Associations of meal timing and sleep duration with incidence of obesity: a prospective cohort study

Objectives: Late mealtime and short sleep are known to be associated with obesity risk due to a misaligned circadian rhythm. This study aimed to investigate the relationship between obesity and mealtime and sleep duration using the Korean Genome and Epidemiology Study (KoGES) data. Design: Longitudinally prospective cohort study. Setting: Population-based. Participants: KoGES analysed data from 9,474 Korean adults with an average age of 54- years old at baseline. Measurements: Meal timing was defined as the eating occasions of the day reported by the participant eating a 24-h dietary recall method. Sleep duration was categorized as <6, 6–7, 7–8, and ≥8 h. The Cox proportional hazard model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for incident obesity according to meal timing, sleep duration, and nightly fasting duration. Results: During a mean follow-up of 3.5 years, 826 participants developed obesity. In the multivariable-adjusted analysis, midnight snack eating (HR, 1.20; 95% CI, 1.02–1.41) and higher energy intake from midnight snacks (HR, 1.26; 95% CI, 1.06–1.49) were associated with a higher risk of obesity. Sleeping 8 h or more (HR, 0.67; 95% CI, 0.53–0.85) was associated with a lower risk of obesity. Conclusions: Our findings highlight the importance of meal and sleep times and suggest that healthy eating habits related to the time of day.