How, When, and for Whom Does Daily Weight Bias Internalization Undermine Body Image Satisfaction? A Daily Diary Study...

Although body image satisfaction is increasingly recognized as a dynamic experience that fluctuates across daily contexts, little is known about how weight bias internalization shapes these fluctuations or the cognitive mechanisms and contextual factors involved. The present study examined whether perceived weight mediates the association between weight bias internalization and body image satisfaction, whether exercise duration moderates this association, and whether these effects differ by gender. Daily diary data were collected over 10 consecutive days from 305 Chinese adolescents (M_age = 12.59 years, SD = 0.63 years; 49.2% girls). Multilevel analyses revealed that, at both within- and between-person levels, higher weight bias internalization was associated with lower body image satisfaction. Perceived weight significantly mediated the association between weight bias internalization and body image satisfaction at both levels. Additionally, exploratory analyses using dynamic structural equation modeling further indicated that perceived weight mediated the relationship between weight bias internalization and body image satisfaction at the between-person level, but not at the within-person level. Furthermore, exercise duration moderated the association between perceived weight and body image satisfaction among female adolescents but not among male adolescents. Specifically, the negative association between perceived weight and body image satisfaction was stronger on days when girls engaged in more exercise than usual and among girls with higher average exercise duration. In addition, exercise duration moderated the indirect association between weight bias internalization and body image satisfaction through perceived weight at both within- and between-person levels among girls. These findings highlight the dynamic cognitive processes linking weight bias internalization to body image satisfaction, and the importance of considering gender and daily exercise context in understanding adolescents' body image experiences.