Secular trends in height, weight and obesity among Korean children and adolescents in 2006-2015

Trends in Obesity and Obesity-Related Risk Factors among Adolescents in Korea from 2009 to 2019

This study was conducted to identify the trends in obesity prevalence among adolescents and changes in the risk factors related to obesity. The study analyzed secondary data obtained from Korean Youth Risk Behavior Web-based Surveys conducted from 2009 to 2019. The Korean Youth Risk Behavior Web-based Survey is an annual survey of a nationwide representative sample of enrolled students aged 13–18 years in middle and high schools in Korea. Linear and trend analyses showed that the prevalence of obesity increased by 0.47% on average annually; this increase was statistically significant. Healthy food intake decreased significantly, but the prevalence of unhealthy food intake and the prevalence of skipping breakfast increased significantly. Vigorous-intensity physical activity, physical activity for over 60 min a day, and muscle-strengthening exercise for more than 3 days a week increased significantly, but so did the adolescents’ sedentary time. Therefore, health care providers and public policymakers need to actively manage adolescent obesity, which has been continuously increasing since 2009. In addition, long-term trends in obesity-related risk factors such as physical activity and dietary behaviors need to be considered in the development of obesity management strategies.

Regional Adolescent Obesity and Overweight Status in Korea from 2018-2019: Comparison between Two Data Sources

Difference in the regional adolescent obesity level may cause a notable health inequality between regions since it significantly affects adulthood health status. This study examined 2018 and 2019 regional obesity and overweight status of adolescents aged 12 to 18 by comparing two cross sectional population-based data sources, the Korea Youth Risk Behavior Web-based Survey (KYRBS) and the National Student Health Examination (NSHE). Prevalence was estimated by calculating weighted percentages and 95% confidence intervals. Correlations in the relative rankings of each municipality were determined by computing Spearman correlation coefficients (r_s), and prevalence discrepancies between the data sources were visualized by simple correlation graphs. The geographical distributions of adolescent obesity and overweight status showed no perfect concordances between the data sources regardless of sexes and survey years. For adolescent obesity status, there were significant difference between the least and the most obese regions and r_s levels were fair to good with p-values less than 0.05, but the correlation graphs indicated body mass index (BMI) underreporting in the KYRBS. For adolescent overweight status, no significant similarities were defined between the data. These results can be used as a basis for the establishment of related policies.

Parental Factors Associated with Obesity in Korean Adolescents

Parental characteristics can influence adolescent obesity. However, the influence of parental characteristics on obesity may differ depending on the adolescent’s sex. This study evaluated parental characteristics that were associated with obesity in male and female adolescents. This study involved the secondary data analysis of cross-sectional survey data that were collected from June to September 2015. The study subjects included 1621 eighth-grade students. The study variables included sex, age, body mass index, household income, parental weight, parental perceptions of the child’s body, parental lifestyle, and parental social support for healthy eating and physical activity. The association between parental factors and adolescent obesity was analyzed via logistic regression analysis for each sex. Among male students, the fathers’ and mothers’ overweight status, fathers’ underestimation and overestimation of male adolescent weight, mothers’ dietary habits, and the mothers’ physical activity level were identified as obesity-associated factors. Among female students, the mothers’ overweight status, underestimation of female adolescent weight by fathers, dietary habits, and the physical activity level of fathers were significantly associated with adolescent obesity. The mothers’ overweight status and the underestimation of weight by fathers were strongly associated with obesity in male and female adolescents. Parental involvement in obesity-intervention programs could help prevent adolescent obesity.

Trends in Dietary Intake of Total Fat and Fatty Acids Among Korean Adolescents from 2007 to 2017

We analyzed the trends in dietary intake of total fat and fatty acids among Korean adolescents during 2007-2017. A total of 6406 adolescents from the 2007-2017 Korea National Health and Examination Surveys were selected. Total fat and fatty acids intakes were calculated based on single 24-hour recall data and presented as grams (g) and percentage of energy intake (% kcal) across the survey period. Linear trends in intake across the survey period were compared using the multiple regression model. Total fat intake increased during the 11-year period from 54.3 g (21.7% kcal) to 61.8 g (25.2% kcal). Saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) intakes changed from 17.8 g (7.1% kcal) and 17.2 g (6.8% kcal) to 20.6 g (8.4% kcal) and 20.7 g (8.4% kcal) over time, respectively. For polyunsaturated fatty acids (PUFA), n-3 fatty acid intake did not change during the survey period. The proportions of individuals who had total fat and SFA above the recommendations increased across the survey period: 13.7% to 27.5% for total fat and 36.0% to 49.7% for SFA. Among Korean adolescents, dietary fat intake increased over time and the increases in SFA and MUFA intake were prominent. Monitoring dietary fat intake is helpful to suggest dietary guidelines and health policies.

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.