The Relationship between Relative BMI Change and Height Growth among Overweight Children

Son, Young Woo; Lee, Kayoung; Jeon, Young Bae

Abstract

BACKGROUND
Many parents of overweight children have believed that their children's weight may be lost with the increase of their height. The purpose of this 2-year prospective study was to examine whether such belief is valid. METHODS: A total of 190 children (113 boys and 77 girls) aged 6-11 years who were overweight (BMI > 85th percentile of age and gender-specific 1999 Korean children standard) from two elementary schools were the subjects. Their height and weight were measured again after 2 years. Children and their parents completed questionnaires on eating habits and physical activity, and their attitude on weight in the beginning of study. Children's weight status was evaluated using relative BMI. RESULTS: Children's baseline relative BMI was 134.9 +/- 13.8%. About 60% of the children reported weight loss attempt and 49% of their parents tried to persuade their child to lose weight. Children's BMI increased by 1.6 +/- 2.1 kg/m2 and their relative BMI decreased by 1.2 +/- 12.1% over 2 years. While children's eating habits and physical activity, and their attitude on the child's weight were not related to the 2-year relative BMI change, the child's age, gender, baseline relative BMI, and the 2-year height change were associated with the 2-year relative BMI change (R2 = 0.15, P < 0.001). The 2-year relative BMI increased with the 2-year height increase after controlling for the three predictors (B = 0.86, SE = 0.28, P = 0.002). CONCLUSION: We found the 2-year height change positively associated with the 2-year relative BMI change among school-aged overweight children. Then, the belief that children's weight status may be improved with the increase of their height should be denied.