Relation of intelligence quotient and body mass index in preschool children: a community-based cross-sectional study

OBJECTIVE: Overweight and obesity in children is a global problem. Besides physical effects, obesity has harmful psychological effects on children. METHODS: We carried out cross-sectional community-based study to investigate the relation between body mass index (BMI) and cognitive functioning in preschool children. Thirteen socioeconomical elements of 1151 children were measured and analyzed based on their intelligence quotient (IQ) test results. Thirteen out of 33 provinces were selected randomly, and schools were selected as clusters in rural and urban areas. Descriptive statistics, t-test, analysis of variance and regression were used when appropriate. RESULTS: Our analysis showed that IQ was associated with household income, place of residence, delivery type, type of infant feeding and father's and mother's education level (P<0.001 for all). Using penalized linear regression for eliminating the impact of confounding factor, our study shows that, living in metropolitan (β=2.411) and urban areas (β=2.761), the level of participants' father's education (β=5.251) was positively and BMI (β=−0.594) was negatively related with IQ test results. CONCLUSIONS: The findings of the present study showed that a lower IQ score is associated with higher BMI. However, this relation appears to be largely mediated when the socioeconomic status was considered