Self-reported weight and predictors of missing responses in youth.

Objective: The aims of the present manuscript are to analyse self-reported data on weight, including the missing data, from the 2014 Scottish Health Behaviour in School-Aged Children (HBSC) Study, and to investigate whether behavioural factors related with overweight and obesity, namely dietary habits, physical activity and sedentary behaviour, are associated with weight non-response.

Research Methods & Procedures: 10839 11-, 13- and 15-year-olds participated in the cross-national 2014 Scottish HBSC Study. Weight missing data was evaluated using Little's Missing Completely at Random (MCAR) test. Afterwards, a fitted multivariate logistic regression model was used to determine all possible multivariate associations between weight response and each of the behavioural factors related with obesity.

Results: 58.9% of self-reported weight was missing, not at random (MCAR p < 0.001). Weight was self-reported less frequently by girls (19.2%) than by boys (21.9%). Participants who reported low physical activity (OR 1.2, p < 0.001), low vegetable consumption (OR 1.24, p < 0.001) and high computer gaming on weekdays (OR 1.18, p = 0.003) were more likely to not report their weight.

Conclusions: There are groups of young people in Scotland who are less likely to report their weight. Their weight status may be of the greatest concern because of their poorer health profile, based on key behaviours associated with their non-response. Furthermore, knowing the value of a healthy weight and reinforcing healthy lifestyle messages may help raise youth awareness of how diet, physical activity and sedentary behaviours can influence weight.