How do Italian adolescents see themselves? Body weight congruence and its determinants in the 2021/2022 HBSC study

Background Body weight self-perception refers to the level of agreement between an individual’s perceived and actual weight status. Body weight congruence (BWC) indicates the correct perception of one’s body weight compared with its actual value. Understanding the agreement between body mass index (BMI) and weight self perception among adolescents might provide important information regarding health behaviours and psychosocial characteristics in this population. The aim of this study is to investigate the self-perception of body weight among Italian adolescents aged 11, 13, 15, and 17 years, and analyse its congruence with their BMI. Furthermore, it explores the association between BWC and selected socio-demographic and contextual factors. Methods. Data from the Italian Health Behaviour in School-Aged Children (HBSC) survey were used. HBSC is the first Italian population-based survey on adolescent behaviours, representative at national and regional levels and involving students (aged 11, 13, 15 and 17-year-olds have also been included) recruited from school classes throughout all Italian regions. The school class was the primary sampling unit, drawn by a stratified systematic cluster sampling from the list of all public and private schools. Results. In 2022 the Italian HBSC involving 89,321 adolescents. 63.8% of the population correctly perceived their body weight in relation to their BMI category. Overestimation of body weight was more frequent among girls than boys (26.3% vs 9.3%); in contrast, boys were more likely to underestimate their weight (26.0% vs 10.7%). Overestimation climbed from 11 to 17 years, whereas underestimation decreased with age. The risk of weight overestimation and underestimation was associated with adolescents’ health perception; a greater risk was observed among adolescents who considered their health as poor. Conclusions. Overall, our findings corroborate existing literature: body weight misperception decreases with increasing age, girls tend to overestimate their weight, and boys tend to underestimate it. Sex differences represent an important aspect to consider when designing sex-specific interventions in public health.