Abstract
Background
Circadian misalignment has been associated with weight gain. While short-term trials suggest meal timing, a circadian synchronizer, can aid weight loss in individuals with obesity, long-term evidence linking meal timing to obesity or overweight remains limited.
Methods
We used data from 87,377 adults (Mean age: 44y; 78% Females) in the French NutriNet-Santé prospective cohort study (2009 - 2023; median follow-up: 6 years, IQR: 2.2-11.5). Participants reported their weight and height every 6 months via validated online questionnaires. We assessed time-dependent meal timing variables - timing of first and last eating occasions, nighttime fasting duration, number of eating occasions, eating jetlag (weekday-weekend regularity), and caloric midpoint - using repeated 24h dietary records. Multivariable proportional hazards Cox models, adjusted for confounders including socioeconomic status, baseline BMI, and total energy intake, were used to estimate risks of overweight (BMI ≥25 kg/m²) and obesity (BMI ≥30 kg/m²).
Results
Later first and last eating occasions were associated with a higher overweight risk (9924 cases/383,811 person-years): HR for 1-hr =1.06 (1.04-1.08) and 1.03 (1.01-1.06), respectively, but not with obesity (4194 cases/549,245 person-years). A later caloric midpoint was associated with a higher risk of overweight and obesity: HR = 1.05 (1.03-1.06) and 1.03 (1.01-1.05), respectively. Participants reporting earlier eating timing on weekends than weekdays exhibited a higher risk of overweight (HR = 1.13 (1.00-1.26)) and obesity (HR = 1.21 (1.03-1.43)) compared to those with more regular schedules. Nighttime fasting and number of eating occasions were not associated with any of the outcomes.
Conclusions
This large-scale prospective study suggests potential long-term adverse effects of later meal timing, energy distribution and irregular eating timing patterns on the risks of both overweight and obesity.
Key messages
• Beyond energy intake, later eating and energy distribution and irregular eating timing patterns are associated with higher overweight and obesity risk in adults over a median follow-up of 6 years.
• More prospective studies are needed to corroborate these findings, and translate them into clinical and public health recommendations.