Are weight-related attitudes and behaviours associated with the accuracy of BMI derived from self-reported weight and height among 13-year-olds?

Abstract

The aim was to explore the association between weight-related attitudes and behaviours and the accuracy of body mass index (BMI) derived from self-reported weight and height. A total of 828 adolescents from the Health In Adolescents study were included. Self-reported and objective weight and height data were collected, and BMI was computed. Information about weight-related attitudes and behaviours was obtained. The association between weight-related attitudes and behaviours and the difference between BMI computed from self-reported and objective measures was assessed using generalized linear mixed model analyses. BMI was under-reported by overweight girls (p<0.001) and boys (p<0.001) compared to their normal weight counterparts. Underweight girls on the other hand over-reported their BMI (p=0.002). Girls who reported trying to lose weight under-reported their BMI compared to girls who had not tried to do anything about their weight (p=0.02). Girls who perceived their weight as being too much under-reported their BMI compared to girls who thought their weight was ok, the association was however borderline significant (p=0.06); this association was also found among boys (p=0.03). Self-weighing and the reported importance of weight for how adolescents perceive themselves were not associated with the accuracy of BMI. weight perception and weight control behaviour among girls only were related to the accuracy of self-reported BMI; no association was found with self-weighing behaviour and the perceived importance of weight for how adolescents perceive themselves. Knowledge of such factors will allow for a better interpretation and possibly adjustment/correction of results of surveys based on self-reported weight and height data.