How To Fast: No Downside To Intermittent Fasting With Several Proven Health Benefits, According To Science

From wellness circles to religious observances, fasting is practiced by people from all walks of life and for a variety of reasons.

In fact, a recent US investigation showed that 10% of Americans say they engage in some sort of fasting regimen. That’s more than other popular eating practices like vegetarian (3%), Mediterranean-style (5%) and keto (7%).

But are there any real health benefits to controlled calorie restriction? And how do people know if they should try fasting?

“There doesn’t seem to be a downside to intermittent fasting or … restricting any eating you do to a certain number of hours a day,” National Geographic writer Fran Smith told ABC OTV.

Smith explored the science behind fasting for the publication’s new “Mind, Body, Wonder” series.

“You don’t have to eat three times a day. Or every three hours. No. We are not babies. Sheba Medical Center, Smith told.

decades of research show the benefits of fasting, Smith found. It is good for controlling blood sugar, supporting heart health, reducing excess weight, protecting against chronic disease, and possibly delaying cognitive decline.

It can even help reverse the effects of aging.

“(Intermittent fasting) promotes this cellular process called autophagy, which is a fancy way of saying self-eating. Your cells devour their own debris on their own, which allows the cells to replenish themselves with really functional components and function much better,” Smith said.

Smith clarified that this research does not extend to multi-day fasting, which can lead to muscle loss and other issues.

But short-term food-free intervals can work for almost anyone, even those with physically demanding lifestyles. A study showed that San Diego firefighters working during California’s grueling fire season responded well when a fasting regimen was introduced.

“There were no performance issues, and in fact the diet showed all sorts of benefits… They definitely showed improvements in their heart function and in their sugar levels,” Smith said.

From skipping breakfast daily to changing eating habits weekly, researchers have experimented with a wide variety of fasting protocols, even on themselves. The ideal ratio of how much to eat and when may exist, but science has yet to figure out what it is.

“One of the really interesting things for me in reporting this is how many scientists in the field of aging and longevity are actually fasting… They’re convinced by the evidence,” Smith said.

The bottom line: find out what’s right for you.

“Any fasting protocol is better than no fasting protocol,” Smith said.

In his reporting, Smith discovered that a researcher even devised a diet that tricks your body into thinking it’s fasting. Learn more about NatGeo.com.

The Walt Disney Co. is the parent company of National Geographic Partners and this ABC station.