Leisure-time and study-time Internet use and dietary risk factors in Korean adolescents

Prolonged screen time is associated with an increased risk of obesity in adolescents. However, little is known about whether Internet use is also associated with dietary risk factors including consumption of obesogenic foods. In this study, we examined the associations of leisure-time and study-time Internet use with dietary risk factors in Korean adolescents using nationally representative survey data. We conducted a cross-sectional analysis among 54,416 middle and high school students in the Korea Youth Risk Behavior Web-based Survey 2015. Participants were asked to report the average duration of leisure-time and study-time Internet use, days of skipping breakfast, and frequency of fruit, vegetable, instant noodle, fast-food, chip/cracker, and sugar-sweetened beverage (SSB) intakes. We performed multivariable logistic regression to estimate ORs and 95% CIs for the relations between duration of Internet use and dietary risk factors, accounting for complex survey sampling and adjusting for potential confounders. Prolonged leisure-time Internet use (≥241 compared with 1–60 min/d) was associated with higher prevalence of frequent skipping breakfast (OR: 1.39; 95% CI: 1.29, 1.49), low intakes of fruits (OR: 1.27; 95% CI: 1.18, 1.36) and vegetables (OR: 1.43; 95% CI: 1.33, 1.55), and high intakes of instant noodles (OR: 1.87; 95% CI: 1.74, 2.02), fast-food (OR: 1.63; 95% CI: 1.49, 1.78), chips/crackers (OR: 1.37; 95% CI: 1.24, 1.52), and SSBs (OR: 1.63; 95% CI: 1.52, 1.75). Prolonged study-time Internet use (≥121 compared with 1–60 min/d) was inversely associated with prevalence of low fruit (OR: 0.94; 95% CI: 0.88, 1.00) and vegetable (OR: 0.91; 95% CI: 0.85, 0.98) intakes but was positively associated with high intakes of instant noodles (OR: 1.10; 95% CI: 1.03, 1.19) and chips/crackers (OR: 1.13; 95% CI: 1.04, 1.23). The overall associations remained consistent in analyses stratified by sex, grade, region, parental co-residence, perceived household income, perceived stress level, physical activity, and obesity status. Our data suggest that prolonged Internet use, particularly during leisure time, is associated with less healthful dietary behaviors in Korean adolescents. Am J Clin Nutr 2021;114:1791–1801.