Associations between School Lunch and Obesity in Korean Children and Adolescents Based on the Korea National Health and Nutrition Examination Survey 2017–2019 Data: A Cross-Sectional Study

Obesity in children and adolescents is a serious global problem. In Korea, approximately 35% of students’ daily nutrient intake is from school lunch (SL), and all schools provide SL. However, the association between SL and obesity remains controversial. This study examined this association and the daily nutrient intake according to lunch type in Korean children and adolescents. We analyzed 1736 individuals aged 7–18 from the Korea National Health and Nutrition Examination Survey (2017–2019), a cross-sectional study, using logistic regression analysis with odds ratios and 95% confidence intervals. The SL group had higher energy and greater phosphorus, potassium, vitamin A, carotene, vitamin B1, and niacin intake than the non-school lunch (NSL) and skipping lunch (SKL) groups. Protein intake was also higher in the SL group than in the NSL group. The SKL group had higher saturated fatty acid intake, and was thereby 2.5, 1.9, and 2.5 times more likely to have obesity, overweight and obesity, and central obesity (p = 0.0071, 0.0459, 0.0092), respectively, than the SL group. Therefore, the SL group consumed more appropriate nutrients than the NSL and SKL groups, and was less likely to become obese than the SKL group. More in-depth prospective studies are needed to elucidate the causal relationship between SL and obesity.