While fasting is often associated with religious holidays, this time-honored practice is more than a cultural tradition. It's become a buzzword in the health industry today — and for good reasons: Research shows fasting can have major health benefits on a cellular level, including supporting gut health, reducing inflammation, managing insulin levels, improving longevity and more.
Fasting may conjure up the image of noisy stomach growls and hunger pangs. However, the focus of intermittent fasting is not on “eating less,” but rather on shortening the natural schedule of eating to allow for an extended break for your digestion. The time you are not eating falls mostly while you’re asleep and the time you are eating falls — you guessed it — while you are awake.
“Every day we’re bombarded with the message: Eat less, lose weight,” says Frank Lipman, MD, Chief Medical Officer at THE WELL. “But humans aren’t wired to feel deprived all the time. More important than how much we eat is what we eat, but we also have to consider when we eat.”
"More important than how much we eat is what we eat, but we also have to consider when we eat."
Types of Intermittent Fasting
Intermittent fasting (IF) focuses on restricting the window of time in which you eat in order to give your digestive system time off to recover. There are several subdivisions of IF, and, according to Lipman, the easiest way to do it without having to go to extremes is simply to lengthen the day’s natural fast: the time between dinner and the aptly named “breakfast.”
A popular pattern for this type of fasting is the 16:8 method, meaning you eat your meals within an eight hour period and fast for the other 16 hours. This type of fasting can easily be tailored to your individual day and schedule. If you eat dinner at 7pm, wait until 11am the following day to have breakfast. You are allowed calorie-free drinks (like herbal tea or coffee) during the fast, but adding a creamer or sweetener (even a splash of almond milk) undoes the fast.
Time-restricted eating (TRE) is very similar to intermittent fasting, but emphasizes eating in sync with your natural circadian rhythms. Besides regulating energy levels during the day and sleep at night, circadian rhythms also impact metabolism. Lipman suggests eating most of your calories earlier in the day (when your metabolism is peaking) and having a small dinner early in the evening (when your metabolism is winding down).
Modified fasting (also called the 5:2 diet) follows a 5:2 ratio: You eat regularly for five days and then fast for two days. During those two days of fasting, you are allowed to eat five hundred calories total and drink unlimited calorie-free beverages.
Alternate-day fasting means alternating between eating one day and fasting one day. This could mean eating breakfast and lunch one day and then fasting twenty-four hours until lunch the next day.
A common thread: There are no restrictive rules about what you can or cannot eat during the "feeding window." This ease of eating is what attracts so many people to the idea of intermittent fasting — it can feel like a breeze compared to a strict, reduced-calorie diet!
That said, following a time-restricted eating plan doesn't mean you have free rein to eat anything you want. While there aren't oppressive dietary rules, you'll still want to use common sense, and mainly choose whole, nutritious foods — not chocolate cake and cheese burgers — to nosh on when it's time to eat.
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Science-Based Benefits of Intermittent Fasting
The majority of the benefits from this way of eating result from the break that it gives the digestive system in the hours between meals, research suggests. Digestion, after all, is hard work for your body: Five to 15 percent of the energy you expend in any given day is dedicated to it.
Here are a few of the positives that can come from intermittent fasting:
1 Lower insulin levels and burn fat
Time-restricted eating has been shown to lower blood levels of insulin and raise levels of growth hormone, which can promote fat burn and muscle gain, among other benefits.
“Since we burn calories more efficiently with less insulin during the day, that’s when we should be taking in most of our calories,” Lipman says. So finishing dinner by 6 or 7pm allows the body plenty of time to burn off calories before bedtime, keeping blood sugar balanced and weight off.
This proves particularly beneficial for people with type 2 diabetes, as fasting can help keep insulin resistance under control and help lower blood pressure.
2 Support Gut Health
Both IF and TRE help keep your microbiome in good shape, which helps maintain gut health — a key component to overall health and immunity.
“Research shows that when not eating, microbes in the gut work on repairing the gastrointestinal tract, offering protection from ‘leaky gut’ and the kind of systemic inflammation that can trigger chronic disease,” says Lipman. Additionally, a recent study revealed that after each meal, for around four hours, gut microbes leak into our bloodstream silently triggering inflammation.
3 Kickstart Cellular Repair
When your body is fasting, healthy cells begin repairing damaged cells — a process called autophagy — stripping out the still-salvageable parts and recycling them to use for energy and to create new cells. “Those generous fasting periods stimulate cells to clean house, purging the body of toxins and old cells that otherwise gum up the works and adding another layer of protection from inflammation, slowing down the aging process at the cellular level,” Lipman says.
4 Improve Cardiovascular Health
According to the World Health Organization, cardiovascular diseases are the number one cause of death globally. Two factors that play a major role in improving cardiovascular health? Decreased inflammation and low levels of LDL (bad cholesterol).
High insulin and blood sugar are associated with inflammation — IF curbs insulin levels, which in turn reduces inflammation. Studies have also connected IF with lowering levels of LDL and improving cholesterol, contributing to better heart health.
5 Boost brain health
While further research needs to be conducted on humans, studies have shown that intermittent fasting can help improve brain function by increasing growth of new nerve cells. Other research on mice has shown that it can increase levels of a hormone called brain-derived neurotrophic factor (BDNF), which helps stave off depression and other brain problems.
How To Ease Into Fasting
There may be less restriction on calories with intermittent fasting, but that doesn’t mean loading up on junk food either — you should still focus on three meals of nutrient dense foods within the time frame you are eating. It’s also important to ease into a fast. The body isn’t meant to go from zero to 60, so jumping right into a 24-hour fast can drastically increase stress on the body.
“Fasting is not a one-size-fits all diet. You have to find when it’s right for your body,” says Katrine van Wyk, Lead Health Coach at THE WELL. “Insulin and cortisol share a strong link within the body. If you’re energetically run down, or your blood sugar is unstable, you’re just adding stress to the body.”
Instead, start by eating dinner a little earlier and breakfast a little later and take note on how you feel. Then increase the hours of fast, continuing to check in with your body. If you feel low energy or worse, that’s a sign of your body’s limit.
If you have questions or want to see if fasting could benefit you, talk to your doctor or book an appointment with one of our Health Coaches.
The body isn’t meant to go from zero to 60, so jumping right into a 24-hour fast can drastically increase stress on the body.
A Few Caveats
Anyone can benefit from having an earlier dinner, but expanding the daily fast period beyond the 12-hour mark is not for everyone — especially women who are pregnant or trying to get pregnant, breast-feeding mothers, those with a history of eating disorders, children under 18 and those under high stress.
Before beginning, consult with your doctor to see if intermittent fasting is right for you and how to tailor it for your body and needs. Fasting may induce stress on your body that if not prepared to handle, may cause more harm than good.
Bottom line: Whether your meals fall within a structured time frame or not, focus on a healthy, sustainable plan to feed your body a balanced diet so you can feel your best.