Every day, it seems there is never enough time to do what we need or want to do. But clocks, calendars, and schedules are not human inventions. They are an integral part of life from the simplest one-celled organisms all the way to human beings.

Last October, the Nobel Prize in Physiology or Medicine award went to J.C.Hall, M.Rosbash and M.W.Young for their discoveries about the molecular mechanisms controlling the body’s circadian rhythm. This official scientific acknowledgement of biological rhythms as  a key factor for health and wellness is a real opportunity to talk about chrononutrition.

Chronos is the personification of time in Greek mythology. Chronobiology is the study of how biological clocks work to control and regulate almost every function of life. And chrononutrition is about the synchronisation of food administration and natural body rhythms for optimum absorption:

Natural rhythms were an integral part of Ancient traditional medicine’s protocols :Traditional Chinese Medicine already believed what science has just validated: that each organ possesses its own rhythms.

Our central clock in the suprachiasmic nucleaus (SCN), located in the hypothalamus merely governs activity-related rhythms such as sleep/wake cycles, core body temperature, neurotransmitter and hormone secretion. As early as the 80’s research shows that our internal clock, known to function on external cues (called zeitgebers), was in fact more complex and synchronized with multiple peripheral clocks located in our organs. Recent studies show precisely how these peripheral clocks impact some physiological processes such as glucose and lipid metabolism in a feedback mechanism. Our brain talks to and at the same time listen to our cells.

Disruption of our natural body rhythms contribute to modern chronic disease such as metabolic syndrome, obesity, cardiovascular disease or even cancer.

Body clocks impact food intake, food choices and food absorption

Altered circadian rhythms, such as sleep restriction, induce chemical changes in the body that result in increased food intake and fat storage. With jet lag and shift work, these metabolic changes have been shown to induce increased risks of cardiovascular diseases. The good news is that once natural rhythms are restored, the risk factors decrease.

Meal timing impact food intake, food choices and food absorption 

Feeding acts as a circadian rhythm. The timing of our meals impact our weight, blood sugar balance, and cortisol levels: in many studies, late eaters have been shown to get more difficulty to lose weight, eat more during the day while burning less calories, and present with higher blood sugar imbalances and cortisol levels.

The balance between the amount of food and the interval between feeding periods determine the liver clock rhythmicity: eating late disrupt the natural nocturnal fasting period and in turn affects  the liver clocks. This chrono disruption leads to sub-optimal fat and carbohydrate assimilation.

Unusual food timing contributes to overeating as the desynchronization of natural circadian rhythms lowers levels of circulating letpin, the hormone that helps suppress hunger.

Melatonin, commonly known as a sleep hormone, is found in the digestive tract where it influences hunger and satiety and affects the peristaltic movement of the intestines.

Digestive hormones, such as ghrelin and cholecystokinin, also require a circadian rhythm to function properly. Research starts to understand as well how the eating patterns shape the rhythmicity and composition of the gut microbiome (the trillions of bacteria working in synergy in the intestines).