Circadian rhythms and circadian misalignment
Did you know that the body has one master clock that is located in the brain? This master clock communicates with every organ system in the body to regulate physical, mental, and behavioral changes in a normal daily cycle. This is referred to as circadian rhythm or "around-the-day" rhythms. We call attention to this topic because aligning our nutrition choices with what the body is naturally designed to handle may be an effective strategy to improve health outcomes, including weight loss. (65, 66)
When our master clock is out of sync, this is known as circadian misalignment. A good example of circadian misalignment that you may be familiar with is jet lag, which occurs when your body's accustomed natural pattern of daylight and darkness has become shifted due to traveling across time zones. Those feelings of fatigue, irritability, brain fog, sleep disturbances, and altered digestion often arise as your body tries to keep up with the new schedule. Of course, jet lag isn't the factor that can disrupt the body's circadian rhythm. Other common circadian disruptors include:
- Bright light exposure at night
- Sleeping during the day
- Food intake at night
- Time zone travel (jet lag), social jet lag (staying up and waking up later on the weekends), metabolic jet lag (delaying meals on the weekend)
- Erratic eating patterns
- Skipping breakfast and consuming the majority of calories in the later portion of the day
- Shift work (67)
As you are reflecting upon your current patterns, it's important to note if any of these factors affect your current lifestyle. If so, there are strategies we can put into place to help reverse the negative impact they have on circadian rhythms. More on this to come!
Circadian rhythms and weight loss
Research has shown that short-term circadian misalignment, similar to that which occurs acutely with jet lag and chronically with shift work, may result in systematic increases in meal glucose responses, insulin, and other lifestyle factors such as sleep quality. (68)
There are a few important hormones at play here, and a key player is cortisol.
This hormone has its very own preferred schedule. It increases at certain parts of the day (morning) and decreases at others (evening). From a biological perspective, this makes sense. A morning cortisol rise helps us wake up to start the day, while the evening decline winds us down for a proper night's sleep.
When this pattern becomes erratic, adverse health outcomes may occur, including an increased risk for obesity and/or difficulty losing weight. (69)
To help keep your circadian rhythm functioning strongly in its preferred state, there are a few key strategies to consider:
- Get sun exposure first thing in the morning. If sun exposure isn't possible due to seasonal changes or work schedules, consider using a light therapy lamp such as
- Limit blue light exposure in the evening. If possible, limit screen time after a certain hour. Explore your phone settings to monitor screen time and set a downtime schedule.
- Align your meal size with the timing of your meals. If possible, opt for larger meals earlier in the day and limit larger portion sizes of higher-carb meals in the evening hours.
- Avoid caffeine after 3 pm.
- Prioritize a consistent sleep schedule with the same bedtime each night.