On the short list of stuff we all need to survive, “food” is usually ticked off first, followed by “water” and “shelter.” But new research on fasting, or taking an extended break from the old feedbag, suggests a long stretch without food could ward off disease and extend your life.
Already, there’s evidence that periodic fasting has major weight loss benefits. Two recent studies found people who went 24 to 48 hours a week with little to no food lost significant amounts of weight—even when allowed to eat however they wanted on non-fasting days.
More research on so-called “intermittent fasting” indicates the practice may extend your lifespan, and stop or reverse the kind of cell damage that leads to heart or brain diseases.
Some of these findings have only been demonstrated with animals test subjects. But they’re still tantalizing. “The results so far are very promising,” says Luigi Fontana, MD, PhD, a researcher and professor of nutritional science at Washington University in St. Louis and Italy’s Brescia University. “In animals we’re seeing significant increase in prevention of multiple diseases.”
Of course, the transition from the animal world to the human world is not always a smooth one when it comes to promising medical research. But Fontana says there’s reason to be excited.
When you eat all day every day, as most Americans do, your body runs on the short-term supplies of energy your body stores in your liver, he explains. But if you take an extended break—around 16 to 20 hours—your liver’s energy stores run out, and so your body has to “rearrange priorities” in order to keep you fully functional.
At some point in this rearrangement, old or damaged cells begin to break down, and your body uses them as fuel to generate new cells. “Healthy cells start to eat dysfunctional proteins, organelles, and mitochondria, like a cleaning out of cell garbage,” Fontana explains. “We know that the accumulation of this molecular garbage leads to multiple diseases, so inducing the body to clean up this garbage may be very beneficial.”
This analogy gets thrown around a lot among cell researchers, but think of it like a forest fire; destruction often leads to healthier regrowth. “I think it’s possible that fasting for 15 or 20 days every five or 10 years could help the body remove all this garbage,” Fontana says. And that might explain why the preliminary research has linked fasting to longer, healthier lives.
At the same time, Fontana says the ability to monitor this kind of cell activity is pretty new. There are many unanswered questions.
Also, fasting is risky business. Nutrient deficiencies are a big concern. And because your body is accustomed to eating all the time, going just half a day without food can throw off your circadian clock, and mess with your mood, energy levels, and sleep.
But one thing is clear: “Taking in calories all day is not healthy,” Fontana says.