Associations between BMI, body size perception, and dropout from upper secondary education: A prospective cohort study of 15–19-year-old adolescents

Purpose: To examine the independent associations of BMI and body size perception with dropout from upper secondary education.

Methods: Data from the Danish National Youth Study 2014, including 63,976 students aged 15-19 years, were linked to information on school dropout from the Student Register. Multilevel logistic regressions were employed to examine how BMI and body size perception were each associated with school dropout. Mediation analyses were conducted to assess the role of body size perception in the BMI-dropout association.

Results: Both low and high BMI were associated with higher odds of school dropout, following a U-shaped pattern across the BMI continuum. For instance, females with a BMI above 30 kg/m2 had an OR of 2.37 (95 % CI: 1.74;3.27), compared to those with a BMI of 18.5-24.9 kg/m2. Adjusting for body size perception, ORs attenuated for students with a BMI above the median. Body size perception mediated a substantial proportion of the BMI-dropout association. Students who perceived themselves as too thin or fat also had higher odds of dropout. For instance, females who perceived themselves as 'much too fat' had an OR of 2.66 (95 % CI: 2.17;3.25), compared to those who perceived themselves as 'about right size'. Adjusting for BMI had only minor impact on ORs.

Conclusion: Low and high BMI, as well as the perception of not being the right size, were associated with higher odds of dropout from upper secondary education. Adjusted for body size perception, the association between BMI and dropout attenuated, suggesting that body size perception plays a crucial role in this relationship. Body size perception partly explains the BMI-dropout relationship, highlighting a need for more comprehensive approaches focusing adolescents' perceptions of their bodies alongside actual weight to reduce school dropout.