[Evolution of weight and body mass index in the child population of Almagro (Ciudad Real, Spain) in the last 12 years and the impact of the COVID-19 pandemic].

Introduction: the prevalence of childhood overweight and obesity has steadily increased over the past two decades, both in Spain and globally. The COVID-19 pandemic disrupted lifestyles, impacting children's diet and physical activity. Objective: we retrospectively analyzed the evolution of weight and BMI (body mass index) in 563 children aged 4 to 14 years, comparing three periods: pre-pandemic (until 2019), pandemic (2021-2022), and post-pandemic (2023-2024). Results: before 2020, a significant weight gain trend was already present: weight Z-scores increased by +0.21 SD (standard deviations) between the ages of 4 and 6. The lockdown drastically accelerated weight gain; weight Z-scores increased by up to +0.41 SD between the ages of 4 and 6 in the immediate post-lockdown phase, nearly doubling the baseline trend. Two years later, in the late post-pandemic phase, a partial reduction in weight was observed (-0.20 SD at age 14), indicating that weight gain has not been fully reversed. The consolidation of excess weight was also found: the combined rates of overweight and obesity (BMI Z-score > +1 SD) had increased: 42.2 % at age 12 and 40.5 % at age 14. Conclusions: a significant weight gain was observed during the pandemic, especially in younger children, with partial persistence. The sustained increase in overweight and obesity rates highlights the urgent need for preventive strategies and monitoring of lifestyle habits in the pediatric population.