Introduction: The 40X40 training program promotes sports in Bogotá. This strategy requires a diagnosis of population based on anthropometric nutritional status through the Zscore body mass index (BMI) (1) to promote healthy habits. Objective: To determine the characteristics of BMI in school children enrolled in the 40X40 Program in Bogotá. Materials and methods: Research with a quantitative approach and descriptive study, regarding anthropometric variables and socio-demographic characteristics. Results: 1 035 school children participated, including 564 women and 471 men. 18 public educational institutions, in 10 localities, and 17 sports were included: ball 31%, combat 28%, art and pressure 16%, time 23% time, and urban sports and new trends (DUNT for its acronym in Spanish) 2%. Variables measuring weight, height and BMI and BMIzscore were considered. BMI showed 38.2% underweight, 46.2% average weight, 12.2% overweight and 2.8% obese children, while BMIzscore reported 16.5% underweight, 79.8% average, 3.5% overweight and 0.2% obese children. Conclusions: Significant differences between BMI and BMIzscore were reported; the first shows weight and height and the second adjusts both variables plus age. Therefore, it was determined that BMIzscore evaluates comprehensively the process of growth and development.