Healthy food

Why food timing matters5 minute read

Healthy food

Modern life makes it easy to forget we’re rhythmic beings. Electricity means we can heat and eat food whenever we want. Air travel means we can escape winter for hotter climes. Hell, even Netflix can mean we stay up for most of the night.

And yet, our rhythms are also inescapable. Most people need to sleep during every 24-hour period. Women have periods every month. Research has also shown that our gut bacteria undergo daily fluctuations [1].

These rhythms are controlled by a network of ‘clocks’ in our body. The master clock is found in the brain, and it uses the light pouring in through our eyes to synchronise itself with the outside world [2]. There are lots of other clocks around the body, which are known as ‘peripheral’ clocks.

From appetite to body temperature, together the master clock and peripheral clocks control a host of bodily functions throughout the day and night [3].


Keeping in time

But here’s the really interesting part: our behaviour can also help to set the rhythm in our peripheral clocks. In other words, it goes both ways.

While the master clock is largely under its own control, our sleeping habits, our lifestyle and even the food we eat can influence the tick-tock of the clocks in other organs.

But why does this matter? Well, new research is beginning to show that to achieve optimal health, we need to make sure all our clocks are in sync [4].

It’s possible to picture this as a sort of orchestra. The master clock acts as a conductor, making sure everyone else is in time. If someone is distracted and misses the beat, the music can sound a bit messy.

Our bodily function is no different. For smooth physiological processes, we want to keep everything in time.


Missing the beat

‘Chronodisruption’ is the opposite of everything being in time—and it’s surprisingly common. Jet lag is the most obvious example, but shift work and ‘social jet leg’ (where our lifestyles are out of sync with are bodily rhythms) can throw things off too.

In fact, studies suggest that people who consistently live outside the normal light-dark/sleep-wake/feast-fast pattern of life are more likely to develop conditions such as obesity, metabolic syndrome and high blood pressure [5].

So, what can we do?


How to make chrono-nutrition work for you

The circadian rhythm refers to the cycle of bodily processes that occur roughly every 24 hours. It is one of the key rhythms governed by your clocks.

‘Chronotherapy’ is the use of certain practices and behaviours to support this rhythm. ‘Chrono-nutrition’ is an offshoot of this—and it simply means timing our food intake to promote optimal health.

Research in this area is quickly gathering pace, and we’ve made some interesting discoveries already. For those wishing to optimise their circadian rhythm, here’s where to start:


1) Eat breakfast

This isn’t a new idea, but one that’s been re-confirmed by chrono-nutrition research. Studies show that eating breakfast helps your peripheral clocks sync with your master clock [6].

Much like the light that resets your master clock, it’s likely that the first meal of the day lets the clocks in your digestive system (and other organs) know that…well…the day has begun.

Interestingly, studies also show that eating breakfast can help to satisfy your appetite for the rest of the day. What’s more, those who don’t eat breakfast tend to eat more carbohydrates later on.


2) Drink coffee in the morning

Caffeine is a powerful stimulant and can have a dramatic effect on our body’s processes. In fact, a double espresso can delay your normal circadian rhythm by 40 minutes—which is comparable to the effect of bright light [7].

This means it’s best to avoid drinking coffee in the evening, but it could be a good idea to drink it first thing in the morning if you’re suffering from jet lag. A strong coffee (especially if accompanied by natural light first thing) could help your body’s clocks realign themselves to their new location.


Cup of coffee


3) Fast for 12 hours every day

In the past, our ancestors would have stopped eating when it became dark. Artificial light changed all this—so much so that most people graze for up to 16 of the 24 hours in a day.

The problem with constant eating is that it doesn’t give the digestive system time to rest and repair. Our bodies are hardwired to associate food with daylight hours, so it can also confuse our internal clocks.

Studies show that eating during a set period can help to reset circadian rhythm [8]. But you needn’t be too strict—consuming all your food within a 12-hour period is a good place to start.

In practice, this means eating your first bite of breakfast at 8am, and eating your last bite of dinner by 8pm. This time-restricted feeding has the added benefits of improving sleep and increasing alertness [9].


4) Eat a light dinner

Again, this isn’t a revolutionary recommendation. Believe it or not, the adage ‘Eat like a king in the morning, a prince at noon, and a peasant at dinner’ was first expressed by a philosopher and doctor in the 12th century [10].

And yet few people heed this advice. In fact, English people typically consume 40% of their daily calories at dinner [11].

Our circadian rhythm mean that our bodies are actually more efficient at using calories during the day. Studies appear to back this this up: people who have bigger breakfasts and smaller evening meals tend to lose more weight [12].

Since our digestive processes tend to slow down during the evening, it can be easier on your body to eat the majority of your calories during the day. Slow-cooked and soft foods, such as soups and stews, can be a good choice for your final meal of the day—as the cooking or blending takes some of the burden off the digestive system.


As research develops, we’ll no doubt learn more about the importance of food timing. It’s fascinating that modern science can shine light on biological mechanisms, but perhaps we should be paying more attention to the practices—eat breakfast, don’t eat late at night—that have been cultivated by generations of intuition.

The natural world is governed by rhythms that are as old as time, and it appears our bodies are no different.


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Dr Thivi Maruthappu


Dr Thivi Maruthappu is the UK’s first and only dual-qualified Consultant Dermatologist and Nutritionist, and the pioneer of the (much-needed!) Nutritional Dermatology field. She runs busy NHS dermatology clinics, conducts academic research and delivers lectures worldwide. She’s also recently authored her first book, Skin Food, which aims to make holistic skincare accessible for everyone.



Porter magazine called her a ‘Global Skincare Expert’, and Caroline Hirons described her as ‘one of the best facialists in the world’. In the skincare industry, Marie Reynolds is in a league of her own. I had the privilege of experiencing one of Marie’s facials as a young journalist—and I can still remember every exquisite detail more than a decade later.

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