The timing of macronutrient and major food group intake and associations with mortality among US adults, 1999-March 2020: a serial cross-sectional study.

Abstract

Background: Eating timing has been increasingly linked to health, yet national trends in macronutrient/food group timing and their health implications remain unclear.

Objective: To characterize trends in timing of energy, macronutrient, and food group intake among US adults and examine their associations with mortality.

Methods: In this serial cross-sectional study of adults aged ≥20 years with ≥1 valid 24-hour dietary recall (National Health and Nutrition Examination Survey, 1999-March 2020), we examined secular trends in timing of energy, macronutrients, and major food group intake. Associations with mortality (through December 2019) were examined using Cox models.

Results: Among 50,264 adults, evening (6-10pm) accounted for the highest daily energy intake (weighted mean proportions across years, 31.9%-33.3%), followed by noon (10am-2pm, 24.7%-26.8%), afternoon (2-6pm, 19.9%-21.8%), morning (6-10am, 13.5%-14.9%), and overnight (10pm-6am, 5.6%-6.5%); midnight (10-2am) eating occurred in 23.4%-28.0% of the population. Macronutrient and food groups followed similar patterns, except whole grain (peaked in the morning) and fruit, egg, and dairy intake (more evenly distributed). Over years, noon and midnight energy intake proportions declined, while afternoon proportion increased; secular trends varied by macronutrients/food groups. Fasting started at 8:34-8:51pm and ended at 8:41-8:52am; intake midpoint was 2:38-2:48pm; intake duration was 11.9-12.2 hours. Male, non-Hispanic black, and socioeconomically disadvantaged groups had greater midnight intake proportions and later intake midpoints. Reallocating 5% of daily energy to midnight was associated with higher cardiovascular mortality (HR, 1.09; 95% CI, 1.02,1.17), driven by carbohydrates; reallocating 5% to predawn (2-6am) was associated with higher cancer mortality (1.22;1.05,1.41), driven by proteins. Each 1-hour delay in fasting and intake midpoint was associated with an 8%-9% higher cardiovascular mortality.

Conclusion: Overnight intake and delayed eating timing are prevalent among US adults, especially among socioeconomically disadvantaged groups, and were associated with higher mortality, particularly for specific macronutrients/foods, supporting eating timing recommendations integrating food composition.