Anmore Health and Wellness
3025 Anmore Creek Way V3H5G6 Port Moody, BC, Canada

Wow! The most comprehensive study compilation on meal timing, fasting, circadian rhythms, hormones, the gut microbiome, cardiovascular disease, obesity risk an...d more. I’ve been waiting for a while for some of this data to finally come out and debunk some potentially harmful fads, like breakfast skipping, which never made sense to me from both a scientific hormonal perspective, and also from a traditional/cultural eating perspective. Chinese medicine pretty much had this down a couple thousand years ago, and so did your grandmother! Science is now just beginning to explain why they were right. Read the full text here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6520689/ (Thank you Dr. Robert Silverman for the reference!) These findings underline that not only the food quality but also frequency and timing are crucial for optimal health. In general, available data suggest that if there are health-promoting effects of reducing meal frequency, there may be differential effects of skipping breakfast versus dinner (i.e., evening fasting before an overnight fast vs. an overnight fast followed by continued morning fasting). Moreover, it has been suggested that late eating is related to increased risk of obesity and CHD [59] and also that a grazing eating pattern is related to higher total energy intake and later night-time food consumption [60]. Finally, there is a consensus about the association between breakfast consumption and CHD. Cahill et al. [18] published a large prospective study from the Health Professionals Follow-up Study on 26,902 American men aged 45 to 82 years. They found that men who skipped breakfast had a 27% higher risk of CHD compared with men who regularly ate breakfast (RR 1.27; 95% confidence interval CI 1.061.53). Additionally, eating late at night led to a 55% higher CHD risk (RR 1.55; 95% CI 1.052.29) compared to an earlier dinner. On the contrary, regarding cardiovascular health, Uzhova and collaborators found that skipping breakfast was associated with an increased risk of non-coronary and generalized atherosclerosis independent of conventional CVD risk factors in a sample of middle-aged asymptomatic individuals [63] Also different physiological functions exhibit circadian rhythm: for example glucose tolerance changes during the day showing a poorer glycaemic control in the evening and at night in healthy adults. These changes are influenced by diurnal rhythms in -cell responsiveness, insulin clearance, and peripheral insulin sensitivity, whilst hepatic insulin sensitivity seems to be less important. However, the circadian rhythm and the inner clock mechanism could be affected by different factors such as light exposure, sleep/wake, physical activity, and food intake. Actually, meal timing is one of the main factors that might influence these physiological functions and, therefore, various health outcomes and body weight control [76]. Meal timing influences either the central master clock (SCN) or peripheral cellular clocks, including Bmal1, Clock, Per1/2, Cry1/2, Rev-erb/, Ror/, Dbp, Dec1/2, CK1/, and NPAS2 [74,77]. It is important to underline that peripheral tissues show proper circadian rhythms and cellular clocks. Central and peripheral clocks work together and they are also influenced by food availability. Indeed, regular feeding patterns may synchronize human peripheral clocks and delayed meals could instead influence plasma glucose rhythm but not insulin rhythm [78]. If the potential health-promoting effects of less frequent eating are considered sufficient for implementation of this dietary strategy, is consuming one daily meal equivalent to the consumption of two daily meals? In this case, the answer is not merely less is better: reducing food intake to only one meal per day may worsen the positive effect of lower meal frequency [87,88]. Therefore, the intake of two (or three) meals per day is perhaps the best option, and the difference between two or three could depend on the length of the daily fasting period they produce. This desynchronization of internal clocks, and thus the modification of microbiota, is associated with increased risks of metabolic and cardiovascular diseases. Recently it has been demonstrated that a chronic circadian misalignment in mice and a time shift jetlag in humans induces a dysbiosis; this dysbiosis has been demonstrated to be able to promotes glucose intolerance and obesity in a germ-free mice throughfaecal transplantation [117]. On the other hand, maintaining a correct eating phase (diurnal for humans) and increasing the fasting period (i.e., reducing meal frequency) could positively affect the gut microbiome, reducing gut permeability and improving systemic inflammation. Based on the evidence presented in this review, several interesting health-promoting recommendations can be shared with the audience. There may be physiological benefits to consuming a greater proportion of calories earlier in the day, which often involves breakfast consumption, as compared to consuming a large number of calories later at night. There may also be benefits to extending the daily fasting period beyond a standard overnight fast or implementing occasional fasting periods. In order to reconcile these two strategies, an individual could eat from breakfast until mid- to late-afternoon each day (Figure 3). However, it should be considered that this style of eating may not be desirable or feasible for many individuals, as it represents a paradigm shift from traditional eating patterns in many parts of the world. It is well-known that disruption of central and or peripheral circadian clocks could promote obesity and CHD in many organisms [72]. Almost all species have developed an internal cellular clock mechanism, sensitive to the light and dark phases of a day, which allows animals to anticipate and to adapt to the changes in the environmental conditions linked to light and darkness. Early research performed in the 1970s identified the suprachiasmatic nucleus (SCN) as the main biological clock. The SCN regulates not only sleep-wake cycles but also many other physiological variables such as body temperature, blood pressure, hormone secretion, and behavioural variables. These circadian rhythms allow the organism to adapt to the environment and to be prepared for the different demands of daily life. For example, the morning increase of cortisol prepares the cardiovascular system for the upcoming day’s activities, and thus disruption of the circadian cortisol rhythm and the consequent cardiovascular impairment could lead to an increased risk of cardiovascular events in the early morning [73]. Another important marker of the internal clock is melatonin. Melatonin is strongly regulated by light/dark cycle with high levels during the night in all vertebrates. This fundamental rhythmic endocrine signal for darkness in the body is controlled by the master clock in the SCN and mainly by the Period gene (Per1) that has been shown to cycle rhythmically in the pineal gland [74]. For instance, McHill et al. [75] found that, on average, obese individuals consumed most of their calories an hour closer to melatonin onset (biological marker of impending sleep onset) compared to lean individuals.