Ultra-processed food intake and risk of obesity among schoolchildren aged 8-12 years living in Victoria, Australia.

Introduction: Ultra-processed foods (UPF) are frequently consumed by children, possibly contributing to childhood obesity. It is unknown if UPF consumption among Australian children differentiates by sociodemographic factors.

Objectives: To describe schoolchildren's intake of UPF across sexes, age, geographic location and socioeconomic status (SES). To analyse associations between UPF intake and indicators of obesity.

Methods: UPF consumption of children aged 8-12 years in Victoria (Australia) was examined using 24-h dietary-recall data classified by the NOVA system. UPF intake was compared across sociodemographic groups. Regression analysis explored the association between UPF intake and BMI z-score, overweight/obesity and abdominal obesity.

Results: UPF comprised 47.2% of total energy intake (range 23.7%-72.2%), with no significant differences across sex, age group (8-9 vs. 10-12 years), geographic location or SES. Including all children, there were no associations between UPF intake and obesity indicators. In age-stratified models, among children aged 10-12 years, a 10% increment in the proportion of UPF in the diet (% g/day) was significantly associated with a 0.07 (95% CI 0.01, 0.12) higher body mass index (BMI) z-score and a 19% (odds ratio 1.19, 95% CI 1.07, 1.33) increase in the odds of central obesity. No associations between UPF intake and indicators of obesity were found in the younger 8- to 9-year-old group.

Conclusions: UPF contributed greatly to the dietary intake of primary schoolchildren. Among older children, higher intake of UPF was associated with higher BMI z-score and central adiposity. Further longitudinal research in Australian pediatric samples to understand UPF impact upon adiposity outcomes across different stages of childhood is needed.