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Background & Aims: Eating at night has been linked to impaired glucose metabolism and dyslipidaemia that is likely a consequence of an underlying disrupted circadian rhythm in metabolic processes. The aim of this study was to explore the gene expression differences after eating a standard test meal or high protein test meal at night compared with the same meal in the morning., Methods: In a cross over design, 10 healthy adults fasted for >10 h and then completed four acute meal challenges at 8am and 8pm on non-consecutive days separated by a wash out, consuming either a high protein low carbohydrate test meal or an isocaloric standard protein and carbohydrate test meal. Fasting and two-hour postprandial blood samples were collected to measure gene expression. For a subset of five participants RNA sequencing was completed on the Illumina NextSeq500., Results: The time of day a meal is consumed had an effect on which genes were differentially regulated in the acute postprandial period, with only 6.5% of differentially expressed genes the same both morning and night. More genes were involved in lipid metabolic pathways in the morning and immune pathways at night. RTqPCR analysis of target genes suggested that key regulatory genes responsible for nutrient sensing and lipid and glucose metabolism are differentially expressed at night. These may play a role in improved blood glucose control in peripheral tissues that is observed after eating in the morning but to a lesser extent or not at all at night. Modulation of the macronutrient composition of a meal led to changes in expression of genes involved in the circadian clock and metabolism., Conclusions: Investigating the differences in the transcriptomic response to food at night provides a greater understanding of the mechanisms underlying the changing metabolic phenotypes, characterised by circulating metabolic biomarkers, according to the time of day., Competing Interests: Conflicts of interest The authors declare no conflicts of interest., (Copyright © 2021. Published by Elsevier Ltd.)

Background & Aims: Eating at night, compared to day-time, results in a relative hyperglycaemia contributing to an increased risk of Type 2 diabetes for those who habitually eat at night, such as shift workers. Meal choice at night can adversely impact postprandial glycaemia. Meals high in protein have the capacity to favourably reduce night time perturbations in glucose. The aim of this study was to examine if a high protein meal attenuates postprandial glucose at night, compared with a standard protein meal., Methods: In a 2 × 2 factor cross over design, healthy adults completed four acute meal challenges. Test meals were consumed at 8am and 8pm on separate occasions; a high protein (HP) meal (41% of energy from protein, 29% from carbohydrates) or isocaloric standard meal (15% from protein, 46% from carbohydrate). Bloods were sampled at fasting and for three hours postprandially and incremental area under the curve (iAUC) determined using the trapezoid rule. Freidman's test was conducted prior to post hoc Wilcoxon sign test, and significance set at p < 0.0083 after Bonferroni correction., Results: Plasma glucose median (IQR) iAUC after the HP meal was similar to the standard meal when consumed in the morning (12.9 (19.9) vs. 36.4 (99.6)mmol/L.3 h, p = 0.028). The HP meal elicited a significantly lower glucose iAUC (59.6 (117.0)mmol/L.3 h) compared to the standard meal (208.8 (154.1)mmol/L.3 h) when consumed at night (p = 0.005). No significant differences in insulin responses were found between test meals, at either time of day (p = 0.100)., Conclusion: A HP meal is effective in attenuating the postprandial glucose excursion observed with night eating by 71.4%, compared to a meal with a macronutrient composition within dietary guidelines. If eating at night, reducing the carbohydrate content of a meal, and replacing this with protein, can result in a more favourable postprandial metabolic response., Trial Registration: Trial ID number: ACTRN12617000294358, Website of trial registry: http://www.anzctr.org.au/., (Copyright © 2019 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Understanding shift workers dietary intake patterns may inform interventions targeted at lowering chronic disease risk. This study examined the temporal distribution of food intake as shift workers rotate between night shifts, day shift and/or days off to identify differences in energy intake, eating frequency, and adherence to dietary guidelines by shift type (night shift vs. day). Night shift (NS) workers completed a four-day food diary that included a minimum of two night shifts and one-day shift (DS)/day off (DO), recording all food, beverages and time of consumption. Comparisons were between shift types, using ANOVA for continuous data and generalized estimating equations for count data, data reported as mean (SE). When comparing NS and DSDO, there were no differences in energy intake (24 h) (8853 (702) vs. 9041 (605) kJ, n = 22) or adherence to dietary guidelines. There was no difference between the number of eating occasions on NS and DSDO (5.6(0.3) vs 5.1(0.6) occasions) but less energy per eating occasion at night (1661(125) vs 1933(159) kJ). When working NS compared with DSDO there was higher total sugar (%E, 19.1(2.0) vs 15.0(2.4)) and lower saturated fat (%E, 13.8(1.2) vs 15.7(1.3)). Further, DSDO were characterized by a pattern of three main meals and a prolonged fasting period. It is important to determine if reducing eating occasions and providing opportunities for fasting improves metabolic health.

There is evidence to indicate that the central biological clock (i.e., our endogenous circadian system) plays a role in physiological processes in the body that impact energy regulation and metabolism. Cross-sectional data suggest that energy consumption later in the day and during the night is associated with weight gain. These findings have led to speculation that when, as well as what, we eat may be important for maintaining energy balance. Emerging literature suggests that prioritising energy intake to earlier during the day may help with body weight maintenance. Evidence from tightly controlled acute experimental studies indicates a disparity in the body's ability to utilise (expend) energy equally across the day and night. Energy expenditure both at rest (resting metabolic rate) and after eating (thermic effect of food) is typically more efficient earlier during the day. In this review, we discuss the key evidence for a circadian pattern in energy utilisation and balance, which depends on meal timing. Whilst there is limited evidence that simply prioritising energy intake to earlier in the day is an effective strategy for weight loss, we highlight the potential benefits of considering the role of meal timing for improving metabolic health and energy balance. This review demonstrates that to advance our understanding of the contribution of the endogenous circadian system toward energy balance, targeted studies that utilise appropriate methodologies are required that focus on meal timing and frequency., Competing Interests: The authors declare no conflict of interest.

Eating at night time, as is frequent in shift workers, may contribute to increased cardiovascular disease (CVD) risk through a disruption in usual lipid metabolism, resulting in repeated and sustained hyperlipidemia at night. This systematic review aimed to investigate the impact of eating a meal at night compared with the same meal eaten during the day on postprandial lipemia. Six databases were searched: CINAHL Plus, Cochrane Library, EMBASE, Ovid MEDLINE, Informit, and SCOPUS. Eligible studies were original research cross-over design with a minimum fasting period of 5 h before testing preceded by a standardized control meal; measured postprandial triacylglycerol (TAG) for 5 h or greater; had meal time between 0700 h and 1600 h for day time and between 2000 h and 0400 h for night time; and had within-study test meals (food or drink) that were identical in macronutrient composition and energy. Two authors independently completed eligibility and quality assessment using the American Dietetic Association Quality Criteria Checklist for Primary Research. After removing duplicates, 4,423 articles were screened, yielding 5 studies for qualitative synthesis. All studies identified at least one parameter of the postprandial TAG response that was different as a result of meal time (e.g., the total concentration or the time course kinetics). Two studies reported a greater total TAG concentration (area under curve) at night compared with day, and 3 studies found no difference. Four studies reported that the kinetics of the postprandial time course of TAGs was different at night compared with during the day. Inconsistent reporting in the primary studies was a limitation of the review. Night eating may negatively affect postprandial lipemia and this review shows there is a need to rigorously test this using standardized methods and analysis with larger sample sizes. This is critical for informing strategies to lower CVD risk for shift workers.

Introduction: Shift work is an independent risk factor for cardiovascular disease (CVD). Shift workers who are awake overnight and sleep during the day are misaligned with their body's endogenous circadian rhythm. Eating at night contributes to this increased risk of CVD by forcing the body to actively break down and process nutrients at night. This pilot study aims to determine whether altering meal timing overnight, in a shift working population, will impact favourably on modifiable risk factors for CVD (postprandial bplasma lipids and glucose concentration)., Methods and Analysis: A randomised cross-over study with two 4-week test periods, separated by a minimum of a 2-week washout will be undertaken. The effectiveness of redistributing energy intake overnight versus ad libitum eating patterns on CVD risk factors will be examined in night shift workers (n=20), using a standard acute test meal challenge protocol. Primary outcomes (postprandial lipids and glucose) will be compared between the two conditions: post-intervention and post-control period using analysis of variance. Potential effect size estimates to inform sample size calculations for a main trial will also be generated., Ethics and Dissemination: Ethics approval has been granted by the Monash University Human Research Ethics Committee (2017-8619-10329). Outcomes from this study will determine whether eliminating food intake for a defined period at night (1-6 am) impacts favourably on metabolic risk factors for CVD in night shift workers. Collective results from this novel trial will be disseminated through peer-reviewed journals, and national and international presentations. The results are essential to inform health promotion policies and guidelines for shift workers, especially those who aim to improve their metabolic health., Trial Registration Number: ACTRN12617000791336; Pre-results., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Meals consumed out of synchronisation with normal circadian rhythms are associated with metabolic dysregulation. Changes in macronutrient composition of meals can improve metabolic responses during the day. Therefore, we aimed to investigate whether macronutrient manipulation of meals alters postprandial glucose and lipid responses and the expression of circadian genes during the night. In a randomised crossover trial, 16 overweight males with high fasting lipids were fed isocaloric meals (2.7 MJ) at 0000 h. The meals differed primarily in total fat and total sugars content (control (8% total sugar, 5% saturated fat) vs test (16% total sugar, 26% saturated fat)). Postprandial blood samples were collected for glucose, insulin (3 h) and triglycerides (6 h) and analysed as incremental area under the curve (iAUC). RNA was extracted at 0 h, 2 h and 4 h and changes in expressions of the circadian genes clock and Per 1–3 analysed. Postprandial glucose (p = 0.04) and insulin iAUC (p = 0.02) were significantly higher after consumption of the test meal compared to the control meal. Postprandial triglyceride iAUC was not statistically different between the two meal types (p = 0.72). No change in circadian gene expression was observed after the two meals. Our results showed that macronutrient composition affects postprandial metabolic response at night. It emphasizes the need to consider the role and effects of night time eating, when developing metabolic disease prevention strategies for shift workers. ACTRN12618001115224. http://www.anzctr.org.au/. Retrospectively registered after data collection. [ABSTRACT FROM AUTHOR]