Should I try the 'Circadian Diet'?

Why breakfast might be the most important meal of the day after all!

‘Breakfast is the most important meal of the day’ – we’ve all heard this saying countless times, but until recently, there hasn’t been much research to support the benefits of eating early in the day.

On the contrary, intermittent fasting has become increasingly popular, with many people choosing to skip breakfast all together in hopes of restricting calories, losing weight, or improving their health.

In both scenarios, it’s clear that it’s not just what we eat and how much that matters, but the timing of when we eat too. This type of research has a name too – chrono nutrition is a relatively new field of research that studies the timing of our food in relation to our health. So, what does the science say? An emerging topic is that of ‘Circadian eating’, which is a pattern of eating that may have significant implications for our health!

What is circadian eating?

We all have a natural internal 24-hour clock, called our circadian rhythm, which regulates our sleep as well as other body functions like our immunity, metabolism, and digestion. Circadian eating is a pattern of eating that follows this biological clock, and keeps our intake of food within the 10-12 hour ‘wake’ cycle. It also involves spreading our intake of food throughout the day so that our heavier meals are in the morning and our lightest meal at night.

What’s the difference between circadian eating and intermittent fasting?

While there are different types of intermittent fasting (IF), IF focuses on periods of restricted eating and often involves fasting in the morning. Circadian eating, on the other hand, still involves a confined period of eating, but it focuses more on having an earlier intake of food and emphasises reducing eating late in the day.

What does the evidence say about circadian eating?

• May lead to weight loss

A systematic review (published by one of our dietitians here at the Gut Health Dietitian!) found that focusing on eating earlier on in the day can lead to greater short-term weight loss than eating later on in the day (1).

• May impact fat metabolism and hunger hormones

A recent study looked at the effects of eating late in comparison to eating early. This study found that eating late increased hunger, impacted appetite hormones, and affected fat metabolism in a way that more energy was stored as fat (2)!

• May increase longevity

There is some research to support that eating in alignment with your circadian rhythm can increase longevity. In fact, one study found that mice following this pattern of eating lived 35% longer (3)!

• May reduce risk of metabolic diseases

In studies done on shift workers, it has been found that eating meals at ‘irregular’ times may increase the risk of developing type 2 diabetes, cardiovascular diseases, and obesity (4). On the other hand, time restricted eating that Is restricted to the day time may improve markers of these diseases (4).

• May improve sleep quality

Another reason why it may be a good idea to avoid eating late in the evening is that it may impair sleep quality and increase the risk of reflux (5).

• May improve gut health

The gut has a sleep-wake cycle of its own. Eating large amounts of food late in the evening can disturb this cycle in a way that the gut can’t “sweep” out any substances that don’t belong there. See our blog on the Migrating Motor Complex for more on this.

How can you eat according to your circadian rhythm?

‘Front-loading’ your day by having a balanced and nourishing breakfast is a great place to start! Planning so that you have a proper lunch for yourself (rather than a few scrapings of leftovers) can also help. Eating regularly and eating earlier on may also help to prevent cravings later in the day, reduce your portion size at dinner, and prevent late night snacking.

The Takeaway

Emerging research is showing us that our pattern of eating across the day can impact our health. Eating according to our circadian rhythm, eating our larger meals earlier on in the day, and reducing the amount we eat later in the day may help to improve markers of health!

References

[1]      Young IE, Poobalan A, Steinbeck K, O’Connor HT, Parker HM. Distribution of energy intake across the day and weight loss: A systematic review and meta-analysis. Obes Rev 2023. https://doi.org/10.1111/obr.13537.

[2]      Vujović N, Piron MJ, Qian J, Chellappa SL, Nedeltcheva A, Barr D, et al. Late isocaloric eating increases hunger, decreases energy expenditure, and modifies metabolic pathways in adults with overweight and obesity. Cell Metab 2022. https://doi.org/10.1016/j.cmet.2022.09.007.

[3]      Acosta-Rodríguez V, Rijo-Ferreira F, Izumo M, Xu P, Wight-Carter M, Green CB, et al. Circadian alignment of early onset caloric restriction promotes longevity in male C57BL/6J mice. Science (80- ) 2022. https://doi.org/10.1126/science.abk0297.

[4]      Schuppelius B, Peters B, Ottawa A, Pivovarova-Ramich O. Time Restricted Eating: A Dietary Strategy to Prevent and Treat Metabolic Disturbances. Front Endocrinol (Lausanne) 2021. https://doi.org/10.3389/fendo.2021.683140.

[5]      Newberry C, Lynch K. The role of diet in the development and management of gastroesophageal reflux disease: Why we feel the burn. J Thorac Dis 2019. https://doi.org/10.21037/jtd.2019.06.42.

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