Day-to-Day Variability in Meal Timing and Its Association with Body Mass Index: A Study Using Data from a Japanese...

Area of Science:

• Chrononutrition
• Circadian biology
• Metabolic health

Background:

• Weekday-weekend mealtime differences ('eating jetlag') correlate with higher body mass index (BMI).
• Modern work patterns introduce day-to-day mealtime variability, potentially misaligning eating with circadian rhythms.
• Investigating mealtime variability beyond simple weekday-weekend shifts is crucial for understanding metabolic health.

Purpose of the Study:

• To quantitatively assess and visualize daily mealtime variability over one month using food log data.
• To investigate the association between breakfast time irregularity and body mass index (BMI).
• To explore age and sex differences in chrono-nutritional factors related to BMI.

Main Methods:

• Retrospective, cross-sectional analysis of food log data (n=1072) from a Japanese mobile application.
• Quantification of mealtime irregularity using composite phase deviation (CPD).
• Stratification of data by sex and age tertile for detailed analysis.

Main Results:

• Approximately 18% of participants exhibited irregular breakfast timing (CPD > 1 hour).
• Evening chronotype was associated with BMI in younger women.
• Breakfast time irregularity was significantly associated with BMI in older women.

Conclusions:

• Daily mealtime variability is an independent chrono-nutritional factor associated with BMI.
• The specific chrono-nutritional factors influencing BMI may vary across different age groups.
• Understanding meal timing regularity is important for metabolic health interventions.