Chrono-nutrition is the study of timing and composition of food for maintaining the appropriate functioning of our circadian clock.1 Our circadian clock is our internal timekeeping system which anticipates daily changes and helps maintain homeostasis. As well as our ‘master clock’ located in the hypothalamus which is regulated primarily by light and dark cycles, we have additional peripheral clocks in almost all organs and tissues in the body. Our timing of food and physical activity can influence the timing of these peripheral clocks.

Studies have shown an increased risk of obesity and related health conditions when skipping breakfast and eating late at night. 1 Which suggests the importance of eating a large breakfast and lunch and a smaller meal or snack in the late afternoon or early evening. This will allow the body to digest the food, before sleeping. If the body is still digesting food whilst asleep, energy is taken away from other important roles the body has to complete during rest.

A study on healthy participants found that diet-induced thermogenesis (the amount of energy expenditure of processing food for use and storage) was approximately twice as large in the morning at 8am compared with in the evening at 8pm. Potentially meaning that it takes more calories to digest the same meal in the morning than in the evening.1 Therefore eating late could hinder a weight loss programme.

It is becoming clear that not only what we eat is important, but also when we eat it. Within the body we have natural rhythms for our cortisol levels, they should peak in the early hours of the morning and slowly reduce during the day so that our levels our low in the evening. If this rhythm is misaligned we can have low levels of cortisol as we wake, making us feel lethargic. For some individuals the levels can pick up during the day, leaving us feeling more awake in the evening. Food patterns can be influenced by this misalignment through skipping breakfast and continuing to eat in the late evening. Causing further disruption to our natural circadian rhythm and wellbeing.

Our gut microbiome has its own cyclical changes through the day, to maintain this healthy balance we should ensure we are eating prebiotic foods. Particularly increasing prebiotic foods in your diet in the early part of the day as these will help feed the microbes in your gut, which also have their own cyclical rhythm and influence our overall health.


 1. Garaulet M, Gómez-Abellán P, Alburquerque-Béjar JJ, Lee Y-C, Ordovás JM, Scheer FAJL. Timing of food intake predicts weight loss effectiveness. Int J Obes 2013; 37: 604–11.