64 Child eating behaviours and zBMI during the COVID-19 pandemic in Canada: A prospective cohort study

Abstract Background The COVID-19 pandemic was associated with increased body weight and obesity rates in children, but the underlying mechanisms driving these changes are not understood. Few studies have evaluated the impact of child eating behaviours on body mass index during the pandemic. Objectives To determine whether eating behaviours during the COVID-19 pandemic (overeating, difficulty getting into an eating routine, undereating, picky eating, and mealtime screen use) were associated with age- and sex-standardized body mass index (zBMI) in Canadian children. Design/Methods A prospective cohort study was conducted with children age 1-12y participating in the TARGet Kids! COVID-19 Study for Children and Families, a practice-based research network in Canada. Eating behaviours were assessed using biweekly questionnaires from March 2020-April 2023. Height and weight were measured at primary care office visits or by parents at home using standardized instructions. Linear mixed effects models accounting for repeated measures were used to explore the association between child eating behaviours and zBMI during the pandemic. All models were adjusted for covariates identified a priori, including child age, sex, birthweight, maternal ethnicity, maternal BMI, family income, and zBMI measurement method. Results A total of 330 children (548 observations) were included in the study, with a mean age 6.4 ± 2.9 years, and 52% female. Overeating was positively associated with higher mean zBMI (overall p=0.0005). Children who ‘often’ overate during the pandemic had higher zBMI (1.09 units; 95%CI 0.36,1.82) compared with those who ‘never’ overate (0.17 units; 95%CI -0.30,0.63; p=0.004). Difficulty getting into an eating routine was associated with higher mean zBMI (overall p=0.009), with those who ‘often’ had difficulties getting into an eating routine having higher zBMI (1.08 units; 95%CI 0.38,1.78) compared to those who ‘never’ had difficulty (0.44 units; 95% CI -0.04,0.92; p=0.008). Mealtime screen use was also associated with higher mean zBMI (p=0.04), with each additional meal consumed with a screen device per day being associated with a 0.13 unit (95% CI 0.003,0.25) higher zBMI. There were no statistically significant differences in zBMI between response categories for picky eating and undereating. Conclusion Overeating, difficulty getting into an eating routine and mealtime screen use were associated with increased zBMI in children during the COVID-19 pandemic. Such eating behaviours represent targets for interventions that aim to mitigate the adverse health impacts of future pandemics on children. Potential competing interests JJ - consultant work for Nutrigenomix Inc, a University of Toronto start-up which offers evidence-based genetic testing for personalized nutrition. Consulting work terminated July 1, 2023. This relationship is unrelated to the work submitted.