Psychosocial Predictors of Body Weight Congruence in Adolescents Aged 15 and 17 Years in Poland: Findings from the Health Behaviour in School-Aged Children (HBSC) Study

Background: Body weight congruence (BWC) has implications for adolescent health. The main goal of this study was to examine the distribution of BWC and its relationship with six psychosocial factors. Methods: A representative sample of N = 3508 adolescents aged 15 and 17 years (52.4% girls) derived from the Health Behaviour in School-aged Children study, conducted in 2017/2018 in Poland, was used. BWC groups were defined based on self-reported BMI and subjective assessment of weight: (1) correct perception; (2) overestimation, and (3). underestimation. Principal component analysis (PCA) extracted the following two factors: a socio-relational factor (SR) related to perceived social support and social self-efficacy, and a body attitudes and social media exposure factor (BAME). Using the total sample, multinomial logistic regression was applied to estimate their impact on the BWC, and gender-specific models were compared. Results: Half (48.6%) of the adolescents correctly estimated their body weight, 31.0% overestimated it (girls 43.9%, boys 17.1%), and 20.0% underestimated it (boys 37.2%, girls 9.0%). Overestimation of body weight concerns 48.0% of normal weight girls, 50.0% of underweight girls, and 21.3% and 32.1% of normal weight and underweight boys, respectively. The percentage of normal weight (34.4%), and overweight and obese (30.8%) boys who underestimated their body weight was three times higher than the respective percentages of girls that underestimated their weight (9.0% and 11.9%). The SR factor protected adolescents from both underestimation (only in girls) and overestimation in the total sample (OR 0.74, 95%CI 0.68–0.81) and both genders. BAME increased this risk of overestimation in both genders (OR = 1.83, 95%CI 1.67–2.0), and the risk of underestimation among boys. Conclusions: Prevention programmes should include a wide range of psychosocial factors to improve BWC among adolescents.