When we eat matters. Recent discoveries in chronobiology invite us to review our eating patterns in terms of circadian rhythms, feast and fast [1].

Eating three meals a day with snacks in-between or eating at any time are recent phenomenon in our modern societies [2]. In the scientific community and media, the debate is open between eating regularly versus eating occasionally, between grazing and intermittent fasting. Chrononutrition, the synchronisation of food intake with our natural circadian rhythms [3], is an innovative approach to optimal nutrition and healthy longevity.

In Chinese Medicine, the rhythm of different organs and their desynchronisation from daylight and seasonal influences has always been perceived as a root cause of chronic disease. Besides, many cultures and religions practice seasonal and rhythmic rituals (like Lent, Ramadan or Vinaya).

These traditional perspectives have recently been validated by modern science, revealing the molecular mechanisms that control the body’s circadian rhythms.

All biological processes follow an approximate 24-hour cycle – called the circadian rhythm – regulated by a central clock located in the hypothalamus. This central clock is known to respond to external signals such as day and night. However, it’s only recently that researchers have discovered that this central clock also synchronises with multiple peripheral clocks located in our main organs.

These ‘inner timekeepers’ are not affected by light but are influenced by our body temperature and feeding/fasting rhythms [4, 9]. They affect physiological processes such as glucose and lipid metabolism in a feedback mechanism.

• Desynchronisation with natural light and dark cycles, such as poor sleep, jet lag or shift work stimulates hunger and increase food intake. This affects fat storage [5]. These modern disruptions also disturb the natural oscillation of our gut microbiome. The good news is that once natural circadian rhythms are restored, the risk of chronic disease related to these metabolic changes decreases.
• Meal schedule itself acts as a circadian cue. Insulin secretion, all calories equal, varies based on meal time [6]. More than 80% of the liver “clocks” respond to timing and frequency of food intake [4]. Specific eating schedules have an impact on the gut microbiome circadian rhythms [7, 11]. Up to 80% of our genes show a rhythmical response to eating [8]. Therefore, eating schedules affect weight, blood sugar balance and cortisol levels [2].
• Both meal timing and meal frequency determine our peripheral clocks oscillations [3, 4]. While exploring the liver’s daily cycles, S. Gill and S. Panda found that reducing the “eating windows” of participants over 16 weeks contributed to an increased sense of wellbeing for a year [10].

Modern lifestyle perturbs the human circadian system, primarily with shift work, exposure to prolonged hours of artificial light and erratic eating patterns [2]. The “chrono-disruption” of our natural feeding/fasting rhythms contributes to the disturbance of our hormonal and neural balance and alter our food assimilation. The resulting metabolic changes increase our risk of chronic disease, from diabetes to cancer.

More recent studies in Time-Restricted Feeding (TRF) show that clearly identified fasting/feeding cycles consolidate the circadian rhythm of gene expression. Scheduled meals and periodic fasting can re-align the natural circadian rhythms of peripheral clocks, improving food metabolism and sleep [11, 12]

These positive metabolic results improve with a good breakfast and late lunch or an early lunch and early dinner, as long as the “fasting window” is maintained over 14 to 16 hours. These effects of TRF involve the biological process of “hormesis”, which is the adaptive cellular response to mild stress.

Is there an optimal time to eat for healthy longevity?

If food quantity and quality has been primarily discussed and is still the foundations of good health, it is now time to consider meal timing and meal frequency as a key for optimal nutrition.

Whatever your chronotype [13], research shows that TRF positively affects the circadian rhythms of peripheral tissue, while erratic feeding patterns disturb these clocks.

In short, disturbed circadian rhythms alter digestion, affect sleep and prevent the management of healthy weight. The backbones of chrononutrition for healthy longevity rely on:

• Routine – Regular eating patterns
• Rest – Prolonged digestive rest by increasing our fasting window
• Reset – Eating during daylight

When you shift your focus from WHAT to WHEN you eat, you will immediately begin feeling more energised. You may well live longer and healthier. This is the purpose of chrononutrition.

If you don’t know where to start, refer to a qualified nutritionist listed on atms.com.au

References

[1] Paulose JK, Cassone CV, Cassone VM (2019) “Aging, melatonin biosynthesis, and circadian clockworks in the gastrointestinal system of the laboratory mouse”, Physiol Genomics. 2019 Jan 1;51(1):1-9.doi: 10.1152/physiolgenomics.00095.2018.

[2] Mattson MP & al (2014) “Meal frequency and timing in health and disease”, Proc Natl Acad Sci U S A. 2014 Nov 25; 111(47): 16647–16653. doi: 10.1073/pnas.1413965111

[3] Oike H,  Oishi, K,  & Kobori, M (2014) “Nutrients, Clock Genes, and Chrononutrition”,  Curr Nutr Rep. 2014; 3(3): 204–212. doi: 10.1007/s13668-014-0082-6

[4] Gnocchi D, Bruscalupi G (2017) “Circadian Rhythms and Hormonal Homeostasis: pathophysiological Implications”, Biology 2017, 6, 10; doi:10.3390/biology6010010

[5] Hanlon EC (2016) “Sleep Restriction Enhances the Daily Rhythm of Circulating Levels of Endocannabinoid 2-Arachidonoylglycerol”, Sleep, Volume 39, Issue 3, 1 March 2016, Pages 653–664, doi.org/10.5665/sleep.5546

[6] Jakubowicz D & al (2013) “High caloric intake at breakfast vs. dinner differentially influences weight loss of overweight and obese women, Obesity (Silver Spring). 2013 Dec;21(12):2504-12. doi: 10.1002/oby.20460. Epub 2013 Jul 2.

[7] Deaver JA, Eum SY,& Toborek M (2018) “Circadian Disruption Changes Gut Microbiome Taxa and Functional Gene Composition”, Front Microbiol. 2018; 9: 737. doi: 10.3389/fmicb.2018.00737

[8] Mure LS & al (2018) “Diurnal transcriptome atlas of a primate across major neural and peripheral tissues”, Science  16 Mar 2018; Vol. 359, Issue 6381, doi: 10.1126/science.aao0318

[9] Andreani TS & al (2015) “Genetics of Circadian Rhythms”, Sleep Med Clin. 2015 Dec; 10(4): 413–421. doi: 10.1016/j.jsmc.2015.08.007

[10] Gill S and Panda S (2016) “A smartphone app reveals erratic diurnal eating patterns in humans that can be modulated for health benefits”, Cell Metab. 2015 Nov 3; 22(5): 789–798. doi: 10.1016/j.cmet.2015.09.005

[11] Asher G & Sassone-Corsi P (2015) “Time for Food: The Intimate Interplay between Nutrition, Metabolism, and the Circadian Clock”, Cell Press – Volume 161, Issue 1, 26 March 2015, Pages 84-92

Review. https://doi.org/10.1016/j.cell.2015.03.015

[12] Longo VD  & Panda S (2016) “Fasting, circadian rhythms, and time restricted feeding in healthy lifespan”, Cell Metab. 2016 Jun 14; 23(6): 1048–1059. doi: 10.1016/j.cmet.2016.06.001

[13] Figueiro MG, Plitnick B & Rea M (2014) “The effects of chronotype, sleep schedule and light/dark pattern exposures on circadian phase”, Sleep Med. 2014 Dec;15(12):1554-64. doi: 10.1016/j.sleep.2014.07.009. Epub 2014 Sep 3.