RESUMEN
Early childhood is a critical period for obesity prevention. This randomized controlled study evaluated the effectiveness of an educational intervention preventing obesity in preschool-age children. A nutritional education intervention, with a follow-up session one year later, was conducted with parents of children aged 3 to 4 years of public schools in the province of Málaga. The main outcome variable was the body mass index z-score (zBMI). The prevalence of overweight or obesity was the secondary outcome variable. The sample comprised 261 students (control group = 139). Initial BMI, weight, height-for-age and prevalence of overweight and obesity were similar for both groups. After the first year of the intervention, the zBMI of the intervention group decreased significantly from 0.23 to 0.10 (p = 0.002), and the subgroup of patients with baseline zBMI above the median decreased from 1 to 0.72 (p = 0.001), and in the second year from 1.01 to 0.73 (p = 0.002). The joint prevalence of overweight and obesity increased in the control group (12.2% to 20.1%; p = 0.027), while in the intervention group, there were no significant changes. This preschool educational intervention with parents improved their children's BMI, especially those with a higher BMI for their age, and favored the prevention of overweight or obesity.