Objective: To explore the experiences of obesity among junior high school students, and reveal its core themes and essential features, so as to provide evidence for health promotion. Methods: From March to August 2025, semi structured in depth interviews were conducted with 22 obese junior high school students (15 boys,7 girls) aged 13-16 years from two junior high schools in Beijing and one junior high school in Shenyang.Each interview lasted about 40 minutes, and the outline of the interview mainly involved three dimensions: obesity experience, obesity life experience, suggestions and future expectations. Data were analyzed using Moustakas phenomenological method. Results: A total of 4 core themes and 13 sub themes were identified: health experiences (external discipline, health conflicts, perceptual tension), exercise experiences (restricted activity, weight loss expectations, psychological catharsis, physical education test pressure), emotional experiences (appearance anxiety, self soothing, generalized impact), and social experiences (social devaluation, external support, covert suppression). Conclusions Obesity is a complex experience co-constructed by body awareness, physiological indicators, and sociocultural factors. Interventions should enhance students’ body awareness, facilitate a shift from external discipline to internal motivation, and form a collaborative health promotion pathway involving families, schools, and society.