Health nuts from Hugh Jackman to Tim Ferriss are trying ‘intermittent fasting’ — the dieting fad that lets you eat anything


A diet that goes against convention wisdom on healthy eating is gaining traction among health nuts, including Hugh Jackman, “4-Hour Workweek” author Tim Ferriss, and tech workers in Silicon Valley. It’s pretty simple, with no calorie-counting or intense exercise regimen involved.

How it works, in a nutshell: Don’t eat during certain hours of the day.

When people practice intermittent fasting – the buzziest diet of 2017 – they go without food for anywhere from 14 hours to several days. Some techies say intermittent fasting helps them focus and be more productive, while others laud the diet as an easy weight-loss hack.

Here’s what you need to know if you’re thinking about trying a fast.

Hugh Jackman did not wake up like this.

20th Century Fox via YouTube screengrab

In 2013, the actor, who plays Wolverine, told Australia’s “60 Minutes” in an interview that he fasts for 16 hours out of the day while training for the big screen.

Alberto E. Rodriguez/Getty

Source: YouTube

“From about 10 in the morning till 6, for this, I eat way too much. And then nothing after that,” said Jackman, who apparently got the idea from Dwayne “The Rock” Johnson.

The most common intermittent fasts last between 14 and 36 hours. Giving up food and even the milk in your morning coffee can be difficult. But there’s one major perk — simplicity.


Dan Zigmond, director of analytics at Facebook and a seasoned faster, told Business Insider in 2016 that he and his friends have tried and abandoned other extreme diets over the years.

“Lots of us are eating at work or on the run. It’s kind of hard to control what you eat these days,” Zigmond said. “But one thing that basically everyone can control is time.”

A few years ago, a paper from the Salk Institute for Biological Studies crossed Zigmond’s desk. It suggested that when you eat could potentially matter as much as what you eat.

China Photos/Getty

Mice who were restricted to eating during only certain hours of the day were thinner than mice who were fed whenever, according to the study. They lost weight regardless of what they ate.

Still, the science behind intermittent fasting is spotty. Most studies use rodents and fruit flies as test subjects rather than primates and people, Scientific American reported.

Flickr/Global Pandora

Source: Scientific American

As interest in fasting picks up, the number of research papers published that mention fasting has steadily risen year after year, from 934 in 1980 to more than 5,500 in 2015.

The paper reminded Zigmond of his time living in a Buddhist temple in Thailand years ago. The monks followed a similar routine as the mice. So he decided to give it a go.

Jorge Silva/Reuters

“It took me a couple of weeks. I remember at the end of each day, I would text a friend and say how many hours I’d eaten that day,” Zigmond told Business Insider. “But I got pretty quickly to this nine-hour diet. I just loved it. I almost immediately felt better. And I started losing weight.”

He dropped more than 20 pounds in less than a year. Zigmond, a father and a practicing Buddhist, said he wakes up feeling refreshed and never goes to bed hungry.

Courtesy of Dan Zigmond

In 2016, Zigmond published a book about intermittent fasting called “Buddha’s Diet.”

Most people, especially those with some weight to lose, can take on a longer fast as long as they are medically supervised and in reasonable health to begin with.

Ben A. Pruchnie/Getty Images for lululemon athletica

Certain health conditions might be exacerbated by fasting.

It’s important to consult your doctor before attempting any kind of fast.

During a fast, the only thing you’re allowed to put in your body is water. Because roughly 20% of our daily fluid comes from what we eat, it’s extra important to stay hydrated.

Getty Images/Matt Cardy

“Many people who try the diet complain of things like headaches,” Krista Varady, a professor of nutrition at the University of Illinois, told Business Insider. “But the problem is a lot of them aren’t drinking enough water.”

A person’s fasting routine is incredibly personal. Author and self-proclaimed “human guinea pig” Tim Ferriss hopped on the bandwagon after a seven-day fast healed his joint pain.

Andrew “Drew” Kelly

Years ago, Ferriss checked into a fasting clinic after a bout of Lyme disease took a toll on his joints. He lay in the fetal position for nearly all seven days, drinking only distilled water.

He described the experience in his book, “Tools of Titans,” as “excruciating.”

Still, Ferriss said the fast helped heal his “long-standing skin issues” and chronic joint pain.

These days, Ferriss aims for a three-day fast once a month and a five- to seven-day fast every quarter. It helps him hit the reset button on his wellness and feel stronger.

Andrew “Drew” Kelly

Ferriss told Business Insider that since he began doing intermittent fasts regularly, he’s “had some very, very clear cognitive benefits,” including increased energy and focus.

Internet entrepreneur Kevin Rose was turned onto the idea after reading the research of Valter Longo, the director of the USC Longevity Institute and a leading expert on fasting.

Hollis Johnson

Rose also told Business Insider that the 2013 Hugh Jackman interview inspired his decision.

“Hugh Jackman is shredded, and [he’s] Wolverine, and that is impressive,” Rose said.

Rose stops eating as close to sunset as possible and usually enjoys his first meal the next morning at around 10 or 11. Rose said the diet helps him feel more focused and avoid sugar crashes. He no longer relies on a cup of coffee at 3 p.m. to power him through the afternoon.

In 2016, Rose launched an app called Zero, a simple tracker that helps users sync a fast with their biological clock. It counts down how many eating hours are left in the day.


Source: Business Insider

Phil Libin, who helped create the popular productivity app Evernote, subscribes to a more extreme version of intermittent fasting known as extended fasting.

All Turtles

The fall of 2017 marks one year since Libin, who now runs an artificial intelligence startup studio called All Turtles, started fasting on a regular basis. The tech executive gives up food for between two to eight days in a row every week, drinking only water, coffee, and tea.

Libin has lost 85 pounds, reversed a prediabetes diagnosis, and feels “25 years younger.” He told us, “I’m not fasting to lose weight anymore. I’m fasting because I really like it.”

There’s another major draw among Silicon Valley’s biohacking community: Studies in mice and primates suggest that temporarily abstaining from food may prolong life itself.

Christopher Furlong / Staff / Getty Images

When the body goes into fasting mode, it doesn’t produce as many growth-related hormones and proteins, which are also linked to cancer and diabetes. Instead, the body takes a break to repair cells. This “maintenance state” may be the key to unlocking longer lives.

The latest study on calorie restriction, published in September in the journal Nature, was run on mice and primates. Its results suggested that animals on a calorie-restricted diet had far fewer markers of a genetic process associated with aging. Their cells appeared “younger.”

In San Francisco, the WeFast club brings biohackers together for breakfast every week when they break a 36-hour fast. The group’s goal is to promote discovery and longevity.

Melia Robinson/Business Insider

For Michael Brandt, a WeFast member and cofounder of the “cognitive enhancement” supplements startup HVMN, it’s not just about living longer, but living better.

Melia Robinson/Business Insider

He told Business Insider that when he fasts, he doesn’t have to worry about indigestion or food comas. There’s never anxiety over where his next meal will come from. He can focus fully.

For this reason, the group gave a special nickname to the 36-hour fast: “the monk’s fast.”