Night-time eating and body weight status among US adults, 2007-2016

Differences in nutritional profile by chronotype among 12-h day shift and night shift nurses

Acute care nurses may suffer substantial fatigue if working night shift or if assigned a shift contrasting their preferred sleep-wake patterns, called chronotype. Nurses are at higher risk for diet-related, metabolic diseases compared to other healthcare professionals. Yet, the impact of preferred chronotype and mismatch to assigned shift on nutritional intake and risk for metabolic disease among acute care nurses is unclear. This observational study analyzed dietary data from 52 acute care nurses. Participants completed the revised morningness-eveningness questionnaire which gives a total score between 4 and 26. Lower scores (<12) were flagged as evening type (E-type), higher scores (>17) defined as morning type (M-type), and scores between 12 and 17 were categorized as neither types (N-type). N-type participants were considered chronotype matched when assigned to either shift, whereas E-types were only considered matched if assigned to night shift, and M-types matched only if assigned to day shift. Participants also recorded all dietary intake for 7 d (reflecting a typical workweek) in the MyFitnessPal phone application. Findings indicated that eveningness nurses had markers of MetS, including a significantly larger body mass index and waist circumference than N-types (p < 0.05). E-types also consumed, on average, more calories than other chronotypes (m = 1833.7 kcal), although this was not a statistically significant finding. Mismatched day (n = 7, 13.4%) and night (n = 5, 9.6%) nurses in our sample consumed, on average, more calories (m = 1935.1 kcal, m = 1981.2 kcal, respectively) than matched day (n = 24, 46.2%, m = 1642.6 kcal) or night (n = 16, 30.8%, m = 1599.1 kcal) nurses, although this finding was not statistically significant. Mismatched day nurses consumed significantly less fiber than day matched nurses (median = 10.9 g versus median = 18.5 g, p = 0.04), while night mismatched consumed significantly more fiber compared to night matched (median = 21 g versus median = 12.2 g, p = 0.05) nurses. Participant diets overall did not follow recommendations by the United States Department of Agriculture (USDA), who consumed a higher percentage of calories from saturated fats and a smaller percentage of calories from fiber, habits which increase risk for metabolic syndrome. Further research surrounding nutritional pathways utilizing larger samples is needed to uncover relationships with metabolic syndrome especially for eveningness-type nurses or if working a shift mismatched with preferred chronotype.

The impact of a self-selected time restricted eating intervention on eating patterns, sleep, and late-night eating in individuals with obesity

Background

Time restricted eating (TRE), limiting eating to a specific daily window, is a novel dietary intervention, but the mechanisms by which TRE results in weight loss remain unclear. The goal of the current study was to examine changes in eating patterns, sleep, and late-night eating, and associations with health outcomes in a secondary analysis of a 12-week self-selected TRE intervention.

Methods

Twenty participants 18-65 years with BMI ≥25 kg/m2 completed the 12-week trial. Participants randomized to TRE (n = 11) were instructed to eat during a self-selected 8-h window, while the non-TRE group (n = 9) followed their typical eating habits. All participants logged oral intake using the myCircadian Clock mobile application throughout the entire intervention. Anthropometrics, HbA1c, an oral glucose tolerance test, and 2 weeks of actigraphy monitoring were completed at pre-intervention and end-intervention. Independent samples t-tests compared differences between groups. Data are presented as mean ± standard deviation.

Results

At preintervention, late night eating was significantly associated with higher fasting glucose (r = 0.59, p = 0.006) and higher HbA1c (r = 0.46, p = 0.016). The TRE group significantly delayed the timing of the first eating occasion by 2.72 ± 1.48 h relative to wake time (p < 0.001) and advanced the timing of the last eating occasion by 1.25 ± 0.8 h relative to bedtime (p < 0.001). The non-TRE group, on average, maintained their eating pattern. Sleep measures did not change from pre- to end-intervention, however greater restriction of the eating window was associated with longer sleep duration at end-intervention (β = -0.46 [95% CI -9.2, -0.4], p = 0.03). The TRE group significantly reduced the prevalence of late night eating (eating within 2 h of bedtime) by 14 ± 6% (p = 0.028) with 63% of participants completely eliminating late night eating at end-intervention.

Conclusion

A self-selected TRE intervention significantly shifted meal timing, reduced late-night eating while prolonging sleep duration.

Trial registry

ClinicalTrials.gov, identifier: 03129581.