How to eat in sync with your body clock

We’re all so focused on what’s on our plates, but it turns out that when we eat may actually be a more crucial part of the diet puzzle.

In an age of healthier eating habits, time restrictions on our daily food intake can be just as important as what we eat.

It all comes down to a sophisticated 24-hour clock called our circadian rhythm, which regulates our sleep-wake cycle, and every physiological function in our body.

A new form of intermittent fasting aims to work with this process, by restricting our eating window during the day to align with the circadian rhythm, and when our bodies are optimised for functions such as digestion and fat burning.

The results are said to include everything from weight loss to reduced cholesterol levels and lower blood pressure.

So what is the circadian rhythm diet? Here’s what you need to know.

What is the circadian rhythm diet?

The circadian rhythm diet is essentially time-restricted eating in which you eat within a certain time frame, generally during daylight hours, and fast the rest of the time.

Our circadian rhythms are influenced by light and dark, which tells our body when it’s time to wake and when it’s time to sleep.

It is said that nearly every tissue and organ in our body is regulated by a biological clock, with a master clock located in our brain called suprachiasmatic nucleus, or SCN, keeping all the other clocks in sync and on schedule.

There is, however, one interesting thing to note about this system.

“Food actually overrides the clocks in all of our peripheral tissues. It doesn’t affect the brain tissue. The brain keeps going with the sun, but the clocks in the body are actually more controlled by the food that we eat,” says Associate Professor Leonie Heilbronn, who leads the obesity and metabolism laboratory at the South Australian Health and Medical Research Institute.

“Food can unsynchronise the clock in your head from the clocks in your body and when they’re not talking well to each other, you don’t get optimal responses (from the body).”

What are the benefits of the circadian rhythm diet?

In experiments with mice, leading researcher and The Circadian Code author Prof Satchin Panda found those whose calorie intake was not restricted, but whose eating timeframe was restricted to eight to 10 hours, did not become obese or diabetic and had normal liver function and cholesterol levels.

Weight loss as a result of eating in line with circadian rhythms is something Prof Heilbronn also found in research she conducted into time-restricted eating, but other notable health benefits included a reduction in blood pressure and cholesterol levels.

“Eating for a limited amount of time per day gives all the cells in the body time to rest,” Prof Heilbronn says.

“So, your insulin levels come down and your fasting or nutrient signalling pathways come up.

“Also, regulating eating patterns allows your body to anticipate and get to know that it can expect a glucose load at certain times of the day, so it’s prepped and can make the most appropriate responses.”

How to start the circadian rhythm diet

Research into the optimum eating time frame on the circadian diet is still evolving, with windows ranging from four hours to 12 hours being trialled.

But Prof Heilbronn says when it comes to your first meal of the day, generally “the earlier the better”.

Aim to eat about one to two hours from when you get up.

Dietitian Milly Smith advises aiming for early evening as the cut-off time for eating.

Equally as important is what you’re eating, says Milly, of Dietitians Australia.

“If we’re limiting how many meals we’re having during the day, it can start to get really challenging to meet those core food group requirements, which is important in terms of getting all the different nutrients we need daily,” she says.

She suggests eating breakfast, lunch and dinner and incorporating a range of proteins, high-fibre foods and good-quality carbohydrates, which is important for satiety and fuelling the brain.

Additionally, aim to limit your intake of caffeine and alcohol, which are both stimulants.

“What I like about this diet is that it’s sustainable, you can do it for a long period of time,” Prof Heilbronn says.

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Written by Tania Gomez.