The Circadian Clock of Fat Cells By: Megan Kelly (CNP)
We accept the concept of circadian rhythms as they apply to sleep and hormones, but what if they were affecting your fat cells as well!?
A recent study suggests that, in fact, they are!
In the study, participants with relatively normal circadian rhythms underwent some restrictions for 10 days in order to keep their routines and meals regulated. Then, over the course of three days, their sleep and meal times were regulated in cycles. Finally, participants were placed in a 37 hour “constant” routine. This involved no changes in light/dark, feed/fast, and sleep/wake cycles. Daylight and temperature were strictly controlled and food was evenly distributed to rule out any other impacts on the fat cells’ metabolism.
Researchers biopsied the fat cells every 6 hours, and measured the gene expression to figure out how functions changed throughout the day. They determined that there were very clear distinctions between fat cells in the morning and at night.
Gene expression independent of light and feeding happened at specific times of the day, telling us that the time of the day itself matters when it comes to fat cell activity.
During the night, fat cells performed antioxidant actions and metabolized organic acids and broke down fat.
Contrastingly, during the daytime, fat cells were more involved in active function, like regulating gene expression and nucleic acid binding.
In the morning, genes in fat cells work on the deeper functions in our DNA like transcription and translation.
Since fat cells are an active hormonal tissue, they influence appetite and metabolism, and they have their own independent time-based rhythms.
From studies like this one, we are learning more and more about cellular function and gaining insight into how lifestyle elements like fasting, food intake timing, sleep and time of day can have deep impacts on our cellular health.
How Can You Optimize Your Circadian Rhythm?
Here are a few suggestions to get you started:
1) Avoid Blue Light at Night
Blue light tells your brain that it is daytime, interrupting your ability to make the hormones and neurotransmitters you need to fall asleep! In the evening, consider using lamps instead of any bright overhead lighting, avoid using your phone or laptop, turn of your TV when the sun goes down, or try some blue blocker glasses if you don’t want to do any of the above. It may also help to wear an eye mask while sleeping.
If you really want to use your computer and phone at night, you may also consider downloading an app that reduces the amount of blue light emitted from your device. Try the “Flux” app for computers and “NightShift” for iPhone.
2) Time Restricted Feeding
Restricting your daily eating window to 12 hours or less, ideally during the daytime, may be ideal for supporting circadian rhythms. Recent studies suggest that we actually see greater benefit from skipping dinner in an effort to intermittent fast than skipping breakfast. Due to circadian rhythms, our insulin sensitivity is better in the morning than at night!
Even if you don’t want to skip dinner, however, you will likely benefit simply by stopping eating at 7pm and not eating again until 7am the following morning.
3) Expose Yourself to Sunlight During the Day
Ideally, get at least 30 minutes outdoors each day, preferably in the morning. Many people also benefit from a “Happy Light” indoors to mimic sun exposure, especially in the darker winter months.
REFERENCE: Circadian regulation in human white adipose tissue revealed by transcriptome and metabolic network analysis. Scientific Reports, 9(1), 2641. https://doi.org/10.1038/s41598-019-39668-3 Christou, S., Wehrens, S. M. T., Isherwood, C., Moller-Levet, C.S., Wu, H, Revell, V. L., … Johnston, J. D., (2019).