Chronotype, temporal patterns of eating and diet composition on work and work-free days

Temporal patterns of eating and diet composition are influenced by factors including circadian preference (chronotype) and work schedule, yet their combined influence is unknown. We investigated relationships between chronotype, temporal eating patterns (duration of eating window (DEW), time of first (FEO) and last (LEO) eating occasions), and diet composition on workdays (WD) and work-free days (FD). Non-shift workers (n = 39) completed the Chrononutrition Questionnaire (CNQ) (age: 38.8 ± 17.2 years, BMI: 24.8 ± 4.78 kg/m², 82% female) that captures chronotype and temporal eating patterns, and returned work diaries (work schedule) and 7-day food diaries (diet composition) after 2 weeks. Twenty-nine participants provided dietary data for at least two work and work-free days. Later chronotype was associated with later FEO on FD (r_s = 0.45, p = 0.004), later LEO on FD (r_s = 0.60, p < 0.001) and WD (r_s = 0.61, p < 0.001), and longer DEW on WD (r_s = 0.37, p = 0.024). Relationships between chronotype and diet composition were small. Later FEO was associated with higher % energy from fat (r_s = 0.39, p = 0.043) and lower fibre intake (r_s = -0.69, p < 0.001) on WD. Later chronotypes had shorter and later eating windows on FD than WD. Our findings suggest that relationships between chronotype, temporal eating patterns, and diet composition differ by day type. Further investigation may inform dietary strategies that are day-specific.