Association of the timing of evening eating with BMI z-score and waist-to-height ratio among preschool-aged children in Finland.

Later timing of eating has been associated with higher adiposity among adults and children in several studies, but not all. Moreover, studies in younger children are scarce. Hence, this study investigated the associations of the timing of evening eating with BMI z-score and waist-to-height ratio, and whether these associations were moderated by chronotype among 627 preschoolers (3-6-year-olds) from the cross-sectional DAGIS survey in Finland. Food intake was measured with three-day food records, and sleep was measured with hip-worn actigraphy. Three variables were formed to describe the timing of evening eating: 1) clock time of the last eating occasion, 2) time between the last eating occasion and sleep onset, and 3) percentage of total daily energy intake (%TDEI) consumed two hours before sleep onset or later. Chronotype was assessed as a sleep debt-corrected midpoint of sleep on the weekend (actigraphy data). The data were analysed with adjusted linear mixed effects models. After adjusting for several confounders, the last eating occasion occurring closer to sleep onset (estimate = -0.006, 95% CI = -0.010; -0.001) and higher %TDEI consumed before sleep onset (estimate = 0.0004, 95% CI = 0.00003; 0.0007) were associated with higher waist-to-height ratio. No associations with BMI z-score were found after adjustments. Clock time of the last eating occasion was not significantly associated with the outcomes, and no interactions with chronotype emerged. The results highlight the importance of studying the timing of eating relative to sleep timing instead of only as clock time.