When ignorance is bliss: weight perception, body mass index and quality of life in adolescents

BACKGROUND/OBJECTIVES: Body weight is negatively associated with adolescent Health-Related Quality of Life (HRQoL). Despite this well-established relationship, some adolescents with obesity do not display the expected HRQoL decreases. This study hypothesised weight perception as a moderator of the association between weight status and adolescent HRQoL. SUBJECTS/METHODS: Subjects were secondary school students from an obesity prevention project in the Barwon South-West region of Victoria, Australia, entitled It's Your Move (N = 3040). Measures included standardised body mass index (BMI-z; World Health Organization growth standards), weight perception and HRQoL, measured by the Paediatric Quality of Life Inventory. Linear regression and average marginal effect analyses were conducted on cross-sectional baseline data to determine the significance of any interaction between weight perception and measured weight status in shaping adolescent HRQoL. RESULTS: The BMI-z/perceived weight status interaction was significantly associated with adolescent HRQoL outcomes. Adolescents with BMI z-scores in the overweight/obesity range who perceived themselves as overweight had lower HRQoL than those who perceived themselves as 'about right.' Conversely, adolescents with BMI scores in the lower end of the normal range or in the thinness range who perceived themselves as underweight had lower HRQoL than those with 'about right' perceptions. CONCLUSIONS: This was the first study to report third-variable impacts of a body-perception variable on the relationship between adolescent weight status and HRQoL. Adolescents' weight perceptions significantly moderated the relationship between overweight/obesity and reduced HRQoL. Adolescents who were outside the normal weight range and misperceived their objectively measured weight status enjoyed a higher HRQoL than adolescents whose weight perception was concordant with their actual weight status. These findings suggest that practitioners may need to exercise caution when educating adolescents about their weight status, as such 'reality checks' may negatively impact on adolescent HRQoL. It is suggested that more research be conducted to examine this potential effect.