Identification of Chrononutrition Factors Associated With Chronic Non-communicable Diseases and Investigation of Circadian Gene-Chrononutrition Interactions in the Development of Chronic Non-communicable Diseases Among Koreans

Many nutritional epidemiological studies conducted among various population groups (Cohort study, RCT study) found that chrono-nutrition factors such as morning fasting, functional supplements like fish oils, intermittent fasting, and time-restricted feeding were related to weight management, cardiovascular metabolism, blood glucose, and blood lipid metabolism. Some dietary intervention studies have found its effect on weight loss, sleep improvement, blood glucose improvement, insulin sensitivity, β cell reactivity, blood pressure, oxidative stress, and appetite improvement. This intervention study aims to investigate changes in chronic disease risk factors according to the daily meal exposure time (from the first meal to the last meal or snack) in healthy adult women.

The subjects of this study are healthy adult women aged the 30s - 40s with a body mass index (BMI) of 23 kg/m2 or a body fat rate of 28% or higher and would be excluded if the participants have inconsistent eating patterns or weight changes of 5% or more over the past three months, are pregnant or breastfeeding, are heavy drinkers (alcohol intake of 10 g/day, 300 cc), and are smokers.

A total of 10 weeks of intervention are conducted. Two meal exposure time groups are performed for four weeks each, and there is a two-week wash-out between different exposure times. The total meal period per day would be limited to 8 hours ± 30 minutes for the TRF group, and 14 hours ± 30 minutes for the EXF group. Each group will be divided into early type (before 10 a.m.) and late type (after 10 a.m.) depending on the participants' first meal timing and will be changed to another group in the second intervention period. During the 10-week study, blood (to collect genetic information related to blood lipids, blood sugar, 10ml) and urine (to collect metabolic indicators such as urine sodium, 15ml) samples would be collected four times.

Changes in evaluation variables (body composition indicators, urine indicators, or blood indicators) before and after each intervention period will be tested using the paired t-test. The association between meal time and changes in biomarkers will be tested by ANOVA using a mixed model. The analysis would be adjusted for covariates related to lifestyle (sleeping time, physical activity level, smoking status) and chrono-nutrition-related genetic information.