BMI categories by year, by age.

Reports from many settings suggest that pediatric overweight and obesity increased in 2020 and 2021, presumably due to lifestyle changes associated with the COVID-19 pandemic. Many of these previous reports have relied on convenience samples or subsets of the population. Here, we present results of a longitudinal study of the entire population of Israel, a nation of approximately 9 million people, with the proportion with underweight, normal weight, overweight, and obesity at age 7 and at age 14–15, across the years 2017–2021. Our results show that the prevalence of overweight and obesity, which had been steady or improving through 2019, increased relatively quickly in 2020 and 2021. For example, among 7-year-olds, the percentage of children with obesity in 2019 was 6.8% (99% CI: 6.69–7.05), and by 2021, it had increased to 7.7% (99% CI: 7.53–7.93). There were important disparities in overweight and obesity based on SES; for example, the rate ratio for obesity comparing the poorest with the wealthiest 14–15-year-olds in 2019 was 1.63 (99% CI: 1.55–1.72). However, these disparities did not change meaningfully in 2020 and 2021, implying that while obesity did become more prevalent, this increase in prevalence was not differential across socioeconomic status. Like many other nations, Israel too experienced considerable increases in pediatric overweight and obesity in 2020–2021, erasing the improvements of the previous years among younger children.