How to improve your metabolism, digestion and sleep? The circadian rhythm diet.

2 February 2022

by Émilie Rouvroy

When it comes to having a healthy diet, we all know what foods we should be eating. But did you know that when you eat, and how often, is just as important as what’s on your plate? It’s all down to your circadian rhythm, your body’s internal body clock.

Influencing everything from your sleep cycle to your metabolism, your circadian rhythm plays a big role in many physiological processes. And it affects more of your day to day life than you may realise! If you’re struggling to lose weight despite dieting, or if you just can’t sleep at night, a disrupted circadian rhythm may be to blame.

So here’s everything you need to know about the circadian rhythm and eating, and how to improve your overall health by keeping it on track.

What is a circadian rhythm?

A circadian rhythm is an internal, 24-hour body clock that affects your sleep, digestion, and metabolism (1). Running non-stop in the background, it’s a natural process that not only tells the body’s different systems to function, but when. It influences many biological processes, including:

  • Hormone release
  • The sleep/ wake cycle
  • Body temperature
  • Digestion
  • Metabolism
  • Eating habits

What controls the circadian rhythm?

Our circadian rhythms are influenced by two main environmental factors; light and the timing of our meals. In the evening, in response to darkness, the body produces melatonin. This hormone prepares the body for sleep – essentially a period to rest and heal. By contrast, in response to daylight, the body stops producing melatonin but produces and releases insulin, which makes us feel awake. Not only does it make us feel energized, but it signals to our body that it’s time to start metabolising carbohydrates and transporting glucose to the cells that need it.

Our eating habits also play a major role in how well our body clock is synchronised. Recent studies have shown that the timing and frequency of eating can affect how well your circadian rhythm functions. (2). This is also down to the hormone insulin. Researchers at Manchester University state that “ insulin, released when we eat, can act as a timing signal to cells throughout our body.” (3). If we eat at irregulat times – such as late at night – this can stimulate the body to produce insulin when we should be resting, and reduces how well our metabolism functions.

What happens when the circadian rhythm is interrupted?

As our circadian rhythm controls so many of our body’s complex and intertwined biological processes, interrupting them can have far reaching consequences. Studies are showing more and more that a disrupted circadian rhythm can lead to sleep disorders like insomnia (4), and possibly increase the risk of developing metabolic diseases such as obesity, diabetes and cardiovascular disease (5). As metabolism has also been shown to play a significant role in maintaining (or losing) weight (6), a disrupted rhythm may also make it harder to lose weight despite eating a healthy diet.

In our modern, fast-paced culture, there are so many things that can disrupt your body’s natural rhythms. You may not even realise that these can have an affect on your sleep quality, weight and overall health, but the following eating and sleeping habits can easily interfere with your body clock (7):

  • Frequent jet lag
  • Working night shifts
  • Late-night clubbing
  • Light from electronic devices before bed
  • Eating late at night
  • Skipping breakfast

How to eat in harmony with your circadian rhythm

Synchronizing your biological clock with your food intake is also known as the circadian rhythm diet or the body clock diet. However, it’s more a lifestyle than a diet as such.  So, how does it work? To keep your circadian rhythm on track, try to follow these simple steps:

  • Consistency is key: try to establish a routine and regular eating pattern and stick with it
  • Eat your food within a maximum 12-hour window
  • Eat the majority of calories in the first part of the day (breakfast around 8am, and lunch at around 1pm)
  • Avoid food intake close to bedtime, or very early morning when melatonin levels are high. Ideally, have a light dinner no later than 7pm

This being said, as each of us has slightly different lifestyles, it’s hard to pinpoint an exact circadian rhythm eating window that would be perfect for everyone. But you can follow these as a general rule, and find your own circadian rhythm eating times that work with your body’s clock!

Work with me if you’d like to to explore what lifestyle, health or diet factors may be disrupting your circadian rhythm, and improve your overall health and wellbeing.

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