the study of obesity and overweight in arak primary school students, 2009

background: the prevalence of obesity and overweight among children and adolescents is increasing worldwide and it is one of the most important general health problems. one of the routine methods in diagnosis of physical growth in children is body mass index (bmi). methods: this study is a cross – sectional one in which 742 students from primary schools aged 7-11 years were chosen in a two-stage cluster sampling by considering their gender and age. weight and height of students were collected and their body mass index (bmi) was also calculated. bmi percentiles of these students were compared with the iranian reference (husseini) and the center of disease control and prevention (cdc) reference data. for statistical analysis t-test was used to compare data. results: the prevalence rates of obesity on the base of iranian reference and cdc were estimated 4.5%, 1.7% (p <0.001), respectively, and the prevalence of overweight were 8.7%, 4% respectively (p < 0.01). considering the prevalence of overweight, there was no statistically difference between girls and boys while, prevalence of obesity based on iranian reference in both gender was statistically different (p=0.046). the overall prevalence of obesity and overweight based on iranian reference was significantly higher than that of the cdc reference (p <0.001). conclusion: the prevalence rate of obesity and overweight based on cdc was acceptable. as the results of different references the prevalence of obesity were not the same, so the employment of relevant bmi percentile and further studies to determine the effect size of various factors affecting weight and height are recommended.