I’m all about circadian fasting, in particular. This lifestyle is designed for busy people who want an easy, healthy version of fasting that is also backed by medical literature. Here’s what to know about it.
What Is Circadian Fasting?
‘Circadian fasting’ is a term I coined for a type of intermittent fasting that is based on the emerging science of the circadian rhythm, the 24-hour cycle your body follows each day. Circadian fasting is focused on taking short, logical breaks from food at times that support your circadian rhythm. Basically, you’ll fast for a few hours before and after sleeping.
I have found that this approach can transform your health by supporting insulin sensitivity (and even warding off diabetes) and offering anti-inflammatory benefits.
Unlike fasting, in which you eat for eight hours or fewer per day, which can seem daunting for someone with a demanding lifestyle, circadian fasting can be incredibly straightforward. This type of eating is aimed to improve your overall health—not just promote short-term fat loss.
How Circadian Fasting Works
Every cell in our body needs a rest from breaking down and utilizing food. When your body senses a fasting state, it can focus on repair and renewal. These pathways are designed to run in the evening and overnight hours, but they seem to get turned on once we are in the fasting state as well.
Studies have shown that the timing of our meals matters greatly, even with the same amount of food. In one study published in Cell Press, researchers found that mice who ate an unhealthy diet could mitigate some of the effects by intermittent fasting in a circadian fashion, meaning they stopped eating two or three hours before bed and fasted for at least 12 hours. In short: Circadian fasting offered mice metabolic benefits, even when they ate an unhealthy diet.
Of course, I’m not recommending you eat a junk food diet during your feeding hours. You’ll reap the most benefits from circadian fasting by focusing on clean, whole foods and plant-heavy meals (and managing your sleep).
How To Practice Circadian Fasting
The easiest way to kick off circadian fasting is with a 12-hour fast. This is surprisingly short, considering the average American eats 15 to 16 hours per day. The goal here is simply to overlap your fasting hours with your sleeping hours, minimizing the time you spend fasting while awake.
After your 12-hour fast, you can enjoy a mini breakfast packed with healthy fats and protein, like a handful of nuts or a smoothie. Then, eat as you normally would for the remaining 12 hours of the day.
When planning your fasting time frame, aim to start your fast two or three hours before bedtime. Get a solid seven to eight hours of sleep, and then do a fasted workout in the morning before breaking your fast, if possible. Then, during your eating window, aim to eat as many vegetables, fermented foods, and fiber-rich meals as possible. Switching to a plant-focused diet, staying hydrated, and avoiding sugar may also increase your results.
Continue following this pattern for two weeks.
After those two weeks, your 12-hour fast should feel pretty habitual. At that point, you can then increase your fasting hours to 15 to 16 hours on about three days a week. This will take your fasting to the next level, and you will begin to reap the benefits of metabolic switching (your ability to switch between using sugar and fat, including body fat, for fuel).
Once you do this, you should start seeing your health improve in a few ways. This may include an increase in energy, a healthier gut, increase in metabolism, fat loss, or improved insulin sensitivity.
Dr. Amy Shah, M.D., is a double board-certified physician with training from Cornell, Columbia, and Harvard Universities. With extensive training in health and nutrition, she advises on increasing energy levels, fixing gut issues, managing allergies, and boosting the immune system. Dr. Shah was recently named one of MindBodyGreen’s Top 100 Women in Wellness to Watch and is a member of Genexa‘s Medical Advisory Board.