When does obesity begin in northern Iranian children?

Background: identifying the onset of obesity in children can be helpful to design the prevention programs for obesity and its complications. the aim of this study was to evaluate the onset of obesity in children. methods: this cross-sectional study was conducted on the first grade of primary school children in sari (urban areas) (mazandaran province, iran) in 2014. the names and contact information of the first grade of primary school children (6–7 years old) were obtained through referring to sari health center (schools health unit). the onset of obesity was identified and recorded based on a body mass index (bmi) higher than 95% (for age and gender) and the weight/age and height/age centers for disease control and prevention (cdc) growth charts which were available in the child health records. results: there were 127 obese children (71 boys, 56 girls) in the current study. the mean weight, height and bmi of children were 32.63±4.918 (kg), 123.02±5.166 (cm) and 21.52±2.369 (kg/m^2), respectively. furthermore the chance of obesity increased as the child grew up and there was an upward trend from 3 to 6 years old. conclusions: according to the results the obesity frequency remains high; thus, it is important to pay special attention toward children's weight gain during this period even if it is not within the overweight/obesity range.