Karnebeek K, et al. - In this cross-sectional analysis, researchers assessed the prevalence of comorbidities in school-age children with obesity and compared its prevalence and the impact of a lifestyle intervention between children in primary and secondary school and between boys and girls. In 149 primary and 150 secondary school children with obesity (162 girls), comorbidities were assessed. In 82 elementary and 75 secondary school children, the effect of lifestyle intervention was studied. In primary school children with obesity, the presence of comorbidities is already evident. In primary compared to secondary school children, the effect of lifestyle intervention on these comorbidities is greater, emphasizing the need for early intervention.