The importance of the circadian rhythm in regulating human food intake behaviour and metabolism has long been recognised. However, little is known as to how energy intake is distributed over the day in existing populations, and its potential association with obesity. The present review describes global trends in time-of-day of energy intake in the general population based on data from cross-sectional surveys and longitudinal cohorts. Evidence of the association between time-of-day of energy intake and obesity is also summarised. Overall, there were a limited number of cross-sectional surveys and longitudinal cohorts that provided data on time-of-day of energy intake. In the identified studies, a wide variation in time-of-day of energy intake was observed, with patterns of energy distribution varying greatly by country and geographical area. In relation to obesity, eight cross-sectional surveys and two longitudinal cohorts were identified. The association between time-of-day of energy intake and obesity varied widely, with several studies reporting a positive link between evening energy intake and obesity. In conclusion, the current review summarises global trends in time-of-day of energy intake. The large variations across countries and global regions could have important implications to health, emphasising the need to understand the socio-environmental factors guiding such differences in eating patterns. Evidence of the association between time-of-day of energy intake and BMI also varied. Further larger scale collaborations between various countries and regions are needed to sum data from existing surveys and cohorts, and guide our understanding of the role of chrono-nutrition in health.

The association between excess cortisol and various parameters of metabolic syndrome including hypertension, insulin resistance and dyslipidaemia is increasingly recognised. The present single-blind randomised placebo-controlled cross-over study compared the effect of polyphenol-rich dark chocolate (DC) on biomarkers of glucose metabolism, lipid profile, and blood pressure (BP) in females with BMI ≥ 25 kg m⁻² (n = 21) and females with BMI < 25 kg m⁻² (n = 21). Volunteers consumed 20 g of DC containing 500 mg polyphenols or a placebo DC with negligible polyphenol-content daily for 4 weeks, separated by a 2-week washout period. Systolic BP and diastolic BP decreased after 4 weeks of polyphenol-rich DC. Placebo raised fasting insulin, homeostasis model assessment of insulin resistance (HOMA-IR) and salivary cortisol, an effect that was significantly different from polyphenol-rich DC which had a negligible effect on fasting insulin, HOMA-IR and salivary cortisol. Females with BMI ≥ 25 kg m⁻² responded less favourably to placebo than lean females and consequently had higher fasting insulin and HOMA-IR, in addition to a lower quantitative sensitivity check index (QUICKI) after ingestion of placebo compared to polyphenol-rich DC. No significant changes in lipid profile were observed. This study provides evidence for the metabolic benefits of consuming polyphenol-rich dark chocolate while demonstrating the possibility of adverse effects occurring with polyphenol-poor chocolate placebo.

Background: Objective: Methods: Results: Conclusions:

Associations between timing of eating occasions and their nutrient composition and health have been described in interventional and cross-sectional studies. However, data from longitudinal data are limited. This study examined 17-year changes in energy and macronutrient intake across eating occasions in the 1946 British birth cohort. Data were obtained from the 1946 British birth cohort. Cohort members completed 5d-estimated diaries at ages 36 (1982), 43 (1989) and 53 years (1999). Data from subjects who provided dietary data at all three time points were analysed (n=1253). Repeated-measures analysis of variance with post hoc Bonferroni's adjustment was used to examine changes in energy and macronutrient at breakfast, mid-morning, lunch, mid-afternoon, evening and extra meal slots between 1982 and 1999. Analyses were stratified by sex and social class. The proportion of energy and macronutrients consumed at lunch declined between 1982 and 1999, which was compensated by a greater intake in the mid-afternoon and evening. This trend was seen across sex and social class, although women and adults with a non-manual occupation reported greater energy, carbohydrate and non-starch polysaccharide intake at breakfast in 1982 and had a higher protein intake in the evening compared with men and adults with a manual occupation. The timing of energy and nutrient intake has shifted slightly over time, with a greater proportion of intake later in the day. The association between the observed sex and occupational social class differences in eating profiles and chronic disease warrants investigation.

Limited observational studies have described the relationship between sleep duration and overall diet. The present study investigated the association between sleep duration on weekdays or social jetlag and empirically derived dietary patterns in a nationally representative sample of UK adults, aged 19–64 years old, participating in the 2008–2012 UK National Diet and Nutrition Survey Rolling Programme. Survey members completed between three to four days of dietary records. Sleep duration on weekdays was categorized into tertiles to reflect short, normal, and long sleep duration. Social jetlag was calculated as the difference between sleep duration on weekends and weekdays. The association between sleep duration/social jetlag and dietary patterns, derived by principal components analysis, was assessed by regressing diet on sleep, whilst accounting for the complex survey design and adjusting for relevant confounders. Survey members in the highest tertile of sleep duration had on average a 0.45 (95% Confidence Interval (CI) −0.78, −0.12) lower healthy dietary pattern score, compared to middle tertile (p = 0.007). There was an inverted u-shaped association between social jetlag and the healthy dietary pattern, such that when sleep on weekends exceeded weekday sleep by 1 h 45 min, scores for indicating a healthy dietary pattern declined (p = 0.005). In conclusion, long sleep duration on weekdays and an increased social jetlag are associated with a lower healthy dietary pattern score. Further research is required to address factors influencing dietary patterns in long sleepers.

Objectives: The role of circadian rhythm of energy and macronutrient intake in influencing cardiometabolic risk factors is increasingly recognized. However, little is known of the association between time of energy intake and blood pressure. We examined the association between time-of-day of energy intake and subsequent hypertension and change in blood pressure. Methods: The analysis included 517 men and 635 women from the 1946 British birth cohort. Diet was assessed using 5-day estimated diaries. Diaries were divided into seven meal slots: breakfast, mid-morning, lunch, mid-afternoon, dinner, late evening and extras. Time-of-day of energy intake at age 43 years was related to hypertension prevalence at 43 years and incidence at age 53 years and 10-year changes in SBP and DBP using logistic regression and censored regression controlling for medication use. Results: Cohort members in the highest quintile of energy intake at breakfast at age 43 years had 30% lower odds of hypertension prevalence compared with those in the lowest. Cohort members in the highest quintile of energy intake at late evening had higher odds of incident hypertension at age 53 years [odds ratio = 1.55; 95% confidence interval (CI) 0.93–2.61; P for linear trend = 0.052]. Compared to the lowest quintile, the highest quintile of energy intake late in the evening was related to a greater rise in SBP (β = 5.09; 95% CI 1.25–8.93) and DBP (43–53 years) (β = 2.08; 95%CI 0.27–5.32). Conclusion: Higher energy intake at breakfast is associated with lower hypertension prevalence. Greater energy intake late in the evening is associated with higher hypertension prevalence, incidence and greater increases in blood pressure.