Assessing Overweight in School Going Children: A Simplified Formula

Background: The International Obesity Task Force (IOTF) has developed new cut-offs for defining overweight and obesity in children. The cut-offs have been developed for children 2-18 years of age. Objective: To develop a simplified formula for rapid assessment of overweight in school going children. Methods: We used the extended IOTF standards used for assessment of overweight and obesity among school going children. We plotted the Body Mass Index (BMI) at level 25, developed by IOTF as the cut-off for defining overweight among children, against age in months. Scatter plots and simple linear regression was used to develop a simplified formula for the relationship between age in months and the IOTF BMI cut-off for overweight. Correlation coefficients and R2 values were used to choose an appropriate simplified formula. Results: Age in months and IOTF BMI cut-offs are linearly related from age six to 18 years. The trend is more linear in boys. Girls show a more or less ‘S’ shaped relationship compared to boys where the relationship is ‘J’ shaped. The simplified formula developed has a higher correlation coefficient for boys as compared to girls. Conclusion: The simplified formula can be easily used in field settings for rapid assessment of overweight among school children, in absence of IOTF cut-offs. Further studies are warranted to estimate the validity of these formulae under field settings.