Factors Related to Body Mass Index and Body Mass Index Change in Korean Children: Preliminary Results from the Obesity and Metabolic Disorders Cohort in Childhood

BACKGROUND: This preliminary study is to assess risk factors associated with children's body mass index (BMI) and their changes over a 2-year period based on the analysis of the Obesity and Metabolic Disorders Cohort in Childhood registry. METHODS: A total of 1,504 children comprised of 474 1st graders and 1,030 4th graders were included in the study. Data on physical activity, dietary intake, and socioeconomic status were obtained through self-administered questionnaires, and height and weight were measured annually for 2 years. RESULTS: In a cross-sectional analysis, BMI of 1st graders was associated with higher parental BMI (both P < 0.001) and frequent snack consumption (P = 0.049). BMI of 4th graders was additionally associated with shorter sleep duration (P = 0.001), lower household income (P = 0.016), higher fat intake (P = 0.017), and frequent meal skipping (P = 0.020). During a 2-year follow-up, BMI increased by 0.8 ± 1.4 kg/m(2) in 1st graders and by 1.3 ± 1.4 kg/m(2) in 4th graders. In a longitudinal analysis, higher exercise frequency (P = 0.007), shorter sleep duration (P = 0.027), lower household income (P = 0.002), and higher paternal BMI (P = 0.002, 0.043) were significant predictors of BMI changes in the 1st graders whereas only higher maternal BMI (P=0.035), and frequent snack consumption (P = 0.010) were predictors for the 4th graders BMI changes. CONCLUSION: Our findings indicate that parental obesity, short sleep duration, low socioeconomic status, and frequent snacking are associated with BMI and BMI changes.