Introduction: The sensitivity and specificity of waist circumference as an independent predictor of non-communicable diseases in young people have been demonstrated. This study aimed at comparing changes in waist circumference of Tehranian children and adolescents over a 3-year interval. Materials and Methods: Height, weight and waist circumference of children (3-10 years) and adolescents (11-19 years) of district 13 of Tehran were measured twice; in 1999 (n=3922) and in 2001 (n=1026,) within the framework of phases 1 and 2 of the Tehran Lipid and Glucose Study (TLGS). BMI was calculated dividing weight (in kg) by height square (in m2). Children and adolescents with BMIs of 25 and 30, at the age of 18 years, were considered overweight and obese, respectively, based on international curves.
Results: Mean of waist circumference in male subjects at the ages of 5. 5, 6. 5, 11, 12, 16. 5(p<0. 05), 10, 13. 5 (p<0. 01), 15. 5 and 16 (p<0. 001) years old in the second phase of TLGS was significantly higher than that in first phase. In contrast, among female subjects, only in the 10-year olds, waist circumference was higher than that of the first phase (p<0. 05). Mean of BMI showed increase in 8. 5 and 18 year old males and 10, 13. 5, 15 and 16-year-old females (p<0. 05). Prevalence of overweight and obesity (based on BMI) was significantly higher only in females in the second phase as compared to that of the first phase (p<0. 05).
Conclusion: In Tehranian male children and adolescents, waist circumference, as an indicator of central obesity, increased more than BMI over a 3-year interval. In females however, prevalence of overweight and obesity based on BMI increased more than central obesity. Urgent action is needed to reverse the trends and reduce the likely resulting medical and psychological costs that can be caused by the increase in obesity among young people.