Circadian Rhythms, Part 2: Riding the Circadian Wave to Support Healthy Food Intake

best time to eat

In our last blog post, we made a general introduction to the concept of circadian rhythm (CR) and its importance in maintaining balance in our daily routines and sleep. In this blogpost, we’re going to take a little closer look at one particular aspect of the impact of CR: supporting the maintenance of healthier food intake and more efficient weight control.

One of the most important connections between CR and your weight is the impact CR has on the release of hormones in your body. In fact, a host of hormones have a “pulsed release” throughout the day and night; the timing of those pulses is shaped in large part by CR.

An important driver of metabolism is the hormone cortisol. Our metabolism can be understood as the process by which the body breaks down food and turns it into energy. This isn’t just what happens in your stomach, but it refers to a wide range of biochemical processes within an organism. So, something that impacts your metabolism has a huge influence on your overall health and well-being. CR’s connection to your metabolism is that it helps trigger a cortisol rise in the morning. Cortisol is your “get up and go” hormone; it drives your metabolism, supports  thyroid function, and contributes to the energy you can access to complete your daily activities. Because your metabolic processes are receiving a bit of a jump start from cortisol, the food you consume during that time has a greater likelihood to be burned and turned into fuel rather than stored as fat. In short, the number of calories your body retains (rather than burns off) is not only affected by how much you eat but also by when you eat.

Your CR supports a diurnal (or daily) release of cortisol. This means that two times per day your cortisol level peaks: once in the early morning and another time in the late morning. After that, this hormone should slowly decline so it reaches a low point in the evening. Knowing that cortisol levels peak not once but twice in a relatively small fraction of the entire day, it seems that a piece of dry toast and black coffee are not enough for what your body needs at this time. After a long period of rest and digestion, your body needs some substantial new nutrients to fuel what should be the most active part of your twenty-four-hour day.

If you guessed that the opposite is true for the evening hours, you would be right. As the sun goes down and night approaches, your body is winding down all its processes for a good night’s sleep. Part of that winding down is lower cortisol levels. If you consume food during late hours, when cortisol is low, that food has a greater likelihood that it will not be turned to energy to accomplish a goal or task; instead, it’s likely to be stored as fat.

Harnessing the power of your CR in relation to food intake can have other significant positive impacts on your body. Even at the cellular level, following a CR cycle for eating and fasting (these can vary from daily routines to a discrete fasting schedule over multiple days) can improve biomarkers of disease. This includes cardiovascular disease, diabetes, improved insulin sensitivity, and reduced oxidative stress. It can also enhance metabolic function, lead to fewer cravings, and help you burn fat more efficiently.

Using your body’s own natural cycle to support your “feeding habits” can enhance weight loss efforts. Consuming food between approximately 7a.m. and 7 p.m. is the optimal time for your body’s needs. Try your best to establish an eating schedule within that twelve-hour window. Late night food intake has your CR and cortisol curve working against you. Leave your midnight snacks behind and ride the CR wave and cortisol peaks to maintain good eating habits that align with your body’s natural inner clock.


Nada Milosavljevic
Nada Milosavljevic

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