New Research Looks Into How Intermittent Fasting May Change The Internal Clock

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Unless you’ve been totally off the grid, there’s a good chance you’ve heard about intermittent fasting (IF). The list of IF’s benefits is long and includes weight loss, blood sugar balance, and reduced inflammation. 

A new study helps1 us gain insight into how fasting might affect less obvious parts of our health, specifically our cells’ internal clocks, which control our daily sleep-wake cycle. 





How fasting affects the internal clocks of our cells

For this animal study, researchers separated mice into two groups and fed them the same high-calorie diet. One group got unlimited access to the food, while the other group was limited to a nine-hour eating window, which means they fasted for 15 hours a day. The mice were observed for about 7 weeks, then tissue samples were taken throughout the body and evaluated for genetic changes. 

The results, which were recently published in Cell Metabolism, showed that 70% of genes responded in more than 22 regions of the body—including in the liver, stomach, brain, adrenals, heart, lungs, and intestines, among others—to time-restricted eating. The findings also showed that many of the areas in the body in charge of hormonal regulation, including the circadian rhythm (which is regulated by the hormones cortisol and melatonin) were affected by time-restricted feeding.

Your own 24-hour clock.

Your circadian rhythm helps your body run on a roughly 24-hour cycle. Think about how you tend to get sleepy when the sun goes down, which happens because your body starts producing melatonin as it gets darker outside. 

This study shows that IF has a role to play in this 24-hour clock, as well as the way cells behave over time. As Satchidananda Panda, Ph.D., a senior author of the study, explains, “Circadian rhythms are everywhere in every cell.” And the results of this study showed that time-restricted feeding synchronized the circadian rhythm in cells in a way that promotes health.

More specifically, the data showed that 40% of genes in three areas of the body (the adrenal gland, hypothalamus, and pancreas) were affected by time-restricted eating. “We found that time-restricted eating synchronized the circadian rhythms to have two major waves: one during fasting and another just after eating. We suspect this allows the body to coordinate different processes,” Panda continued.

This coordination may be able to promote health and fend off disease. Previous research by the same authors showed that time-restricted eating could improve the health of firefighters, who often experience circadian rhythm disruptions due to their work schedules. 

How to support your circadian rhythm today.

This study was performed on mice and only fills in some of the gaps in knowledge we have about how intermittent fasting affects our body on a molecular level. Fortunately, we already know of other ways to support our daily cycles and overall health: 

1. Get sunlight first thing in the morning.

When sunlight comes in through your eyes, your brain picks up the cue that it’s daylight and time to get up and be active. This is why many health experts recommend stepping outside first thing in the morning if you can. 

2. Avoid blue light in the evening.

Conversely, blue light (like the light from our phone screens) is known to disrupt evening melatonin production and throw off our rhythm. Avoiding screens one to two hours before bed can help. 

3. Have a consistent bedtime.

Having a consistent bedtime (even on weekends) can help keep your sleep-wake cycle regulated so you can avoid symptoms like fatigue and brain fog. If you have trouble falling asleep, try one of these nine effective sleep aids

4. Don’t eat late at night.

A great way to start time-restricted eating is to avoid late-night snacking. This can help you easily extend your daily fasting window

5. Manage stress.

Your daily sleep-wake cycle is regulated by melatonin and cortisol, which is often called the stress hormone. This means that if you’re struggling with chronic stress and high cortisol, the interplay between these two hormones can start to go awry. Whether you turn to meditation, exercise, or talking with a friend, having a strategy to help keep stress levels in check is key.

The takeaway.

A new study shows that time-restricted feeding can affect your cells’ internal clock in ways that promote health. There’s still a lot more to learn, so for now we can support our body’s natural rhythms by getting plenty of sunlight during the day and darkness at night, stressing less, and consistently going to bed at the same time.


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