dissatisfaction, weight bias internalization and eating disorders varied with gender. T2 weight bias internalization in girls had a predictive effect on T3 body dissatisfaction (β=0.11). T1 and T2 eating disorders in girls had a predictive effect on T2 and T3 weight bias internalization (β_T1-T2=0.26, β_T2-T3=0.21) (P < 0.01).

Body dissatisfaction, weight bias internalization, and eating disorders of the junior high school students are interconnected. And there is a certain two-way correlation and gender difference between body dissatisfaction, weight bias internalization and eating disorders in junior high school students.