Associations Between Fasting Duration and Nutrition Quotient Scores in Korean Adults.

OBJECTIVE: To examine the association between fasting duration and dietary quality (Nutrition Quotient [NQ]) in a real-world community setting. DESIGN: Cross-sectional. SETTING: Community-based adults recruited via online announcements. PARTICIPANTS: Adults aged 19-64 years (n = 320) were classified by habitual fasting duration: < 14 hours (n = 106) and ≥ 14 hours (n = 214). Individuals with shift work-related irregular sleep-wake or meal schedules were excluded. VARIABLES MEASURED: Online questionnaires assessed general characteristics, sleep and smartphone use, and 18 NQ items (Balance, Moderation, and Practice). Fasting duration was calculated from self-reported times of the first and last meals. Body mass index (BMI) was computed from self-reported height and weight. ANALYSIS: Group differences were examined using χ² and t tests. Analysis of covariance was used to compare total NQ and factor scores between groups, adjusting for sex, age, sleep duration, and smartphone use. RESULTS: The < 14-hour group showed significantly higher total NQ (P < 0.001) and factor scores, including Balance (P < 0.001), Moderation (P = 0.008), and Practice (P = 0.01). Longer fasting was associated with a lower intake of key food groups and markedly reduced breakfast consumption, whereas BMI did not differ. CONCLUSIONS AND IMPLICATIONS: In real-life fasting practices, prolonged fasting is associated with poorer dietary quality rather than healthier eating. These findings support emphasizing meal timing, breakfast consumption, and dietary diversity rather than fasting duration alone in nutrition education.