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Nightly fasting duration and meal timing are associated with metabolic disorders. This study aimed to investigate the relationships of nightly fasting duration and meal timing with type 2 diabetes mellitus (T2DM) using data from the 2016–2020 Korea National Health and Nutrition Survey. A total of 22,685 adults ≥ 19 years were included in this study. Nightly fasting duration was calculated by subtracting the interval between the day’s first and last meal eating times from 24 h. The meal timing were analyzed using various parameters, including the times of the first and last eating episodes and the percentage of energy intake during the morning (05:00 to 9:00 a.m.), evening (06:00 to 09:00 p.m.), and night (after 09:00 p.m.). Men who fasted nightly for ≥ 12 h had lower odds of T2DM (odds ratio (OR): 0.86; 95% confidence interval (CI): 0.75–0.99) than those who fasted for < 12 h. Individuals who had their last meal after 09:00 p.m. had higher odds of T2DM (OR: 1.19, 95% CI: 1.03–1.38, men; OR: 1.19, 95% CI: 1.01–1.40, women). Additionally, the percentage of energy intake during the evening was associated with increased odds of T2DM (OR: 1.41, 95% CI: 1.08–1.84, men; OR: 1.32, 95% CI: 1.02–1.70, women). These findings emphasize the importance of nightly fasting duration and meal timing in modulating the risk of T2DM among Korean adults.

Nightly fasting duration (NFD) and eating timing and frequency may influence cardiometabolic health via their impact on circadian rhythms, which are entrained by food intake, but observational studies are limited. This 1-year prospective study of 116 US women (33 &plusmn, 12y, 45% Hispanic) investigated associations of habitual NFD and eating timing and frequency with cardiovascular health (CVH, American Heart Association Life&rsquo, s Simple 7 score) and cardiometabolic risk factors. NFD, eating timing and frequency, and nighttime eating levels were evaluated from 1-week electronic food records completed at baseline and 1 y. In multivariable-adjusted linear regression models, longer NFD was associated with poorer CVH (&beta, = &minus, 0.22, p = 0.016 and &beta, 0.22, p = 0.050) and higher diastolic blood pressure (DBP) (&beta, = 1.08, p &lt, 0.01 and &beta, = 1.74, p &lt, 0.01) in cross-sectional and prospective analyses, respectively. Later timing of the first eating occasion at baseline was associated with poorer CVH (&beta, 0.20, p = 0.013) and higher DBP (&beta, = 1.18, p &lt, 0.01) and fasting glucose (&beta, = 1.43, p = 0.045) at 1 y. After adjustment for baseline outcomes, longer NFD and later eating times were also associated with higher waist circumference (&beta, = 0.35, p = 0.021 and &beta, = 0.27, p &lt, 0.01, respectively). Eating frequency was inversely related to DBP in cross-sectional (&beta, 1.94, p = 0.033) and prospective analyses (&beta, 3.37, p &lt, 0.01). In cross-sectional analyses of baseline data and prospective analyses, a higher percentage of daily calories consumed at the largest evening meal was associated with higher DBP (&beta, = 1.69, p = 0.046 and &beta, = 2.32, p = 0.029, respectively). Findings suggest that frequent and earlier eating may lower cardiometabolic risk, while longer NFD may have adverse effects. Results warrant confirmation in larger multi-ethnic cohort studies with longer follow-up periods.

Emerging studies indicate that meal timing is linked to cardiometabolic risks by deterioration of circadian rhythms, however limited evidence is available in humans. This large-scale cross-sectional study explored the associations of meal timing and frequency with obesity and metabolic syndrome among Korean adults. Meal timing was defined as nightly fasting duration and morning, evening, and night eating, and meal frequency was estimated as the number of daily eating episodes using a single-day 24-hour dietary recall method. Meal frequency was inversely associated with prevalence of abdominal obesity, elevated blood pressure, and elevated triglycerides in men only. Independent of the nightly fasting duration and eating episodes, morning eating was associated with a lower prevalence of metabolic syndrome (odds ratio (OR), 0.73, 95% confidence interval (CI), 0.57&ndash, 0.93 for men and OR, 0.69, 95% CI, 0.54&ndash, 0.89 for women) than no morning eating, whereas night eating was associated with a 48% higher prevalence of metabolic syndrome (OR, 1.48, 95% CI, 1.15&ndash, 1.90) than no night eating in men only. Longer fasting duration and less sleep were associated with obesity and metabolic syndrome. These findings suggest that overall eating patterns, including energy distribution across the day, eating frequency, and sleep duration, rather than fasting duration alone, are related to cardiometabolic risks in free-living Korean adults.