School performance and weight status of children and young adolescents in a transitional society in Thailand

OBJECTIVE: To study the association between current or previous weight stat us and school performance among children and young adolescents of Hat Yai m unicipality, southern Thailand. DESIGN: Cross-sectional and longitudinal study SETTING: Primary and secondary schools of Hat Yai municipality, southern Th ailand. SUBJECTS: 1207 grades 3-6 and 587 grades 7-9 students. MEASUREMENTS: Body mass index (BMI, kg/m(2)) calculated from weight and hei ght measurement of subjects in 1992 and 1994; parental education level and occupation, and monthly income, by questionnaire performed in 1992; grade-p oint-average (GPA) and grades of mathematics and Thai language from the sch ool records of final examinations in 1994. RESULTS: Overweight subjects (BMI value > 85th percentile of the NHANES-I d ata for age and gender) in grades 7-9 had a mean GPA 0.20 point (95% confid ence internal (CI) = 0.04, 0.37) lower than that of the normal weight child ren after controlling for gender, age, school and grade. They were twice mo re likely to have low grades (lower than 2 on the scales of 0-4) of mathema tics and Thai language than normal weight children. There were no associati ons between GPA or individual subject grades and previous BMI status in 199 2, Children in grades 7-9 who became overweight over the two years, had a m ean GPA of 0.88 point Tower than those who did not become overweight (95% C I=0.12, 0.84), In grades 3-6 subjects, however, becoming overweight had no effect on GPA and individual subject scores. CONCLUSIONS: Our study showed that being overweight and becoming overweight during adolescence (grades 7-9) was associated with poor school performanc e, whereas such an association did not exist in children (grades 3-6).