Longitudinal Associations Between Negative Body Image, Self-Disgust, and Nonsuicidal Self-Injury Among Chinese Adolescents: Disentangling Between- and Within-Person Effects.

Nonsuicidal self-injury (NSSI) and negative body image are both highly prevalent among adolescents, and there are theoretically proposed reciprocal associations between them. However, previous research has not differentiated between stable personal traits and time-varying state levels when examining these associations, and the underlying mechanisms remain unclear. To address these gaps, this study investigated the longitudinal associations between negative body image, self-disgust, and NSSI among Chinese adolescents, disentangling the between- and within-person effects by employing random intercept cross-lagged panel models (RI-CLPMs). A total of 515 Chinese adolescents (50.7% boys; baseline M age  = 12.34 years, SD = 0.47) participated in a four-wave longitudinal study with 6-month intervals. The results indicated that, at the between-person level, higher levels of self-disgust were associated with more NSSI and more concerns about general appearance, facial appearance, shortness, and fatness, but were not associated with concerns about thinness. At the within-person level, general appearance concern and NSSI positively predicted each other over time through self-disgust. Concerns about facial appearance, shortness, and fatness all positively predicted self-disgust, which in turn positively predicted NSSI over time, but not vice versa. These findings highlight the stable and trait-like associations between self-disgust, NSSI, and most negative body image dimensions. Self-disgust is worth considering as a target for intervention, as it plays a mediating role in the long-term associations between negative body image and NSSI.