1, 2) Percentage of mothers or fathers whose education levels were equal to or lower than high school graduate at the time of survey participation, 3) Subjective ratings for his or her household income condition. 1: very poor, 5: very abundant, 4) Subjects fell into a category using his or her body mass index score based on the BMI-for-age values of 2007 Korea Growth Charts released by Korea Centers for Disease Control and Prevention. Underweight, healthy weight, overweight, and obesity designated BMI ranges of less than the 5th percentile, 5th percentile to less than the 85th percentile, 85th to less than the 95th percentile, and equal to or greater than the 95th percentile, respectively, 5) ME: male elementary schoolers, FE: female elementary schoolers, MM: male middle schoolers, FM: female middle schoolers, 6) a, b: values not sharing common superscript letters within the same row are significantly different at p < 0.05 by Tukey's multiple range test

1) Subjects were asked to answer about the consumption frequencies for 10 food items during past one week. Frequencies were assessed by 7 categories (1: none, 2: 1-2/week, 3: 3-4/week, 4: 5-6/week, 5: 1/day, 6: 2/day, 7: 3 or more/day) and then reconstructed to three categories by combining categories, 2) ME: male elementary schoolers, FE: female elementary schoolers, MM: male middle schoolers, FM: female middle schoolers, 3) Chi-square test

Items with superscripts were presented with a few examples on the questionnaire, 1) pizza, hamburger, and fried chicken 2) Processed and frozen foods, 3) hams, bacons and sausages, 4, 5) HF and UHF are unstandardized abbreviations for healthful foods and unhealthful foods, respectively

1-4) 1: 0/week, 2: 1-2/w, 3: 3-4/w, 4: 5-6/w, 5: 1/day, 5) HF indicates the factor variable consisting of consumption frequencies of kimchi, vegetable side dishes, fruits, milk, and fish. UHF included the food items of fast foods, ramyun, carbonated soft drinks, frozen foods, and processed red meats 1: 0/w, 2: 1-2/w, 3: 3-4/w, 4: 5-6/w, 5: 1/d, 6: 2/d, 7: 3 or more/d, 6) Money spent in won, 7) ANOVA followed by Scheffe's test at α = 0.05 level, 8) ME: male elementary schoolers, FE: female elementary schoolers, MM: male middle schoolers, FM: female middle schoolers

1-3) WD and WE designated average amounts of each food group consumed at weekday and weekend, respectively. DIF was calculated by subtracting weekend value from weekday value. Paired t-test was performed for the difference between weekday and weekend values, 4) ME: male elementary schoolers, FE: female elementary schoolers, MM: male middle schoolers, FM: female middle schoolers 5-8) ^*: p < 0.05, ^**: p < 0.01, ^***: p < 0.001, ^****: p < 0.0001

1-3) WD and WE designated the average amounts of energy and nutrient consumed at weekday and weekend, respectively. DIF was calculated by subtracting weekend value from weekday value, 4) Mean value, 5) ME: male elementary schoolers, FE: female elementary schoolers, MM: male middle schoolers, FM: female middle schoolers, 6-9) ^*: p < 0.05, ^**: p < 0.01, ^***: p < 0.001, ^****: p < 0.0001

1) Energy intake was compared with the age- and sex-specific estimated energy requirement, dietary fiber and sodium were the percentage of adequate intake values, and the others were calculated as the percentage of recommended intake values of 2005 KDRIs, 2) Mean ± SD, 3) ANOVA followed by Scheffe's test at α = 0.05 level ME: male elementary schoolers, FE: female elementary schoolers, MM: male middle schoolers, FM: female middle schoolers