How intermittent fasting can boost energy, productivity, and work performance

Maybe you already limit your own eating to a tight six-to-eight-hour window every day. Or perhaps you abstain for a full 24 hours a few days a week. If you don’t, odds are that more than a couple of your coworkers do.

A growing body of research suggests intermittent fasting has numerous health benefits. But how does a fasting diet impact your performance at work?

“From an evolutionary perspective, fasting is when your mind is working its best,” says Mark Mattson, PhD, author of The Intermittent Fasting Revolution and a professor of neuroscience at the Johns Hopkins University School of Medicine. “If you’re an animal in the wild that hasn’t been able to get food for a few days, your brain and body better be working optimally or you won’t survive.”

How does intermittent fasting work for those of us trying to survive the rat race in the wilds of the concrete jungle?

Is intermittent fasting healthy?

Many people credit intermittent fasting with weight loss. Some research suggests it has the power to stave off cancer, dementia, heart disease, and diabetes—even help with an all-out slowdown of the aging process.

It may be increased insulin sensitivity and reduced inflammation that underlie all these benefits. When you fast, your body responds better to insulin, the hormone that regulates blood sugar. With better overall blood sugar control and less circulating sugar to burn, the body resorts to burning fat instead.

Better blood sugar control and less body fat may equal less overall inflammation, which seems to play a role in many of the diseases that are connected with aging.

How fast are the effects of intermittent fasting?

Trying to prevent dementia that might not impact you for decades could arguably be enough reason to commit to rescheduling your mealtimes. But could intermittent fasting give you an edge before that too?

There aren’t a lot of studies into the more immediate effects of fasting on human brain performance. But animal research shows many examples of the benefits.

Studies in mice show that within a few weeks of adopting the new schedule, levels of brain-derived neurotrophic factor (BDNF) rose. This brain molecule plays a role in learning, memory, and forming new connections in the brain. BDNF keeps depression and anxiety at bay too.

“Once animals are adapted to intermittent fasting, we see anxiety levels drop, which makes them better able to concentrate, and then we see learning and memory improve,” Mattson says.

Better learning and memory on an empty stomach may sound counterintuitive. A lot of people would say they simply can’t think straight on an empty stomach. It hardly seems conducive to staying on top of your game at the office. But those feelings are fleeting.

“You’ve just got to adapt to it,” Mattson says. “It’s like exercise: If you haven’t been exercising and you start running, you’re not going to feel great at first. It takes a couple weeks to a month for your system to adapt.”

Once your body is forced to start burning fat for energy, rather than sugar, the fog should lift as your focus sharpens. Fasting can also improve sleep because you get digestion over with earlier in the day. Better-quality sleep brings its own host of benefits, including a sharper mind.

Set yourself up for success

There are a few different types of intermittent fasting schedules. One way sets a six-to-eight-hour eating window, where you get all your calories for the day within a certain period, say, 10 a.m. to 6 p.m. Outside that window, you only drink water, black coffee, tea, or other zero-calorie beverages.

Another option: Fast for a full 24 hours one to two days a week. A third involves choosing two or more days a week to take in only 500 calories, and eat normally on the other days.

Before you get started, keep in mind that “this is not for everyone,” says Caroline Susie, RDN, a spokesperson for the Academy of Nutrition and Dietetics. “If you are pregnant, breastfeeding, on insulin for diabetes, or have a history of eating disorders, we don’t want to go down this road.”

If you’re not sure if it’s safe for you, talk to your doctor. Once you’re ready, try these tips:

Start small

If you typically eat three square meals with snacks in between, spread across all your waking hours, suddenly fasting for 18 hours a day might be a stretch at first. Start with a 12-hour eating window, say from 6 a.m. to 6 p.m. Make that window a little smaller each week.

Don’t forget about nutrition

Some people think they can just eat whatever they want during their window. If you want to feel your best during fasting hours, and reap all the health benefits of this lifestyle, a well-balanced diet rich in fruit, vegetables, fiber, whole grains and lean protein, Susie says, “is going to tee you up for success.”

Remember to hydrate

You can drink all the water you want during fasting hours, and you should: “Some people will get headaches and misconstrue that as side effects of fasting, when they are just dehydrated.”

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