COVID-19 impact on overweight and obesity rates in Aotearoa | New Zealand 4-year-old children

Background: COVID-19 has had profound societal impacts. This study estimated overweight, obesity, and extreme obesity rates in 4-year-old children over pre- and post-COVID-19 periods, and investigated differential changes between sex, ethnic and deprivation groups.Methods: A national screening programme of 4-year-old children undertaking B4 School Checks (B4SCs) between 1 January 2010 and 7 March 2023 was analysed. B4SCs include anthropometric measurements enabling sex-specific body mass index-for-age Z-scores (BMI z-scores) to be derived. Children with >= 85th, >= 95th, and >= 99.7th percentile BMI z-scores were classified as overweight, obese, and extremely obese.Results: The eligible sample included 656,038 children (48.8% girls). Overall, 210,492 (32.1%) children were overweight, 95,196 (14.5%) obese, and 19,926 (3.0%) extremely obese. While decreasing in the pre-COVID-19 period, annual prevalence estimates for overweight, obese, and extremely obese significantly (all p < 0.001) increased in the year after COVID-restrictions were implemented. However, after three years, overweight and obese prevalence estimates were no different to pre-COVID levels overall or stratified by sex for ethnicity and deprivation groups. Extreme obesity prevalence estimates also decreased but remained higher than pre-COVID levels.Conclusion: The sharp and steep increases in prevalence estimates all dampened relatively quickly. The question remains whether these rates will continue to decrease in time.