The World Obesity Federation estimates that obesity affects 206 million children by the age of 5. The prevalence of overweight or obesity among children aged 3 to 5 years between 2017 and 2020 in southern France was estimated at 11.7%, reaching 16% in three disadvantaged districts.

The objective of this study was to assess the prevalence rates of overweight and obesity among children aged 3 to 5 years during the 2022–2023 school year in the department of Bouches-du-Rhône (southern France), with a focus on 3 districts with higher rates where local initiatives to prevent obesity have since been developed.

This descriptive, cross-sectional study included nursery school children who received full systematic health checks during the 2022–2023 school year. Body mass index (BMI) z scores were calculated using International Obesity Task Force references. Data on the French deprivation (FDep) index for each school district were collected to allow assessment of the impact of social inequalities. Chi-square tests were used to evaluate the associations of overweight and obesity rates with sex and school area.

A total of 13,454 children (mean age: 48 months; mean Z score (BMI): -0.05 ± 1.16) were included. The prevalence of overweight was 8.5% (95% CI [7.6;9.3]), and the prevalence of obesity was 2.5% (95% CI [1.6;3.3]). There was a significant female predominance for overweight (9.7%, 95% CI [8.5;10.9] vs. 7.2%, 95% CI [6.0;8.4]; p<0.001 ). The prevalence of overweight increased with increasing FDep index and reached 11.4% in the 3 disadvantaged districts in which local initiatives for preventing obesity have since been developed. The prevalence of obesity was higher in these districts than in the department as a whole (4.5% vs. 2.5%, p<0.001 ).

The postpandemic prevalence rates of overweight and obesity remained stable but were associated with a significant female predominance and indicated impacts of social inequality.