A School‐Based Nutrition and Physical Activity Intervention for the Prevention of Childhood Obesity: Study Design and Baseline Findings From a Cluster‐Randomized Trial

This manuscript describes the design and baseline findings of the POI trial, a school‐based, cluster‐randomized intervention aimed at the prevention of childhood obesity in the Canary Islands, Spain. Childhood obesity prevalence in this region is among the highest in Europe, with 40.6% of children aged 6–9 years classified as overweight or obese. Early, multidisciplinary, school‐based interventions integrating nutrition and physical activity are therefore a public health priority. Methods The POI trial is a cluster‐randomized controlled study conducted in primary schools in Gran Canaria, enrolling children aged 6–10 years. The intervention integrates nutrition education, physical activity promotion, and family engagement, supported by both paper‐based and digital educational materials. Teachers played a central role in intervention delivery within the classroom setting. Schools served as the unit of randomization and implementation. Baseline assessments included standardized anthropometric measurements, objectively measured physical activity, and selected metabolic parameters (fasting glucose and lipid profile). Dietary intake outcomes will be reported separately; this manuscript focuses on the nutrition education framework and baseline nutrition‐related metabolic indicators. Results A total of 557 children from 13 schools were included (298 intervention participants from 5 schools and 259 controls from 8 schools). Significant differences in overweight and obesity prevalence were observed by school type, with the highest prevalence in public schools (48.6%), followed by partially subsidized (33.2%) and private schools (28.3%) ( p = 0.001). Among participants with available blood samples ( n = 237), elevated fasting glucose was detected in 21 children and hypercholesterolemia in 24 children. Conclusions These baseline findings highlight substantial socioeconomic disparities in childhood overweight and obesity and demonstrate the presence of early metabolic risk in school‐aged children. The POI trial provides a scalable, school‐based model integrating nutrition education and physical activity for obesity prevention, with the potential to inform public health strategies in high‐prevalence settings. Trial Registration: ClinicalTrials.gov identifier: NCT06607159