Association of Weight Control Behaviors with Body Mass Index in Korean Adolescents: A Quantile Regression Approach.

PURPOSE: Adolescents are interested in weight control but likely practice unhealthy weight control behaviors. This study aimed to examine weight control behaviors associated with body mass index (BMI) in Korean adolescents.

DESIGN AND METHODS: In this descriptive cross-sectional study of 16- to 19-year-old adolescents (97 girls and 90 boys), analyses were conducted of physical activity, sedentary behaviors, dietary behaviors, and self-efficacy for physical activity and diet. Daily steps were measured using pedometers. Height and weight were self-reported. We conducted descriptive statistics and quantile regression analysis using STATA 14.0.

RESULTS: About 10% were underweight, and 8.6% overweight and obese. Average weekday and weekend steps/day were <10,000. Only 4.3% reported performing moderate-to-vigorous physical activity (MVPA) daily. Less than half (42.5%) reported that they had three meals/day every day. Most (89.3%) had milk less than once/day. Quantile regression showed that, for the 5th BMI percentile group, (1) age (β = 0.941) and milk consumption (β = 2.148) were significantly positively associated with BMI, whereas (2) dietary self-efficacy (β = -0.083) was significantly negatively associated with BMI. For the 95th percentile group, having three meals/day (β = 2.558) was significantly positively associated with BMI, whereas MVPA (β = -5.440) and muscle-strengthening exercise (β = -3.392) were significantly negatively associated with BMI.

CONCLUSIONS: Milk consumption was positively associated with BMI of underweight adolescents, whereas physical activities were negatively associated with BMI of overweight and obese adolescents.

PRACTICE IMPLICATION: Weight control programs for adolescents may need to be tailored for differing BMI levels.