Timing of Food Intake: Identifying Contributing Factors to Design Effective Interventions

Advancing Chrononutrition for Cardiometabolic Health: A 2023 National Heart, Lung, and Blood Institute Workshop Report

The circadian system maintains optimal biological functions at the appropriate time of day, and the disruption of this organization can contribute to the pathogenesis of cardiometabolic disorders. The timing of eating is a prominent external time cue that influences the circadian system. "Chrononutrition" is an emerging dimension of nutrition and active area of research that examines how timing-related aspects of eating and nutrition impact circadian rhythms, biological processes, and disease pathogenesis. There is evidence to support chrononutrition as a form of chronotherapy, such that optimizing the timing of eating may serve as an actionable strategy to improve cardiometabolic health. This report summarizes key information from the National Heart, Lung, and Blood Institute's virtual workshop entitled "Chrononutrition: Elucidating the Role of Circadian Biology and Meal Timing in Cardiometabolic Health," which convened on May 2 to 3, 2023, to review current literature and identify critical knowledge gaps and research opportunities. The speakers presented evidence highlighting the impact on cardiometabolic health of earlier and shorter eating windows and more consistent day-to-day eating patterns. The multidimensionality of chrononutrition was a common theme, as it encompasses multiple facets of eating along with the timing of other behaviors including sleep and physical activity. Advancing the emerging field of chrononutrition will require: (1) standardization of terminology and metrics; (2) scalable and precise tools for real-world settings; (3) consideration of individual differences that may act as effect modifiers; and (4) deeper understanding of social, behavioral, and cultural influences. Ultimately, there is great potential for circadian-based dietary interventions to improve cardiometabolic health.

Later eating timing in relation to an individual internal clock is associated with lower insulin sensitivity and affected by genetic factors

BACKGROUND

Although the contribution of the circadian clock to metabolic regulation is widely recognized, the role of eating timing in glucose metabolism and diabetes risk remains insufficiently studied. This study aimed (i) to investigate the link between the eating timing pattern relative to individual clock and glucose homoeostasis and (ii) to explore the contribution of genetic and environmental factors to eating timing parameters.

METHODS

In 92 adult twins (NCT01631123), glycaemic traits were assessed using the oral glucose tolerance test. Parameters of eating timing pattern (eating timing itself, daily calorie distribution, and eating frequency) were extracted from five-day food records. Caloric midpoint defined as the time point at which 50% of daily calories are consumed. Circadian timing of eating was determined as a time interval between the clock time of eating and a corrected midpoint of sleep, a chronotype marker. Heritability of eating timing components was estimated by comparing correlations within monozygotic and dizygotic twin pairs and fitting genetic structural equation models.

FINDINGS

Among components of eating timing, the most associations were found for the circadian time of caloric midpoint (CCM). Later CCM was significantly associated with poorer insulin sensitivity, i.e. with lower ISI Stumvoll (β = 0.304, p = 5.9 × 10-4) and higher HOMA-IR (β = -0.258, p = 0.011) indices, as well as with higher fasting insulin levels (β = -0.259, p = 0.013), even after the model adjustment for sex, age, daily energy intake, and sleep duration. Later CCM also demonstrated robust associations with higher BMI and waist circumference. All eating timing components showed high or moderate heritability and were strongly related to individual sleep timing.

INTERPRETATION

Later eating timing in relation to an individual internal clock is associated with lower insulin sensitivity. Shifting the main calorie intake to earlier circadian times may improve glucose metabolism, but genetic factors could influence the feasibility and effectiveness of eating-timing based interventions. The findings should be investigated in a larger cohort.

FUNDING

This work was supported by the German Research Foundation (DFG RA 3340/4-1 to OP-R, project number 530918029), by the European Association for the Study of Diabetes (Morgagni Prize 2020 to OP-R), and by the German Federal Ministry of Education and Research (BMBF NUGAT 0315424 to AFHP). The DZD is funded by the German Federal Ministry for Education and Research (01GI0925).

Chrononutrition behaviors in relation to diet quality and obesity: do dietary assessment methods and energy intake misreporting matter?

BACKGROUND

Inconsistent epidemiologic findings on the associations of chrononutrition behaviors with diet quality and adiposity measures may be due to the use of different dietary assessment methodologies and a lack of consideration of dietary misreporting. We aimed to investigate the associations by using questionnaires and diaries, with adjustment for energy intake (EI) misreporting.

METHODS

This cross-sectional study included 1047 Japanese adults aged 20-69 years. We used the Chrono-Nutrition Behavior Questionnaire (CNBQ) or 11-day diaries to assess chrononutrition behaviors (meal frequency, snack frequency, total eating frequency, timing of first eating occasion, timing of last eating occasion, duration of eating window, and eating midpoint) for workdays and non-workdays separately. Eating jetlag was defined as the eating midpoint difference between workdays and non-workdays. Diet quality was assessed using the Healthy Eating Index-2020, based on the Meal-based Diet History Questionnaire (MDHQ) or 4-day weighed food diaries. EI misreporting was evaluated using the Goldberg cut-off principle.

RESULTS

Using questionnaire data (CNBQ and MDHQ), we found inverse associations of snack and total eating frequencies, timing of last eating occasion, eating midpoint, and eating jetlag with diet quality (P < 0.05), irrespective of adjustment for EI misreporting. Also, we found positive associations of meal, snack, and total eating frequencies and duration of eating window with the prevalence of general obesity (body mass index ≥ 25 kg/m2), abdominal obesity (waist circumference ≥ 90 cm for males; ≥ 80 cm for females), or both; many of these associations were only evident (P < 0.05) after adjustment for EI misreporting. In contrast, using diary data, we found no associations between chrononutrition behaviors and diet quality, general obesity, or abdominal obesity, regardless of adjustment for EI misreporting (except for inverse associations of timings of first and last eating occasions and eating midpoint on workdays with diet quality).

CONCLUSIONS

The associations of chrononutrition behaviors with diet quality and obesity were dependent on the methodology used to assess these behaviors. Adjustment for EI misreporting radically changed only the associations with obesity in the questionnaire-based analysis. These findings suggest the importance of careful consideration of dietary assessment method selection and EI misreporting in chrononutrition research.

The effects of chrononutrition, chronotype and sleep behavior variabilities on adiposity traits and appetite sensations among students and staff of a Malaysian university

We investigated the association of chrononutrition, sleep behavior, and chronotype with adiposity and appetite sensations among 220 Malaysian adults (M/F = 57/163; aged 22.02   ±   5.19). Meal times, dietary intake, and appetite sensations (before and after meals) were recorded for two weekdays and one weekend. Sleep behavior was tracked objectively via activity wristband, chronotype was assessed by the Morningness-Eveningness Questionnaire, and anthropometrics/body compositions were measured. Overall participants had significantly later breakfast, lunch, eating midpoint, wake up time, sleep duration, compared to weekdays. Those who belonged to the delay eating jetlag group had significantly higher weekday, but lower weekend eating windows. Larger caloric intake later in the day was significantly associated with lower body mass and adiposity. Delay lunch jetlag class was significantly associated with higher waist-hip ratio. Delayed morning and afternoon chrononutrition behaviors were associated with higher hunger and eating thoughts, and lower fullness sensations pre- and post-meals. Morningness was associated with lower satisfaction and fullness sensations post-breakfast, but higher same sensations pre-dinner. In conclusion, larger caloric intake later in the day and advanced lunch jetlag led to lower adiposity, while delayed chrononutrition behaviours were associated with higher pre- and post-meal appetite sensations.

Relative validity of the Chrono-Nutrition Behavior Questionnaire (CNBQ) against 11-day event-based ecological momentary assessment diaries of eating

BACKGROUND

A growing number of studies have investigated chrononutrition-related variables in relation to health outcomes. However, only a few questionnaires specifically designed for assessing chrononutrition-related parameters have been validated. We aimed to examine the relative validity of the Chrono-Nutrition Behavior Questionnaire (CNBQ) against 11-day event-based ecological momentary assessment (EMA) diaries of eating.

METHODS

Informed by previous research, we developed the CNBQ for the comprehensive assessment of chrononutrition-related parameters, including sleep variables, eating frequency, timing of eating, duration of eating occasions, duration of eating windows, and time interval between sleep and eating, for workdays and non-workdays separately. Between February and April 2023, a total of 1050 Japanese adults aged 20-69 years completed the online CNBQ and subsequently kept event-based EMA food diaries for 11 days, including 6.5 workdays and 4.5 non-workdays on average.

RESULTS

Mean differences between estimates derived from the CNBQ and the EMA food diaries were < 10% for most of the variables examined, both for workdays (27 of 33; 82%) and non-workdays (25 of 33; 76%), and for variables based on differences between workdays and non-workdays, such as eating jetlag (5 of 6; 83%). Spearman correlation coefficients between estimates based on the CNBQ and estimates based on the EMA food diaries were ≥ 0.50 for 26 variables (79%) on workdays and 22 variables (67%) on non-workdays (e.g., mid-sleep time; total eating frequency; timing of first eating occasion, last eating occasion, first meal, and last meal; duration of first meal and last meal; duration of eating window; eating midpoint; and time interval between wake time and first eating occasion and between last meal and sleep time), and 2 variables based on differences between workdays and non-workdays (e.g., eating jetlag base on breakfast timing). Bland-Altman analysis showed that the limits of agreement were wide and that the bias of overestimation by the CNBQ was proportional as mean estimates of the CNBQ and EMA food diaries increased.

CONCLUSIONS

These findings suggest that the relative validity of the CNBQ justifies its use in estimating mean values and ranking individuals for the majority of chrononutrition-related parameters.

The association of famine exposure with healthy lifestyles at different life stages in rural older adults in China

Objective

To assess the potential association between exposure to Chinese famine and healthy lifestyles, as well as any gender disparities in this relationship to provide a scientific basis for the development of effective public health policies and interventions.

Methods

We used binary logistic regression models to estimate the potential association between famine exposure and healthy lifestyles and stratified by sex for comparisons. Unordered multicategory logistic regression model was used to assess the association between famine exposure and healthy lifestyle scores. We presented this association with Odds ratios (OR) with 95% confidence intervals (CI).

Results

A total of 6,458 individuals were enrolled in the current study, of whom 4,155(64.3%) were women. Men exposed to famine in infancy (OR = 0.650, 95%CI: 0.506-0.834) and preschool (OR = 0.788, 95%CI: 0.631-0.985) was negatively associated with non-smoking and women exposed famine in infancy (OR = 0.699, 95%CI: 0.574-0.851), preschool (OR = 0.734, 95%CI: 0.613-0.880), and school age (OR = 0.764, 95%CI: 0.673-0.916) was negatively associated with normal weight, and women were more likely to be central obesity during exposed to famine in infancy (OR = 0.763, 95%CI: 0.624-0.934). The likelihood of having a healthy lifestyle score of 5-6 as an adult was higher for experiencing famine in preschool and school age.

Conclusions

Men exposed to the Chinese famine during infancy were positively associated with smoking and drinking, while women exhibited a positive association with central obesity. Women had unhealthy weight if they experienced famine early in life and a call for attention to nutritional status and women's health in the early life.

Self-Reported Weekend Temporal Eating Patterns of American Adults Differ From Weekday: National Health and Nutrition Examination Surveys: 2015-2020 Prepandemic

BACKGROUND

Weekend-weekday differences in time of ingestive events may be implicated in adverse metabolic and health outcomes. However, little is known about the nature of weekend-weekday differences in temporal eating behaviors of the US adult population.

OBJECTIVE

The study aimed to examine weekend-weekday differences in temporal and energy characteristics of ingestive events self-reported by American adults.

DESIGN

Observational; within-person comparative.

PARTICIPANTS/SETTING

The data were from the National Health and Nutrition Examination Surveys (NHANES) 2015-March 2020 (pre-pandemic) for ≥20-year-old adults who provided 1 weekday (M-Th) and 1 weekend (F, S, Su) 24-h dietary recall (n = 3564 men and 3823 women).

MAIN OUTCOME MEASURES

Prespecified primary temporal outcomes were recalled: time of ingestive events, and the duration of ingestive and fasting windows. Secondary outcomes included frequency and energy characteristics of ingestive events.

STATISTICAL ANALYSIS PERFORMED

Gender-specific, survey-weighted, multiple linear regression models that accounted for complex survey design with dummy covariates for weekend/weekday, mode of recall administration (in-person on day 1 and telephone on day 2), and a respondent-specific fixed intercept.

RESULTS

In both men and women, the weekend recalled time of first ingestive event, breakfast, and lunch were later than weekday (P ≤ .0008); however, no statistically significant differences were observed in time of dinner and the last eating episode. The mean weekend ingestive window (interval between the time of first and last eating events of the day) was shorter by 24 minutes (95% confidence interval [CI], -32, -11) in men and 18 minutes (95% CI, -20, -15) in women, and the mean overnight fasting window was correspondingly longer (P ≤ .0001). No statistically significant differences were observed between weekend and weekday frequency of ingestive events. Energy density of weekend food selections reported by women, and of beverages by men, was found to be higher than weekday (P ≤ .002).

CONCLUSIONS

Weekend ingestive patterns were characterized by later time of first ingestive event, breakfast, and lunch, and selection of higher-energy-density foods and beverages.

Chrononutrition in Chronic Kidney Disease

Chrononutrition, the study of the interaction between biological rhythms and nutrition, has emerged as a promising field for addressing metabolic health. However, its role in chronic kidney disease (CKD) remains underexplored. CKD patients often experience circadian disruptions due to renal, metabolic, treatment-related, and lifestyle factors, which may influence their nutritional status and clinical outcomes. Objective: to synthesize and analyze the existing evidence on chrononutrition in CKD patients, identify knowledge gaps, and propose directions for future research across different stages of CKD. Initially, this review contextualizes circadian physiology, alignment, and chronodisruption to explore such factors in CKD patients, focusing on chrononutrition variables already studied in the general population. We discuss how dietary timing and habit adjustments could influence CKD clinical outcomes, offering insights into circadian impacts on disease management. This new approach could optimize patient care, encouraging further research, particularly in the development of personalized strategies for different stages of the disease.

Weekday-Weekend Differences in Chrononutritional Variables Depend on Urban or Rural Living

BACKGROUND/OBJECTIVES

Studies have highlighted the impact of work and school schedules on food preferences, suggesting that individuals' dietary choices may change during the week to align with their daily routines. Despite the variation in food composition in the population, there is no evidence identifying differences in food intake times and composition across the days of the week in urban/rural locations. Thus, the study's aim was to identify weekday vs. weekend differences in food intake times and composition (calories) between urban and rural areas.

METHODS

Data from 5770 participants (aged 18-59 years) were analyzed from the National Household Budget Survey (POF-IBGE) consisting of two distinct food diary records (weekday + weekend) per individual, including area (urban or rural) information in Brazil.

RESULTS

During weekdays, the time of the first food intake was significantly earlier, and the last food intake time was significantly later compared to weekends, resulting in a longer eating window on weekdays in both urban and rural areas. People living in urban areas exhibited delayed first and last food intake times, resulting in later caloric and eating midpoints compared to people living in rural areas. Periodogram analysis detected weekly rhythmicity (7 days) at the time of the first food intake and the length of the eating window in urban residents.

CONCLUSIONS

The observed 7-day rhythmic pattern of food intake in urban areas, driven by work and school schedules, underscores the influence of urbanization on dietary timing and composition. In contrast, rural areas exhibited more stable and earlier eating patterns. These results emphasize the need for public health interventions to address meal timing and circadian alignment, particularly in urban settings, to mitigate the risk of metabolic disorders and improve overall health outcomes.

Sex-specific association between later circadian timing of food intake and adiposity among Chinese young adults living in real-world settings

Timing of food intake is an emerging aspect of nutrition; however, there is a lack of research accurately assessing food timing in the context of the circadian system. The study aimed to investigate the relation between food timing relative to clock time and endogenous circadian timing with adiposity and further explore sex differences in these associations among 151 young adults aged 18-25 years. Participants wore wrist actigraphy and documented sleep and food schedules in real time for 7 consecutive days. Circadian timing was determined by dim-light melatonin onset (DLMO). The duration between last eating occasion and DLMO (last EO-DLMO) was used to calculate the circadian timing of food intake. Adiposity was assessed using bioelectrical impedance analysis. Of the 151 participants, 133 were included in the statistical analysis finally. The results demonstrated that associations of adiposity with food timing relative to circadian timing rather than clock time among young adults living in real-world settings. Sex-stratified analyses revealed that associations between last EO-DLMO and adiposity were significant in females but not males. For females, each hour increase in last EO-DLMO was associated with higher BMI by 0·51 kg/m2 (P = 0·01), higher percent body fat by 1·05 % (P = 0·007), higher fat mass by 0·99 kg (P = 0·01) and higher visceral fat area by 4·75 cm2 (P = 0·02), whereas non-significant associations were present among males. The findings highlight the importance of considering the timing of food intake relative to endogenous circadian timing instead of only as clock time.

Temporal patterns of energy intake and physical activity and cross-sectional associations with body weight status in children and adolescents: results from the Portuguese National Food, Nutrition and Physical Activity Survey 2015-2016

Temporal energy intake (EI) and physical activity (PA) patterns may be associated with obesity. We aimed to derive and characterise temporal EI and PA patterns, and assess their cross-sectional association with weight status, in 6-to-14-year-old Portuguese participants of the National Food, Nutrition and Physical Activity Survey 2015-2016. We extracted times and EI of all eating occasions from two 1-d food diaries/24-h recalls, while types and times of PA from 4-d PA diaries. We derived EI patterns (n 714) and PA patterns (n 595), using, respectively, a hierarchical and K-means cluster analysis, considering the average proportion of total daily EI (%TEI) and PA intensity (%TPA), within each 2-h interval across the 24-h day. Patterns were labelled based on the 2-h intervals of %TEI/TPA peaks. We assessed the association between patterns and overweight or obesity (BMI z-score ≥ +1 sd) using adjusted logistic regressions (OR (95 % CI)). Three EI patterns emerged: 1 - 'Early afternoon and early evening'; 2 - 'Early afternoon and late evening'; and 3 - 'Late morning, early and mid-afternoon and late evening'. EI Pattern 3 v. Pattern 1 was negatively associated with overweight or obesity (0·49 (0·26, 0·92)). PA Pattern 1 - 'Late morning, mid-afternoon and early evening' v. Pattern 2 - 'Late afternoon', was not associated with weight status (0·95 (0·65, 1·38)). A daily EI pattern with more and even %TEI peaks at earlier daytime periods, rather than fewer and higher, may be negatively associated with overweight or obesity amongst this population whereas the identified PA patterns might have no relationship.

Association of family meals with sleep and quality of life in Japanese preschool and elementary school children: A cross-sectional study

Sleep is crucial for children's health and eating habits. The decline in family meals has raised concerns about its impact on children. Previous research indicated associations between family meals and psychological health and dietary habits, but their relationship with sleep behavior is less understood. This study examined the association between family meals (breakfast and dinner), sleep patterns, and quality of life among Japanese preschoolers and elementary school students (1st to 3rd grade). The cross-sectional study involved 6,177 children aged 3-8 years in Japan. Mothers completed an online survey on family meal habits, sleep patterns, and the KINDL-R questionnaire to assess quality of life. Results showed that family meals were associated with sleep behaviors and KINDL scores. Multiple regression analysis indicated that family breakfast was associated with earlier bedtime and wake-up time, shorter weekend sleep duration, reduced social jet lag, and a morning chronotype, as detected by the Munich ChronoType Questionnaire. Family dinners were linked to later sleep and wake-up times and an evening chronotype. Family breakfast and dinner were associated with higher KINDL scores, with dinner having a stronger positive impact. These findings underscore the significance of family meals in associating sleep patterns and quality of life among Japanese children.

Exploring factors influencing late evening eating and barriers and enablers to changing to earlier eating patterns in adults with overweight and obesity

Late evening eating is a potential risk factor for overconsumption and weight gain. However, there is limited qualitative research investigating the complex factors that influence late evening eating in adults living with obesity. Identifying the factors that influence late evening eating can inform interventions to reduce late evening eating and associated health risks. Therefore, this study aimed to: i) explore factors that contribute to eating late, and ii) apply the Capability, Opportunity, and Motivation Behaviour (COM-B) model to understand the barriers and enablers to changing to earlier food intake timings in UK adults who report eating late. Semi-structured interviews with seventeen participants [32.47 ± 6.65 years; 34.68 ± 7.10 kg/m2; 71% female (n = 12); 41% White (n = 7)] investigated reasons for late evening eating and the potential barriers and enablers to changing to earlier eating patterns. Thematic analysis identified four main contributors to late evening eating: 1) internal signals (e.g., feeling hungry in the evening); 2) external and situational factors (e.g., work schedules and the food-rich environment); 3) social factors (e.g., interactions with family) and 4) behavioural and emotional factors (e.g., personal preferences and negative feelings in the evening). Time constraints and work schedules were identified as main barriers to changing to earlier eating patterns. Whereas, having high motivation (e.g., contentment with eating earlier in the evening) and interpersonal support were identified as main enablers to eating earlier. This study provides in-depth insights into the psychological, social, and environmental factors contributing to late evening eating. The findings highlight potential targets for future interventions to facilitate earlier eating times in individuals at risk of overweight and obesity.

Time of Energy Intake: Association with Weight Status, Diet Quality, and Sociodemographic Characteristics in Brazil

This study aimed to estimate the association of time of energy intake with weight status, diet quality, and sociodemographic characteristics in Brazil. This cross-sectional study used data from a nationally representative survey with 44.744 individuals (≥10 years old). Food consumption was assessed by 24 h recall. The evening/morning energy intake ratio was calculated, standardized, and categorized in tertiles. The association between the evening/morning energy intake ratio and weight status was estimated using polynomial logistic regression models, and differences across diet quality and sociodemographic categories were estimated considering the non-overlapping 95% confidence intervals. Men, adolescents, adults, and individuals in the higher income level had greater evening energy intake. Those with a higher evening-to-morning energy intake ratio were 15% more likely to be obese (OR = 1.15; 95% CI = 1.02 to 1.28), 21% less likely to be underweight (OR = 0.79; 95% CI = 0.64 to 0.98), and reported greater total energy, protein, and lipid intake, as well as higher consumption of low-quality diet markers. Higher evening energy intake relative to morning intake was associated with obesity, low-quality diet markers, and sociodemographic characteristics. The characterization of the time of energy intake can be useful for tailoring and targeting diet promotion actions and for controlling the obesity epidemic.

Suppression of the postprandial hyperglycemia in patients with type 2 diabetes by a raw medicinal herb powder is weakened when consumed in ordinary hard gelatin capsules: A randomized crossover clinical trial

INTRODUCTION

Contradictory claims about the efficacy of several medicinal plants to promote glycemic control in patients with type 2 diabetes mellitus (T2DM) have been explained by divergences in the administration form and by extrapolation of data obtained from healthy individuals. It is not known whether the antidiabetic effects of traditional herbal medicines are influenced by gelatin capsules. This randomized crossover trial aimed to evaluate the acute effect of a single dose of raw cinnamon consumed orally either dissolved in water as a beverage or as ordinary hard gelatin capsules on postprandial hyperglycemia (>140 mg/dL; >7.8 mmol/L) in T2DM patients elicited by a nutritionally-balanced meal providing 50 g of complex carbohydrates.

METHODS

Fasting T2DM patients (n = 19) randomly ingested a standardized meal in five experimental sessions, one alone (Control) and the other after prior intake of 3 or 6 g of crude cinnamon in the form of hard gelatin capsules or powder dissolved in water. Blood glucose was measured at fasting and at 0.25, 0.5, 0.75, 1, 1.5 and 2 hours postprandially. After each breakfast, its palatability scores for visual appeal, smell and pleasantness of taste were assessed, as well as the taste intensity sweetness, saltiness, bitterness, sourness and creaminess.

RESULTS

The intake of raw cinnamon dissolved in water, independently of the dose, decreased the meal-induced large glucose spike (peak-rise of +87 mg/dL and Δ1-hour glycemia of +79 mg/dL) and the hyperglycemic blood glucose peak. When cinnamon was taken as capsules, these anti-hyperglycemic effects were lost or significantly diminished. Raw cinnamon intake did not change time-to-peak or the 2-h post-meal glycaemia, but flattened the glycemic curve (lower iAUC) without changing the shape that is typical of T2DM patients.

CONCLUSIONS

This cinnamon's antihyperglycemic action confirms its acarbose-like property to inhibit the activities of the carbohydrate-digesting enzymes α-amylases/α-glucosidases, which is in accordance with its exceptionally high content of raw insoluble fiber. The efficacy of using raw cinnamon as a diabetes treatment strategy seems to require its intake at a specific time before/concomitantly the main hyperglycemic daily meals. Trial registration: Registro Brasileiro de Ensaios Clínicos (ReBEC), number RBR-98tx28b.

Eating frequency, timing of meals, and sleep duration before and after a randomized controlled weight loss trial for breast cancer survivors

PURPOSE

To examine eating frequency, timing of meals, and sleep duration before and after a weight loss intervention for breast cancer survivors.

METHODS

Female breast cancer survivors (n = 159; 55 ± 9 years; 31.4 ± 5.0 kg/m2; stage I-III, median [IQR] 9.5 [5.5] months post-diagnosis) participated in a randomized controlled trial of a 12-month weight loss intervention versus usual care. Eating frequency, proportion of daily calories consumed after 5 PM, eating after 8 PM, nightly fasting duration, and sleep duration were estimated and categorized based on existing associations with factors influencing breast cancer prognosis and breast cancer outcomes. These behaviors at baseline were compared to women from an Australian national survey with similar age and BMI range. Mixed-effects linear regression models were used to examine the changes in health behaviors from baseline to 18 months between intervention and usual care groups.

RESULTS

Before the trial, eating after 8 PM (67%) was higher, and short nightly fasting duration (< 13 h, 83%) and long sleep duration (> 9 h/day, 26%) were marginally higher, in breast cancer survivors than women in the national survey (52%, 75%, and 17%, respectively). "Less optimal" eating behaviors and sleep duration tended to co-occur. Behaviors remained unchanged over the 18-month follow-up, irrespective of the study group (p > 0.05; Cohen's effect sizes < 0.3).

CONCLUSIONS

Later timing of eating and long sleep duration were prevalent in breast cancer survivors and continued following a weight loss intervention.

IMPLICATIONS FOR CANCER SURVIVORS

Future multi-behavior interventions in breast cancer survivors should consider specific messages to target eating timing behaviors and sleep.

Daily Brain Metabolic Rhythms of Wild Nocturnal Bats

Circadian rhythms are found in a wide range of organisms and have garnered significant research interest in the field of chronobiology. Under normal circadian function, metabolic regulation is temporally coordinated across tissues and behaviors within a 24 h period. Metabolites, as the closest molecular regulation to physiological phenotype, have dynamic patterns and their relationship with circadian regulation remains to be fully elucidated. In this study, untargeted brain metabolomics was employed to investigate the daily rhythms of metabolites at four time points corresponding to four typical physiological states in Vespertilio sinensis. Key brain metabolites and associated physiological processes active at different time points were detected, with 154 metabolites identified as rhythmic. Analyses of both metabolomics and transcriptomics revealed that several important physiological processes, including the pentose phosphate pathway and oxidative phosphorylation, play key roles in regulating rhythmic physiology, particularly in hunting and flying behaviors. This study represents the first exploration of daily metabolic dynamics in the bat brain, providing insights into the complex regulatory network of circadian rhythms in mammals at a metabolic level. These findings serve as a valuable reference for future studies on circadian rhythms in nocturnal mammals.

Chrononutrition and Cardiometabolic Health: An Overview of Epidemiological Evidence and Key Future Research Directions

Chrononutrition is a rapidly evolving field of nutritional epidemiology that addresses the complex relationship between temporal eating patterns, circadian rhythms, and metabolic health, but most prior research has focused on the cardiometabolic consequences of time-restricted feeding and intermittent fasting. The purpose of this topical review is to summarize epidemiological evidence from observational and intervention studies regarding the role of chrononutrition metrics related to eating timing and regularity in cardiometabolic health preservation and cardiovascular disease prevention. Observational studies are limited due to the lack of time-stamped diet data in most population-based studies. Findings from cohort studies generally indicate that breakfast skipping or the later timing of the first eating occasion, a later lunch and dinner, and a greater proportion of caloric intake consumed in the evening are associated with adverse cardiometabolic outcomes, including higher risk for coronary heart disease, hypertension, type 2 diabetes, obesity, dyslipidemia, and systemic inflammation. Randomized controlled trials are also limited, as most in the field of chrononutrition focus on the cardiometabolic consequences of time-restricted feeding. Overall, interventions that shift eating timing patterns to earlier in the day and that restrict evening caloric intake tend to have protective effects on cardiometabolic health, but small sample sizes and short follow-up are notable limitations. Innovation in dietary assessment approaches, to develop low-cost validated tools with acceptable participant burden that reliably capture chrononutrition metrics, is needed for advancing observational evidence. Culturally responsive pragmatic intervention studies with sufficiently large and representative samples are needed to understand the impact of fixed and earlier eating timing schedules on cardiometabolic health. Additional research is warranted to understand the modifiable determinants of temporal eating patterns, to investigate the role of chrononutrition in the context of other dimensions of diet (quantity, quality, and food and nutrition security) in achieving cardiometabolic health equity, and to elucidate underlying physiological mechanisms.

Personal light exposure patterns and incidence of type 2 diabetes: analysis of 13 million hours of light sensor data and 670,000 person-years of prospective observation

Background

Light at night disrupts circadian rhythms, and circadian disruption is a risk factor for type 2 diabetes. Whether personal light exposure predicts diabetes risk has not been demonstrated in a large prospective cohort. We therefore assessed whether personal light exposure patterns predicted risk of incident type 2 diabetes in UK Biobank participants, using ∼13 million hours of light sensor data.

Methods

Participants (N = 84,790, age (M ± SD) = 62.3 ± 7.9 years, 58% female) wore light sensors for one week, recording day and night light exposure. Circadian amplitude and phase were modeled from weekly light data. Incident type 2 diabetes was recorded (1997 cases; 7.9 ± 1.2 years follow-up; excluding diabetes cases prior to light-tracking). Risk of incident type 2 diabetes was assessed as a function of day and night light, circadian phase, and circadian amplitude, adjusting for age, sex, ethnicity, socioeconomic and lifestyle factors, and polygenic risk.

Findings

Compared to people with dark nights (0-50th percentiles), diabetes risk was incrementally higher across brighter night light exposure percentiles (50-70th: multivariable-adjusted HR = 1.29 [1.14-1.46]; 70-90th: 1.39 [1.24-1.57]; and 90-100th: 1.53 [1.32-1.77]). Diabetes risk was higher in people with lower modeled circadian amplitude (aHR = 1.07 [1.03-1.10] per SD), and with early or late circadian phase (aHR range: 1.06-1.26). Night light and polygenic risk independently predicted higher diabetes risk. The difference in diabetes risk between people with bright and dark nights was similar to the difference between people with low and moderate genetic risk.

Interpretation

Type 2 diabetes risk was higher in people exposed to brighter night light, and in people exposed to light patterns that may disrupt circadian rhythms. Avoidance of light at night could be a simple and cost-effective recommendation that mitigates risk of diabetes, even in those with high genetic risk.

Funding

Australian Government Research Training Program.

It's About Timing: Contrasting the Metabolic Effects of Early vs. Late Time-Restricted Eating in Humans

PURPOSE OF REVIEW

Time-restricted eating (TRE), a form of intermittent fasting, restricts feeding time across the day, imposing a daily 'eating window'. The time of day when the eating window occurs could result in differential metabolic effects. Here, we describe recent intervention studies in humans assessing the metabolic consequences of an early- (i.e., eating window starting in the early morning) vs. late (i.e., eating window starting after midday)-TRE protocol.

RECENT FINDINGS

Well-controlled studies indicate that both TRE protocols effectively reduce body weight and improve altered glucose metabolism, lipid profile, inflammation, or blood pressure levels. An early-TRE (e-TRE) might have a further positive impact on improving blood glucose, insulin levels, and insulin resistance. However, the studies directly assessing the metabolic consequences of an early- vs. late-TRE have shown dissimilar findings, and more well-controlled clinical trials are needed on the metabolic benefits of these two types of TRE. Evidence suggests that an e-TRE might have enhanced metabolic results, particularly regarding glucose homeostasis. More long-term studies, including larger sample sizes, are needed to assess the metabolic, circadian, and adherence benefits, together with socio-cultural acceptance of both TRE approaches.

Meal timing and its role in obesity and associated diseases

Meal timing emerges as a crucial factor influencing metabolic health that can be explained by the tight interaction between the endogenous circadian clock and metabolic homeostasis. Mistimed food intake, such as delayed or nighttime consumption, leads to desynchronization of the internal circadian clock and is associated with an increased risk for obesity and associated metabolic disturbances such as type 2 diabetes and cardiovascular diseases. Conversely, meal timing aligned with cellular rhythms can optimize the performance of tissues and organs. In this review, we provide an overview of the metabolic effects of meal timing and discuss the underlying mechanisms. Additionally, we explore factors influencing meal timing, including internal determinants such as chronotype and genetics, as well as external influences like social factors, cultural aspects, and work schedules. This review could contribute to defining meal-timing-based recommendations for public health initiatives and developing guidelines for effective lifestyle modifications targeting the prevention and treatment of obesity and associated metabolic diseases. Furthermore, it sheds light on crucial factors that must be considered in the design of future food timing intervention trials.

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 (WHtR), 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 3-d 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 (EO); (2) time between the last EO and sleep onset; and (3) percentage of total daily energy intake (%TDEI) consumed 2 h 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 EO 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 WHtR. No associations with BMI Z-score were found after adjustments. Clock time of the last EO 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.

Association between sleep traits and biological aging risk: a Mendelian randomization study based on 157 227 cases and 179 332 controls

STUDY OBJECTIVES

To investigate whether sleep traits are associated with the risk of biological aging using a case-control design with Mendelian randomization (MR) analyses.

METHODS

We studied 336 559 participants in the UK Biobank cohort, including 157 227 cases of accelerated biological aging and 179 332 controls. PhenoAge, derived from clinical traits, estimated biological ages, and the discrepancies from chronological age were defined as age accelerations (PhenoAgeAccel). Sleep behaviors were assessed with a standardized questionnaire. propensity score matching matched control participants to age-accelerated participants, and a conditional multivariable logistic regression model estimated odds ratio (OR) and 95% confidence intervals (95% CI). Causal relationships between sleep traits and PhenoAgeAccel were explored using linear and nonlinear MR methods.

RESULTS

A U-shaped association was found between sleep duration and PhenoAgeAccel risk. Short sleepers had a 7% higher risk (OR = 1.07; 95% CI: 1.03 to 1.11), while long sleepers had an 18% higher risk (OR = 1.18; 95% CI: 1.15 to 1.22), compared to normal sleepers (6-8 hours/day). Evening chronotype was linked to higher PhenoAgeAccel risk than morning chronotype (OR = 1.14; 95% CI: 1.10 to 1.18), while no significant associations were found for insomnia or snoring. Morning chronotype had a protective effect on PhenoAgeAccel risk (OR = 0.87, 95% CI: 0.79 to 0.95) per linear MR analysis. Genetically predicted sleep duration showed a U-shaped relationship with PhenoAgeAccel, suggesting a nonlinear association (pnonlinear < 0.001).

CONCLUSIONS

The study suggests that improving sleep can slow biological aging, highlighting the importance of optimizing sleep as an intervention to mitigate aging's adverse effects.

Night eating in timing, frequency, and food quality and risks of all-cause, cancer, and diabetes mortality: findings from national health and nutrition examination survey

OBJECTIVE

To investigate the association of timing, frequency, and food quality of night eating with all-cause, cancer, and diabetes mortality.

METHODS

This study included 41,744 participants from the US National Health and Nutrition Examination Survey (2002-2018). Night eating information was collected by 24-h dietary recall and the exposures were timing, frequency, and food quality of night eating. Food quality was assessed by latent class analysis. The outcomes were all-cause, cancer, and diabetes mortality, which were identified by the National Death Index and the International Classification of Diseases 10th Revision. Adjusted hazard ratios [aHR] with 95% confidence intervals [CI] were computed by Cox regression.

RESULTS

During a median follow-up of 8.7 years, 6066 deaths were documented, including 1381 from cancer and 206 from diabetes. Compared with no night eating (eating before 22:00), the later timing of night eating was associated with higher risk of all-cause and diabetes mortality (each P-trend <0.05) rather than cancer mortality, with the highest risk of eating being 00:00-1:00 (aHR 1.38, 95% CI 1.02-1.88) and being 23:00-00:00 (aHR 2.31, 95% CI 1.21-4.40), respectively. However, the increased risks were not observed for 22:00-23:00. Likewise, one time or over frequency of night eating was associated with higher all-cause and diabetes mortality (each P < 0.05). That risks were further observed in high-dietary-energy-density group of night eating (all-cause mortality: aHR 1.21 [95% CI 1.06-1.38]; diabetes mortality: aHR 1.97 [95% CI 1.13-3.45]), but not in low-dietary-energy-density group. Finally, correlation analysis found positive associations of night eating with glycohemoglobin, fasting glucose, and OGTT.

CONCLUSIONS

Night eating was associated with increased all-cause, cancer and diabetes mortality; however, reduction of excess mortality risk was observed when eating before 23:00 or low-dietary-energy-density foods.

Advances in Understanding the Interplay between Dietary Practices, Body Composition, and Sports Performance in Athletes

The dietary practices of athletes play a crucial role in shaping their body composition, influencing sports performance, training adaptations, and overall health. However, despite the widely acknowledged significance of dietary intake in athletic success, there exists a gap in our understanding of the intricate relationships between nutrition, body composition, and performance. Furthermore, emerging evidence suggests that many athletes fail to adopt optimal nutritional practices, which can impede their potential achievements. In response, this Special Issue seeks to gather research papers that delve into athletes' dietary practices and their potential impacts on body composition and sports performance. Additionally, studies focusing on interventions aimed at optimizing dietary habits are encouraged. This paper outlines the key aspects and points that will be developed in the ensuing articles of this Special Issue.

Sleep Variability, Eating Timing Variability, and Carotid Intima-Media Thickness in Early Adulthood

Background Day-to-day variability in sleep patterns and eating timing may disrupt circadian rhythms and has been linked with various adverse cardiometabolic outcomes. However, the extent to which variability in sleep patterns and eating timing relate to atherosclerotic development in subclinical stages remains unclear. Methods and Results Generally healthy adults (N=62, 29.3±7.3 years, 66% female) completed 14 days of sleep and dietary assessments via wrist accelerometry and photo-assisted diet records, respectively. Variability in sleep duration, sleep onset, eating onset (time of first caloric consumption), eating offset (time of last caloric consumption), and caloric midpoint (time at which 50% of total daily calories are consumed) were operationalized as the SD across 14 days for each variable. Separate regression models evaluated the cross-sectional associations between sleep and eating variability metrics with end-diastolic carotid intima-media thickness (CIMT) measured via ultrasonography. Models adjusted for age, sex, systolic blood pressure, sleep duration, and total energy intake. Each 60-minute increase in sleep duration SD and sleep onset SD were associated with a 0.049±0.016 mm (P=0.003) and 0.048±0.017 mm (P=0.007) greater CIMT, respectively. Variability in eating onset and offset were not associated with CIMT; however, each 60-minute increase in caloric midpoint SD was associated with a 0.033±0.015 mm greater CIMT (P=0.029). Exploratory post hoc analyses suggested that sleep duration SD and sleep onset SD were stronger correlates of CIMT than caloric midpoint SD. Conclusions Variability in sleep patterns and eating timing are positively associated with clinically relevant increases in CIMT, a biomarker of subclinical atherosclerosis, in early adulthood.

Stress during Home Confinement Is Associated with Eating Misalignment among Adults during COVID-19 Lockdown

BACKGROUND

The COVID-19 pandemic forced Saudi Arabia to implement several measures including mandatory home confinement, banning entry to many cities, and suspending religious activities. Studies have reported inconsistent findings of the effect of home confinement on lifestyle factors. This study aims to assess the psychological impact of COVID-19 during home confinement and explore its association with dietary habits and weight change.

METHODS

A cross-sectional study was conducted among Saudi adults using an online survey between May and June 2020. Data on dietary habits, sleep quality, and stress were collected.

RESULTS

A total of n = 503 participants responded. Of 254 analyzed, 87% were females, 49% were overweight/obese (body mass index (BMI) ≥ 25 kg/m2), and 79% were under lockdown for >40 days. In multiple linear regression, higher stress scores during confinement were associated with higher stress scores before confinement and poorer sleep quality. In multiple logistic regression, those who did not eat at the same time had higher stress scores compared to those who always ate at the same time, whereas consuming ≥three meals was associated with lower stress scores than consuming one-two meals. The odds of gaining weight during confinement were higher among married adults, those with lower sleep quality, and consuming ≥three meals.

CONCLUSIONS

Stress during home confinement was associated with eating misalignment and the number of meals consumed. Although this study was limited by its cross-sectional design and reliance on self-reported data, it provides valuable insights into the dietary habits and weight-gain associated factors that need to be further explored and addressed in any future restrictions for improved well-being.

Timing Matters: The Interplay between Early Mealtime, Circadian Rhythms, Gene Expression, Circadian Hormones, and Metabolism-A Narrative Review

Achieving synchronization between the central and peripheral body clocks is essential for ensuring optimal metabolic function. Meal timing is an emerging field of research that investigates the influence of eating patterns on our circadian rhythm, metabolism, and overall health. This narrative review examines the relationship between meal timing, circadian rhythm, clock genes, circadian hormones, and metabolic function. It analyzes the existing literature and experimental data to explore the connection between mealtime, circadian rhythms, and metabolic processes. The available evidence highlights the importance of aligning mealtime with the body's natural rhythms to promote metabolic health and prevent metabolic disorders. Specifically, studies show that consuming meals later in the day is associated with an elevated prevalence of metabolic disorders, while early time-restricted eating, such as having an early breakfast and an earlier dinner, improves levels of glucose in the blood and substrate oxidation. Circadian hormones, including cortisol and melatonin, interact with mealtimes and play vital roles in regulating metabolic processes. Cortisol, aligned with dawn in diurnal mammals, activates energy reserves, stimulates appetite, influences clock gene expression, and synchronizes peripheral clocks. Consuming meals during periods of elevated melatonin levels, specifically during the circadian night, has been correlated with potential implications for glucose tolerance. Understanding the mechanisms of central and peripheral clock synchronization, including genetics, interactions with chronotype, sleep duration, and hormonal changes, provides valuable insights for optimizing dietary strategies and timing. This knowledge contributes to improved overall health and well-being by aligning mealtime with the body's natural circadian rhythm.

The Effect of Early Time-Restricted Eating vs Later Time-Restricted Eating on Weight Loss and Metabolic Health

CONTEXT

It remains controversial whether the choice of the daily eating window early or later in time-restricted eating (TRE) intervention (early or later TRE) has different effects on weight loss and metabolic health.

OBJECTIVE

A network meta-analysis was performed to evaluate the efficacy between early and later TRE in adults with obesity or overweight.

METHODS

We searched PubMed, Embase, Web of Science, and Cochrane Library for randomized controlled trials (RCTs) published until October 16, 2022. We conducted a network meta-analysis to evaluate the efficacy of early and later TRE on body weight and metabolic parameters, including glycemic metabolism, blood pressure, and lipid profiles.

RESULTS

Twelve RCTs with 730 obese or overweight adults were included in this meta-analysis. Early TRE and later TRE both elicited moderate reductions in body weight and insulin resistance (IR) (homeostasis model assessment of IR) when compared to non-TRE. Interestingly, early TRE showed more effectiveness than later TRE in improving IR (early vs later TRE: -0.44; 95% CI, -0.86 to -0.02; P < .05), whereas no statistically significant difference was detected in weight loss (early vs later TRE: -0.31 kg; 95% CI, -1.15 to 0.53 kg; P >.05). In addition, early TRE rather than later TRE showed significant benefits in glycemic metabolism and blood pressure when compared to non-TRE. No significant differences between early and later TRE were observed for fasting blood glucose, blood pressure, and lipid profiles.

CONCLUSION

This meta-analysis suggests that people may choose early TRE for more effective weight management and metabolic benefits. Nevertheless, further large-scale RCTs are warranted to verify our findings.

Associations of timing of food intake with energy intake, eating behaviour traits and psychosocial factors in adults with overweight and obesity

Introduction

Whether a late distribution of food intake impacts obesity through increased energy intake remains uncertain and the behavioural characterization of late eating needs to be further investigated. The first objective of this study was to assess the associations between late eating and body mass index (BMI) and total energy intake (TEI), and whether TEI mediates the association between late eating and BMI. The second objective was to assess the associations between late eating and eating behaviour traits or psychosocial factors and whether eating behaviour traits mediate the association between late eating and TEI.

Methods

Baseline data from 301 individuals (56% women, age = 38.7 ± 8.5 years; BMI = 33.2 ± 3.4 kg/m²), who participated in four weight loss studies were used in this cross-sectional study. Total energy intake was assessed using a three-day food record from which the percentage of TEI after 17:00 and after 20:00 was calculated. Eating behaviour traits and psychosocial factors were assessed with questionnaires. Pearson correlations and mediation analyses adjusted for age, sex, underreporting of energy intake, sleep duration and bedtime were performed.

Results

Percent TEI after 17:00 and after 20:00 were associated with TEI (r = 0.13, p = 0.03 for both), and TEI mediated the association between percent TEI after 17:00 and BMI (β = 0.01 ± 0.01, 95% CI: 0.001, 0.02). Percent TEI after 17:00 was associated with disinhibition (r = 0.13, p = 0.03) and percent TEI after 20:00 was associated with susceptibility to hunger (r = 0.13, p = 0.03), stress (r = 0.24, p = 0.002) and anxiety (r = 0.28, p = 0.0004). In women, disinhibition mediated the association between percent TEI after 17:00 and TEI (β = 3.41 ± 1.43, 95% CI: 0.92, 6.47). Susceptibility to hunger mediated the association between percent TEI after 20:00 and TEI (β = 0.96 ± 0.59, 95% CI: 0.02, 2.34) in men and women.

Conclusion

Late eating is associated with TEI and suboptimal eating behaviours which could contribute to explaining the association between timing of food intake and obesity.

Effects of Irregular Mealtimes on Social and Eating Jet Lags among Japanese College Students

College students' social and eating jet lags and chronotypes may be related to irregular eating habits. Therefore, we examined the relationship between social and eating jet lags, chronotypes, variability in first and last mealtimes, and non-eating duration, as well as the effects of snacking between dinner and bedtime on social and eating jet lags, chronotypes, and mealtime variation. A total of 1900 Japanese male college students were recruited in this study. Mean wake-up time, bedtime, sleeping time, first and last mealtimes, snacks between meals, non-eating duration, the midpoint of non-eating duration, social and eating jet lags, and chronotype were calculated. Standard deviations in first and last mealtimes, the midpoint of non-eating duration, and the coefficient of variation in non-eating duration were used to evaluate mealtime variations. Mealtime variations were significantly associated with social and eating jet lags, chronotype, the midpoint of non-eating duration, and the difference in first and last mealtime between school holidays and class days. Chronotype and the midpoint of non-eating duration were significantly delayed with increased snacking after dinner. Mealtime variations were significantly lower in those who avoided snacking than in those who did not. Thus, social and eating jet lags and chronotypes are associated with sleep habits and mealtime irregularities.

Association of meal timing with body composition and cardiometabolic risk factors in young adults

PURPOSE

To investigate the association of meal timing with body composition and cardiometabolic risk factors in young adults.

METHODS

In this cross-sectional study participated 118 young adults (82 women; 22 ± 2 years old; BMI: 25.1 ± 4.6 kg/m²). Meal timing was determined via three non-consecutive 24-h dietary recalls. Sleep outcomes were objectively assessed using accelerometry. The eating window (time between first and last caloric intake), caloric midpoint (local time at which ≥ 50% of daily calories are consumed), eating jetlag (variability of the eating midpoint between non-working and working days), time from the midsleep point to first food intake, and time from last food intake to midsleep point were calculated. Body composition was determined by DXA. Blood pressure and fasting cardiometabolic risk factors (i.e., triglycerides, total cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, and insulin resistance) were measured.

RESULTS

Meal timing was not associated with body composition (p > 0.05). The eating window was negatively related to HOMA-IR and cardiometabolic risk score in men (R² = 0.348, β = - 0.605; R² = 0.234, β = - 0.508; all p ≤ 0.003). The time from midsleep point to first food intake was positively related to HOMA-IR and cardiometabolic risk score in men (R² = 0.212, β = 0.485; R² = 0.228, β = 0.502; all p = 0.003). These associations remained after adjusting for confounders and multiplicity (all p ≤ 0.011).

CONCLUSIONS

Meal timing seems unrelated to body composition in young adults. However, a longer daily eating window and a shorter time from midsleep point to first food intake (i.e., earlier first food intake in a 24 h cycle) are associated with better cardiometabolic health in young men.

CLINICAL TRIAL REGISTRATION

NCT02365129 ( https://www.

CLINICALTRIALS

gov/ct2/show/NCT02365129?term=ACTIBATE&draw=2&rank=1 ).

Can Circadian Eating Pattern Adjustments Reduce Risk or Prevent Development of T2D?

Type 2 diabetes (T2D) is a chronic condition that occurs in insulin-resistant people with reduced glucose uptake. It is contributed to and exacerbated by a poor diet that results in accumulation of adipose tissue, high blood sugar, and other metabolic issues. Because humans have undergone food scarcity throughout history, our species has adapted a fat reserve genotype. This adaptation is no longer beneficial, as eating at a higher frequency than that of our ancestors has had a significant effect on T2D development. Eating at high frequencies disrupts the circadian clock, the circadian rhythm, and the composition of the gut microbiome, as well as hormone secretion and sensitivity. The current literature suggests an improved diet requires meal consistency, avoiding late-night eating, low meal frequency, and fasting to increase metabolic health. In addition, fasting as a treatment for T2D must be used correctly for beneficial results. Early time-restricted eating (TRE) provides many benefits such as improving insulin resistance, cognitive function, and glycemic control. Alternate-day fasting (ADF), 5:2 fasting, and long-term fasting all have benefits; however, they may be less advantageous than early TRE. Therefore, eating pattern adjustments can be used to reduce T2D if used correctly.

Association between Late-Eating Pattern and Higher Consumption of Ultra-Processed Food among Italian Adults: Findings from the INHES Study

Late eating is reportedly associated with adverse metabolic health, possibly through poor diet quality. We tested the hypothesis that meal timing could also be linked to food processing, an independent predictor of health outcomes. We analysed data on 8688 Italians (aged > 19years) from the Italian Nutrition & HEalth Survey (INHES) established in 2010-2013 throughout Italy. Dietary data were collected through a single 24 h dietary recall, and the NOVA classification was used to categorize foods according to increasing levels of processing: (1) minimally processed foods (e.g., fruits); (2) culinary ingredients (e.g., butter); (3) processed foods (e.g., canned fish); (4) ultra-processed foods (UPFs; e.g., carbonated drinks, processed meat). We then calculated the proportion (%) of each NOVA group on the total weight of food eaten (g/d) by creating a weight ratio. Subjects were classified as early or late eaters based on the population's median timing for breakfast, lunch and dinner. In multivariable-adjusted regression models, late eaters reported a lower intake of minimally processed food (β = -1.23; 95% CI -1.75 to -0.71), a higher intake of UPF (β = 0.93; 0.60 to 1.25) and reduced adherence to a Mediterranean Diet (β = -0.07; -0.12 to -0.03) as compared to early eaters. Future studies are warranted to examine whether increased UPF consumption may underpin the associations of late eating with adverse metabolic health reported in prior cohorts.

Weight status of working adults: The effects of eating misalignment, chronotype, and eating jetlag during mandatory confinement

This study aimed to examine the association between chronotype, eating jetlag, and eating misalignment with weight status among Malaysian adults during the COVID-19 restriction. This online cross-sectional study included 175 working adults recruited from March to July 2020. The chronotype was assessed using Morningness Eveningness Questionnaire (MEQ) while eating jetlag and mealtime variability were measured using Chrononutrition Profile Questionnaire (CPQ). Multiple linear regression demonstrated that lower breakfast frequency (β=-0.258, p = .002) and longer eating duration (β = 0.393, p < .001) were associated with later first eating events on workfree days. Both intermediate (β = 0.543, p < .001) and evening chronotypes (β = 0.523, p = .001) tend to eat their first meals later compared to morning person. Similar patterns were observed for overall eating jetlaggers in which lower breakfast frequency (β=-0.022, p = .011), longer eating duration (β = 0.293, p < .001), intermediate chronotype (β = 0.512, p < .001), and evening chronotype (β = 0.495, p = .003) were associated with eating later meals on workfree days. Additionally, higher BMI was also associated with eating later meals on workfree days (β = 0.181, p = .025). During movement restriction, discrepancies of mealtimes during work and workfree days offer new insight into modern eating habits that can influence weight status and general eating habits such as breakfast skipping and total daily eating duration. Population meal timing variability was affected during movement restrictions, and it was closely related to weight status.

When should I eat: A circadian view on food intake and metabolic regulation

The circadian clock is a hierarchical timing system regulating most physiological and behavioral functions with a period of approximately 24 h in humans and other mammalian species. The circadian clock drives daily eating rhythms that, in turn, reinforce the circadian clock network itself to anticipate and orchestrate metabolic responses to food intake. Eating is tightly interconnected with the circadian clock and recent evidence shows that the timing of meals is crucial for the control of appetite and metabolic regulation. Obesity results from combined long-term dysregulation in food intake (homeostatic and hedonic circuits), energy expenditure, and energy storage. Increasing evidence supports that the loss of synchrony of daily rhythms significantly impairs metabolic homeostasis and is associated with obesity. This review presents an overview of mechanisms regulating food intake (homeostatic/hedonic) and focuses on the crucial role of the circadian clock on the metabolic response to eating, thus providing a fundamental research axis to maintain a healthy eating behavior.

Improvement in chrono-nutrition is associated with robust weight loss outcomes: An extension of the feasibility study

Previously we had demonstrated the development and feasibility of an integrated chrono-nutrition weight reduction program among non-shift workers with morning and evening chronotypes. In this current paper, we described the association between the changes in chrono-nutrition practice and weight loss outcomes upon completing the weight reduction program. A total of 91 overweight/obese non-shift workers participated in the 12-week integrated chrono-nutrition weight reduction program (Age: 39.6 ± 6.3 y; 74.7% women; BMI: 31.2 ± 4.5 kg/m²). All the assessments including anthropometry, dietary, sleep habits, physical activity, and process of change were measured during pre- and post-intervention. Participants who had lost ≥3% of their body weight were categorized as satisfactory weight loss outcome, and those who did not achieve 3% weight loss were categorized as unsatisfactory weight loss. The satisfactory weight loss had greater daily percent energy intake during earlier in the day from protein (Mean difference (MD): +3.2%, 95% CI: 1.6, 4.9, p < .001) and smaller intake from fat during later in the day (MD: -2.6%, 95% CI: -5.1, -0.1, p = .045), earlier last mealtime (MD: -49.5 min, 95% CI: -86.5, -12.6, p = .009) and midpoint of eating (MD: -27.3 min, 95% CI: -46.3, -8.2, p = .006), shorter eating window (-0.8 h, 95% CI: -1.4, -0.1, p = .031) and greater reduction in night eating syndrome score (MD: -2.4, 95% CI: -4.3, -0.5, p = .015) compared to unsatisfactory weight loss outcome. After accounting for potential confounders, the temporal pattern of energy, protein, and fat intake were associated with greater odds of achieving a satisfactory weight loss. The findings suggest a promising role of chrono-nutrition as one of the strategies in weight reduction intervention.

Association between shift rotation and 30-year Framingham risk of cardiovascular disease among male workers in a medium-sized manufacturing factory

Rotating shift work is associated with an increased risk of cardiovascular disease (CVD). This study compared the CVD risk score in 129 male line workers aged 22-49 years on different shifts in a medium-sized metal production factory from 2017 to 2020. We classified workers into four groups: permanent day shift, weekly rotation involving five consecutive nights, weekly rotation involving 3-4 consecutive nights, and monthly rotation involving two consecutive nights. We used the Framingham Risk Score to estimate the 30-yr risks of general and hard CVD (CVD risk estimates). We investigated the differences in CVD risk estimates between different groups using linear mixed models. The average 30-yr Framingham CVD risk estimates of each group ranged from 17.5% to 31.2% for general CVD and from 10.5% to 20.5% for hard CVD. Workers on weekly rotations involving 3-5 consecutive nights had 5%-10% significantly higher CVD risk estimates than workers on the permanent day shift. Workers on weekly rotations also had 6%-8% higher BMI-based CVD risk estimates than those on the monthly rotation involving two consecutive nights. While 24-h shift rotations are unavoidable, our findings underscored the potential CVD risk among workers on weekly rotations involving more consecutive nights.

Research gaps and opportunities in precision nutrition: an NIH workshop report

Precision nutrition is an emerging concept that aims to develop nutrition recommendations tailored to different people's circumstances and biological characteristics. Responses to dietary change and the resulting health outcomes from consuming different diets may vary significantly between people based on interactions between their genetic backgrounds, physiology, microbiome, underlying health status, behaviors, social influences, and environmental exposures. On 11-12 January 2021, the National Institutes of Health convened a workshop entitled "Precision Nutrition: Research Gaps and Opportunities" to bring together experts to discuss the issues involved in better understanding and addressing precision nutrition. The workshop proceeded in 3 parts: part I covered many aspects of genetics and physiology that mediate the links between nutrient intake and health conditions such as cardiovascular disease, Alzheimer disease, and cancer; part II reviewed potential contributors to interindividual variability in dietary exposures and responses such as baseline nutritional status, circadian rhythm/sleep, environmental exposures, sensory properties of food, stress, inflammation, and the social determinants of health; part III presented the need for systems approaches, with new methods and technologies that can facilitate the study and implementation of precision nutrition, and workforce development needed to create a new generation of researchers. The workshop concluded that much research will be needed before more precise nutrition recommendations can be achieved. This includes better understanding and accounting for variables such as age, sex, ethnicity, medical history, genetics, and social and environmental factors. The advent of new methods and technologies and the availability of considerably more data bring tremendous opportunity. However, the field must proceed with appropriate levels of caution and make sure the factors listed above are all considered, and systems approaches and methods are incorporated. It will be important to develop and train an expanded workforce with the goal of reducing health disparities and improving precision nutritional advice for all Americans.

Keeping an eye on circadian time in clinical research and medicine

BACKGROUND

Daily rhythms are observed in humans and almost all other organisms. Most of these observed rhythms reflect both underlying endogenous circadian rhythms and evoked responses from behaviours such as sleep/wake, eating/fasting, rest/activity, posture changes and exercise. For many research and clinical purposes, it is important to understand the contribution of the endogenous circadian component to these observed rhythms.

CONTENT

The goal of this manuscript is to provide guidance on best practices in measuring metrics of endogenous circadian rhythms in humans and promote the inclusion of circadian rhythms assessments in studies of health and disease. Circadian rhythms affect all aspects of physiology. By specifying minimal experimental conditions for studies, we aim to improve the quality, reliability and interpretability of research into circadian and daily (i.e., time-of-day) rhythms and facilitate the interpretation of clinical and translational findings within the context of human circadian rhythms. We describe protocols, variables and analyses commonly used for studying human daily rhythms, including how to assess the relative contributions of the endogenous circadian system and other daily patterns in behaviours or the environment. We conclude with recommendations for protocols, variables, analyses, definitions and examples of circadian terminology.

CONCLUSION

Although circadian rhythms and daily effects on health outcomes can be challenging to distinguish in practice, this distinction may be important in many clinical settings. Identifying and targeting the appropriate underlying (patho)physiology is a medical goal. This review provides methods for identifying circadian effects to aid in the interpretation of published work and the inclusion of circadian factors in clinical research and practice.

A qualitative exploration of facilitators and barriers of adherence to time-restricted eating

Time-restricted eating (TRE), a dietary strategy that involves limiting daily energy intake to a window of ≤12 h is appealing for weight management and metabolic health due to its relative simplicity and the ability to consume ad libitum diet during eating windows. Despite the potential utility of TRE for improving health and reducing disease, the feasibility of adherence depends upon a variety of multilevel factors which are largely unexplored. The primary aim of our study was to explore facilitators and barriers of adherence to TRE among community-dwelling individuals. Semi-structured qualitative interviews were conducted among 24 individuals (50% male; M age: 34, range: 18-57; 58% overweight/obese) who currently or formerly practiced TRE. Thematic analysis identified facilitators of and barriers to TRE adherence at multiple levels of influence (i.e., biological, behavioral, psychosocial, environmental). Key facilitators of adherence included improvements in physical health and energy levels, alignment with other aspects of diet, exercise and sleep patterns, self-monitoring and positive psychological impacts, social support, and busy or regular schedules. Key barriers included negative physical health effects, feelings of hunger and sluggishness, difficulty in skipping valued baseline eating routines or inadequate diet quality during the eating window, misalignment of TRE with 24-h activity behaviors, difficulties with self-monitoring, the need to mitigate negative feelings, social situations that discourage TRE, and irregular or idle schedules. Results illustrate that key drivers of adherence differ across individuals and their unique settings and that multiple drivers of behavior should be considered in the successful implementation of TRE. Findings may inform interventions seeking to tailor TRE schedules to fit individuals' diverse behavioral patterns and preferences, thereby optimizing adherence.

Wearable Cameras Reveal Large Intra-Individual Variability in Timing of Eating among Young Adults

Studies have shown that young adults follow less structured eating patterns compared with older cohorts. This may have implications for dietary assessment methods which rely on memory and structured meal patterns. Our aim was to describe the intra-individual variation of eating times in young adults aged 18−30 years. Participants (n = 41) wore an Autographer camera that captured first-person perspective images every 30 s for three consecutive days. All images were timestamped and those showing food consumption were used to extract data such as the timing of the first and last eating occasions (EOs), number of EOs per day, and length of eating window. Intra-individual variability was calculated from these data using composite phase deviation (CPD) and coefficient of variation (CV). The number of individuals with high or very high variability was 28 and 18 for timing of first and last EOs, respectively (CPD > 1.70), and 27 and 17 for number of EOs and eating window, respectively (CV > 20%). In this sample of young adults, the lack of regularity in eating patterns should be considered when selecting a dietary assessment method.

Is There a Utility of Chrono-Specific Diets in Improving Cardiometabolic Health?

Modern lifestyle is generally associated with the consumption of three main meals per day, one of which is typically in the evening or at night. It is also well established that consumption of meals in the later part of the day, notably in the evenings, is associated with circadian desynchrony, which in turn increases the risk of non-communicable diseases, particularly cardiometabolic diseases. While it is not feasible to avoid food consumption during the evenings altogether, there is an opportunity to provide chrono-specific, diet-based solutions to mitigate some of these risks. To date, there has been substantial progress in the understanding of chrononutrition, with evidence derived mainly from in vitro and in vivo animal studies. Some of these approaches include the manipulation of the quality and quantity of certain nutrients to be consumed at specific times of the day, as well as incorporating certain dietary components (macronutrients, micronutrients, or non-nutrient bioactives, including polyphenols) with the ability to modulate circadian rhythmicity. However, robust human studies are generally lacking. In this review, the study has consolidated and critically appraised the current evidence base, with an aim to translate these findings to improve cardiometabolic health and provides recommendations to move this field forward.

The Effect of Personality on Chrononutrition during the COVID-19 Lockdown in Qatar

The COVID-19 lockdown has had a significant impact on people's lives worldwide. This study aimed to investigate the effect of personality on chrononutrition during the COVID-19 lockdown. Using a cross-sectional design, a convenient sample of 543 adults in Qatar completed an online questionnaire using validated tools to assess personality and chrononutrition behaviors during the first COVID-19 lockdown. Participants scoring high in openness were more likely to eat at night (mean difference (MD) = 0.41, 95% confidence interval (CI): 0.10, 0.72) compared to those scoring high in agreeableness, while those scoring high in extraversion and openness had a shorter eating window (MD = -76.6, 95%CI: -146.3, -6.93 and MD = -29.8, 95%CI: -56.5, -3.01, respectively). Participants high in extraversion had longer evening latency (MD = 66.3, 95%CI: 25.4, 107.3) and evening eating (MD = -62.0, 95%CI: -114.0, -9.0) compared those high in agreeableness. Participants high in conscientiousness showed evidence of first eating event misalignment during the weekend (MD = 22.0, 95%CI: 0.15, 43.9) and last eating event misalignment during weekdays (MD = -27.8, 95%CI: -47.3, -8.41) compared to those high in agreeableness. Lastly, participants high in openness showed evidence of eating window misalignment during the weekend (MD = 30.6, 95%CI: 5.01, 56.2). This study suggests that personality traits can inform personalized nutritional approaches when aiming for healthy habits during unexpected periods, such as the COVID-19 pandemic.

[Time-restricted eating as a novel strategy for treatment of obesity and it's comorbid conditions]

The article provides a review of the current literature about time-restricted eating (TRE) as a new tool for the treatment of obesity and comorbid conditions. The search for new nutritional strategies in obesity, one of which is TRE, is due to the weak adherence of patients to hypocaloric diets in the long term, as well as the available data on the importance of -desynchronization of food intake with natural circadian rhythms in the development and progression of obesity and cardio--metabolic complications. The article describes the main mechanisms that regulate the circadian rhythms of food intake and nutrient absorption, substantiates the importance of adhering to a physiological diet for maintaining metabolic health. The main part of the review is devoted to reviewing the currently available researches on the effectiveness of various strategies of intermittent energy restriction for weight loss and the correction of metabolic parameters. Potential mechanisms of  the -effect of TRE on health are discussed, including those mediated by an unintentional decrease in caloric intake and changes in eating behavior, and differences in the effectiveness of early and late TRE. The article contains a detailed discussion of the potential problems and contradictions associated with the use of time-restricted eating in clinical practice, namely: the limitations and inconsistencies of the available clinical trials, the lack of data on long-term efficacy and safety, social and psychological limitations that impede the widespread use of TRE.

Circadian Variation of Blood Pressure in Patients with Chronic Musculoskeletal Pain: A Cross-Sectional Study

The aim of this study was to analyze the impact of circadian variation of blood pressure (BP) in patients with chronic musculoskeletal pain (CPM). A further purpose was to study differences in circadian variation of BP between genders and the correlation between BP circadian variation and pain. We performed a cross-sectional, observational study in which seventy-five participants with CMP participated. Circadian variation in BP was calculated using the diurnal/nocturnal BP ratio, and all participants used validated self-measurement BP devices. The Numeric Pain Rating Scale was used to assess pain perception. All circadian BP values from participants who suffered from CPM followed pathologic cardiovascular parameters (BP ratio < 10%). When comparing BP ratios between genders, statistically significant differences were found (p = 0.011). BP itself did not correlate with pain in any subgroup. Circadian variations of BP in those suffering from CMP are shown and new possibilities of research and treatment are proposed.

Perspectives: on Precision Nutrition Research in Heart, Lung, and Blood Diseases and Sleep Disorders

The release of the 2020-2030 Strategic Plan for NIH Nutrition Research (SPNR) and its emphasis on precision nutrition has provided an opportunity to identify future nutrition research that addresses individual variability in response to diet and nutrition across the life span-including those relevant to the Strategic Vision of the National Heart, Lung, and Blood Institute (NHLBI). The SPNR and the NHLBI's Strategic Vision were developed with extensive input from the extramural research community, and both have 4 overarching strategic goals within which are embedded several objectives for research. For the SPNR, these include 1) spur discovery science and normal biological functions (e.g., role of the microbiome in health and disease), 2) population science to understand individual differences (e.g., biomarkers including 'omics that predict disease status), 3) emerging scientific areas of investigation and their application (e.g., data science, artificial intelligence), and 4) cross-cutting themes (e.g., training the scientific workforce and minority health and health disparities). These strategic goals and objectives serve as blueprints for research and training. Nutrition remains important in the prevention and treatment of heart, lung, blood, and sleep (HLBS) disorders and diseases, and the NHLBI has played a pivotal role in supporting nutrition research. In this paper, we report important gaps in the scientific literature related to precision nutrition in HLBS diseases. Research opportunities that could stimulate precision nutrition and their alignment with the SPNR and the NHLBI Strategic Vision Objectives are provided. These opportunities include 1) exploring individual differences in response to varying dietary patterns and nutrients; 2) investigating genetic/epigenetic, biological (e.g., microbiome, biomarkers), social, psychosocial, and environmental underpinnings of individual variability in diet; 3) elucidating the role of circadian rhythm and chrononutrition; and 4) applying implementation science research methods in precision nutrition interventions relevant to HLBS diseases.

Enhancing Nutrition Care Through Real-Time, Sensor-Based Capture of Eating Occasions: A Scoping Review

As food intake patterns become less structured, different methods of dietary assessment may be required to capture frequently omitted snacks, smaller meals, and the time of day when they are consumed. Incorporating sensors that passively and objectively detect eating behavior may assist in capturing these eating occasions into dietary assessment methods. The aim of this study was to identify and collate sensor-based technologies that are feasible for dietitians to use to assist with performing dietary assessments in real-world practice settings. A scoping review was conducted using the PRISMA extension for scoping reviews (PRISMA-ScR) framework. Studies were included if they were published between January 2016 and December 2021 and evaluated the performance of sensor-based devices for identifying and recording the time of food intake. Devices from included studies were further evaluated against a set of feasibility criteria to determine whether they could potentially be used to assist dietitians in conducting dietary assessments. The feasibility criteria were, in brief, consisting of an accuracy ≥80%; tested in settings where subjects were free to choose their own foods and activities; social acceptability and comfort; a long battery life; and a relatively rapid detection of an eating episode. Fifty-four studies describing 53 unique devices and 4 device combinations worn on the wrist (n = 18), head (n = 16), neck (n = 9), and other locations (n = 14) were included. Whilst none of the devices strictly met all feasibility criteria currently, continuous refinement and testing of device software and hardware are likely given the rapidly changing nature of this emerging field. The main reasons devices failed to meet the feasibility criteria were: an insufficient or lack of reporting on battery life (91%), the use of a limited number of foods and behaviors to evaluate device performance (63%), and the device being socially unacceptable or uncomfortable to wear for long durations (46%). Until sensor-based dietary assessment tools have been designed into more inconspicuous prototypes and are able to detect most food and beverage consumption throughout the day, their use will not be feasible for dietitians in practice settings.

Chronodisruption and diet associated with increased cardiometabolic risk in coronary heart disease patients: the CORDIOPREV study

Individuals with evening chronotypes are prone to suffer chronodisruption and display worse lifestyle habits than morning-types, exhibiting higher cardiovascular diseases (CVD). However, it is unknown whether CVD patients, who are evening chronotypes, have higher cardiometabolic risk than morning-types. This study explored whether individual chronotypes were associated with cardiometabolic risk in patients from the CORDIOPREV study (n = 857). We also investigated whether potential associations were moderated by long-term consumption of two healthy diets (Mediterranean and Low-fat diets). This population was classified into chronotypes using the Morningness-Eveningness Questionnaire. Seven-day daily rhythms in wrist temperature (T), rest-activity (A) and position (P) were recorded in a subset of patients (n = 168), and an integrative variable TAP was determined. Metabolic Syndrome (MetS) was determined at baseline, and metabolic and inflammation markers were measured at baseline and yearly during the 4 years of follow-up. Differences in several lifestyle factors were analyzed according to chronotype. At all times, evening-types had higher triglycerides, C-reactive protein and homocysteine and lower high density lipoprotein cholesterol than morning-types (P < 0.05). Evening-types had a higher prevalence of MetS (OR 1.58 IC 95% [1.10 - 2.28], P = 0.01). Moreover, they were more sedentary, displayed less and delayed physical activity and ate and slept later. In addition, evening-types had lower amplitude, greater fragmentation, lower robustness and less stable circadian pattern at TAP (P < 0.01), all related to a less healthy circadian pattern. In conclusion, evening-types with CVD had higher cardiometabolic risk and less robust circadian-related rhythms than morning-types, regardless of the nutritional intervention.

Circadian timing of eating and BMI among adults in the American Time Use Survey

BACKGROUND/OBJECTIVES

Experimental studies of time-restricted eating suggest that limiting the daily eating window, shifting intake to the biological morning, and avoiding eating close to the biological night may promote metabolic health and prevent weight gain.

SUBJECTS/METHODS

We used the Eating & Health Module of the 2006-2008 and 2014-2016 American Time Use Survey to examine cross-sectional associations of timing of eating in relation to sleep/wake times as a proxy for circadian timing with body mass index (BMI). The analytical sample included 38 302 respondents (18-64 years; BMI 18.5-50.0 kg/m²). A single 24-hour time use diary was used to calculate circadian timing of eating variables: eating window (time between first and last eating activity); morning fast (time between end of sleep and start of eating window); and evening fast (time between end of eating window and start of sleep). Multinomial logistic regression and predictive margins were used to estimate adjusted population prevalences (AP) by BMI categories and changes in prevalences associated with a one-hour change in circadian timing of eating, controlling for sociodemographic and temporal characteristics.

RESULTS

A one-hour increase in eating window was associated with lower adjusted prevalence of obesity (AP = 27.1%, SE = 0.1%). Conversely, a one-hour increase in morning fast (AP = 28.7%, SE = 0.1%) and evening fast (AP = 28.5%, SE = 0.1%) were each associated with higher prevalence of obesity; interactions revealed differing patterns of association by combination of eating window with morning/evening fast (p < 0.0001).

CONCLUSIONS

Contrary to hypotheses, longer eating windows were associated with a lower adjusted prevalence of obesity and longer evening fasts were associated with a higher prevalence of obesity. However, as expected, longer morning fast was associated with a higher adjusted prevalence of obesity. Studies are needed to disentangle the contributions of diet quality/quantity and social desirability bias in the relationship between circadian timing of eating and BMI.