Background: between 1999 and 2022, the prevalence of overweight and obesity (OW + Ob) in adults increased by more than 20 % in 45 countries, a trend also reflected in the rise of obesity among children and adolescents in 186 countries.

Objective: to compare OW + Ob in the population aged 5 to 11 years over different periods using the polynomial index of overweight and obesity (IPSO).

Methods: cross-sectional anthropometric data from children aged 5-11 years were analyzed using information from the 1999 National Nutrition Survey, the National Health and Nutrition Surveys (ENSANUT 2006-2022), and the National Weight and Height Registry (RNPT 2015-2018). Z-scores for BMI-for-age were calculated based on WHO standards. Means for age and Z-scores were estimated for all ages (60-144 months) across seven intervals. T-SQL scripts were developed to obtain a polynomial regression model and an integral to calculate IPSO values, which were graphically represented.

Results: IPSO60-144 increased from 32.5 in 1999 to 50.1 in 2006 and 53.1 in 2022, showing increases across all analyzed age intervals. The RNPT highlighted differences by sex (27.62 for girls vs. 41.57 for boys) and socioeconomic level.

Conclusions: IPSO is useful for historical analysis and monitoring the magnitude of obesity in future research, as it enables visualization of OW + Ob trends in school-aged children. It is a key tool for guiding interventions and public policy proposals aimed at reducing OW + Ob in childhood.