Background: Childhood obesity is increasing around the world. Compared with developed countries, the rate of increase is 30% higher in developing countries, where the monitoring of obesity and overweight is essential. This study investigated the prevalence of obesity, overweight, thinness, and stunting in primary school students in Shahroud, Iran.

Methods: A total of 5,620 primary students were enrolled during 2015. In rural areas all students were invited to participate, while cluster sampling was used in urban areas and 200 classrooms were selected randomly as clusters. Height, weight and body mass index Z-scores for age (HAZ, WAZ and BAZ) were calculated based on World Health Organization standard. The mean indices and prevalence of obesity, overweight, thinness, and stunting were calculated by education level, gender, and place of residence. Prevalence of obesity and overweight was estimated also by international obesity task force definition.

Results: The mean WAZ, HAZ, and BAZ were 0.050 ± 1.25, 0.005 ± 0.98, and 0.076 ± 1.35, respectively. These indices in rural areas were significantly lower than those in urban areas (P < 0.001). Overall, 25.7% of children in urban areas (95%CI: 24.1-27.4) and 14.8% in rural areas (95%CI: 12.3-17.3) were overweight or obese, and 5.1% of rural girls (95%CI: 3.1-7.0) were stunted.

Conclusions: Compared with previous studies, obesity and overweight are still rising in Iranian school children, thus more serious interventions are needed. These interventions must also deal with underweight and stunting, particularly in rural areas.