The Circadian Diet – What to Eat and When?

A Question I Get Asked a LOT in Clinic!

Food clock. Healthy food concept

One of the most common questions I get asked by shift workers in our student clinic at Endeavour College of Natural Health in Brisbane is – “What should I eat and when?”

This is a great question given shift workers rarely eat breakfast at “breakfast time”, nor do we necessarily eat dinner at “dinner time”.

I mean “breakfast” for anyone who happens to work 24/7 could be at 4am, or it may not be until midday – depending on your shift.

Given our body is carefully orchestrated by our natural circadian rhythms (the fancy word for our sleep/wake cycles), any variation from these rhythms can play havoc on our body temperature, blood pressure, mental alertness, hormone and neurotransmitter production along with countless other body functions including our gastrointestinal system.

This influence on our gastrointestinal system includes our metabolism, digestion, and absorption of nutrients from the food that we eat.

So in addition to what we eat, along with how much we eat, when we eat is also critical to our overall health and wellbeing.

This was illustrated in an 8-week clinical trial showing how eating mostly carbohydrates at lunch, and mostly protein at dinner, had damaging effects on glucose homeostasis (Alves et al. 2014).  This disruption to our blood glucose regulation can lead to an increased risk in the development of chronic diseases such as diabetes and obesity.

Which brings us to the “Circadian Diet”, or as it’s also referred to as “Chrononutrition”.

Created in 1986 by French nutritionist Dr Alain Delabos, chrononutrition is a term used to describe a way of eating that follows the body’s natural rhythm and enzymatic secretions.

In other words, eating foods at certain times of the day when they can be better utilised by the body.

So let’s begin by discussing one particular macronutrient called, the carbohydrate.

Most of us believe we have to fuel our bodies up in the morning with carbohydrates to give us energy, however this is not actually the case.  When we start our day with a bowl of processed cereal, toast, a bagel (or heaven for bid a donut), we end up feeling fuzzyheaded, exhausted and hungry by midmorning.

Sounding familiar?

In contrast, studies have shown our bodies utilise carbohydrates much more effectively at night-time, as opposed to during the day.

How do they do this?

  • Eating carbohydrates in the evening helps our body maintain the high blood sugar level required for its night-time activities of detoxification, repair and restoration.  Whilst we may think our body slows right down at night, there are certain organs (such as the brain and liver), which are actually hard at work when we’re sleeping.
  • Carbohydrates also help our body to absorb tryptophan and other nutrients needed for sleep, by converting it to serotonin, an important neurotransmitter in the production of our sleepy hormone – melatonin.

Now I’m not suggesting you hold off eating carbohydrates until night-time, as this goes completely against a fundamentally important part of healthy eating, which is to have a diverse array of macronutrient balanced meals comprising of carbohydrates, fats and proteins.

It’s just about shifting the majority of your carbohydrate intake closer to when you’re due for sleep.

For example, eating a generous supply of unrefined carbohydrates which are jam packed with essential vitamins, minerals and fibre before bedtime, as opposed to a massive piece of steak.  These include whole grains, legumes, fruit and lightly cooked vegetables, as these foods are actually going to help you to sleep better as opposed to keeping you awake.

Whilst I’m certainly no fan of diets per se, the Circadian Diet in my mind, is an ingenious way of eating for any sleep-deprived shift worker who has to function on little sleep :-).

 

References:

Alves, R, de Oliveira, F, Hermsdorff, H, Abete, I, Zulet, M, Martinez, J & Bressan, J 2014, ‘Eating carbohydrate mostly at lunch and protein at dinner within a covert hypocaloric diet influences morning glucose homeostasis in overweight/obese men’, European Journal of Nutrition, vol. 53, no. 1, pp. 49-60.

Asher, G & Sassone-Corsi, P 2015, ‘Time for Food: The Intimate Interplay between Nutrition, Metabolism, and the Circadian Clock’, Cell, vol. 161, no. 1, pp. 84-92.

Baker, S 2000, The Circadian Prescription, G.P. Putnam’s Sons, New York.

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