Last November, Phil Libin stopped eating. The idea came to him over coffee with his friend Loïc Le Meur. A fellow entrepreneur, Le Meur was in the middle of a three-day fast, and he couldn’t stop talking it up. The health benefits! Weight loss! Longer life! It sounded insane. “I decided I would go home and research this fasting thing just so I could prove to him that he was being an idiot,” says Libin.
But the more he Googled, the more the internet revealed that a growing number of people — and not just any old people, but scientists — thought there were benefits to the practice. “I was like, holy crap,” he remembers. “Unlike everything else, this is the first theory that felt complete to me.”
At the time, Libin was fat, and he thought this was a problem. His uniform startup t-shirt stretched taut against the bulge of his belly. He weighed around 258–260 pounds, nearly the heaviest he’d ever been.
Since his last year of high school at New York’s Bronx Science, Libin had been pudgy. When he was in his twenties, starting and building software companies, he didn’t care. “It was a spectacularly bad idea, but I just had decided that I’m going to totally not worry about my health until I’m 45,” he remembers. “But then as soon as I turn 45, then I’m going to take it really seriously.”
By last fall, Libin’s personal deadline was approaching. He was due to turn 45 in January. In recent years, he’d tried to address his weight through diets and exercise, and he’d often succeed in losing 20 or even 30 pounds, but then inevitably, the weight would creep back. He’d been to his doctor for testing and blood work; the doctor told him that if he kept things as they were, he’d have type two diabetes within five years.
Also, he wanted to start a company. It’d been more than a year since Libin had left the board of Evernote, the digital note-taking company he’d joined as CEO in 2007. As a partner with General Catalyst, he’d been investing for a while. As much as he enjoyed it, he was restless—but he wasn’t sure about becoming a CEO again. “I thought, I gotta at least prove to myself that I can govern myself, before I’m ready to govern a company.”
So, Libin tried not eating for a day. “I was, like, hungry, but it wasn’t a disaster,” he recalls.
The following week, Libin decided to try a 72-hour fast. The first day was hard. The second day was even harder. But on the third day, he felt amazing! “I got out of bed feeling better than I’d felt in 20 years,” he says. “I was in a very good mood, and felt really clear.”
Seven months later, Libin fasts regularly between two and eight days at a time. He has lost 81 pounds, and now his T-shirt hangs loosely beneath well-tailored sports jackets, his features assuming a new definition on his face. And while the weight loss may have been the original goal, Libin is addicted to the way he feels when he’s not eating. “My mood is radically and sustainably better than it was before. I would describe it as almost like a very mild state of euphoria,” he says. “At this point for the past couple months, I haven’t been fasting to lose weight. I’ve been fasting because I’ve craved the feeling of fasting.”
First, you should know that Libin isn’t trying to disrupt eating. He’s not saying you should fast. He takes pains to enforce that he is not an expert. He can only say definitely what has worked for him. But it has worked so well for him.
When he first sought medical advice on fasting last fall, his doctor told him it was important to eat regular meals daily. “I thought, ‘that’s just random nonsense that you’ve heard somewhere. I don’t believe it,’” Libin recalls. When, after fasting for awhile, Libin returned to the doctor, the test results spoke for themselves. “I showed my doctor all my blood work from three years ago, and he was just like, ‘You’re literally 25 years younger.’”
As Libin got more serious, he began to monitor his health. He takes a multivitamin and a vitamin D tablet daily. And when he’s not eating, he drinks mineral water to make sure he’s getting enough sodium. In January, his friend Daniel Gross gave him his first continuous glucose monitor. Gross, a wiry 25-year-old Israeli who is a partner at Y Combinator and sold the machine-learning company Cue to Apple in 2013, is also a fan of fasting, but for different reasons. He’s obsessed with longevity and believes fasting will help him live longer. He even started a WhatsApp group called “Fast Club” to coach other fasters. (“It’s like Fight Club,” says Gross. “The first rule of Fast Club is…” He then proceeds to tell me all about it.)
The glucose monitor, which Libin wore for a month, measured his levels in real time. A tiny electrode was inserted under the skin, and it sent information via transmitter to a monitoring device that he wore around his abdomen. He would use the measurements to infer insulin and insulin resistance. “You get benefits of lowering insulin resistance pretty early,” says Libin—and he says that’s true even if you’re only fasting for short periods.
He explains that when you fast for a longer period, your body enters ketosis. This is a word that Libin, Gross, and Le Meur all use a lot. By definition, it’s a metabolic state in which your body burns fat instead of carbohydrates. “Ketosis is what gives you some of the mood effects and the mental clarity and the emotional benefits,” Libin says.
The other word that comes up often when talking to these guys is “autophagy.” Says Libin: “That’s when your body starts eating itself, which sounds bad, but is actually super good for you.” It’s a recycling system your cells use to generate nutrients from their damaged components. “One of the scientists who won the Breakthrough Prize — Yuri Milner’s new thing where he’s giving awards for fundamental science — his whole work was on autophagy,” says Libin. He’s referring to the Tokyo Institute of Technology cell biologist Yoshinori Ohsumi, who also won a Nobel Prize for his research. “The serious study and research of understanding the cellular effects is just a few years old, and happening right now,” Libin says.
After months of trial and error, Libin has arrived at an erratic fasting schedule that is pegged to events that necessitate meals. If he’s coming through New York, he’ll plan to eat a bagel. If he is in Tokyo, he’ll have ramen and feel good about it. “I basically settled on several days of no calories, followed by a few days of eating normally,” he says. “I eat when I have a really good reason to eat. I haven’t eaten since Sunday,” he says. It is Friday afternoon. “I will eat tonight because I haven’t seen this friend I’ll see tonight in a long time.”
Since Libin started fasting, meals have gotten way more fun. “It feels like I’ve got 3D smell,” he says. “I’ll sit at a restaurant and I can tell what the people behind me are eating.”
He has found it surprisingly easy to be around food, which is good because most business events seem to involve sitting down to a meal. He’ll order coffee, tea, or water and pass the dishes around without desire to partake. “It is a very pleasurable way to experience food without actually eating it,” he says.
I ask if his food abstinence is awkward for his dinner companions, and he considers this. “Socially awkward is my middle name,” he says, with the assured self-mocking that comes from decades of being the nerd, and having landed in a culture where nerds call the shots. “I’m not a well-adjusted extrovert. In San Francisco, everyone expects you to do something weird, so in my day-to-day life, it’s fine.”
Besides, other people are doing it. Lots of other people.
Recently, Silicon Valley’s biohacking, metrics-obsessed, longevity-seeking founders have embraced fasting with all the fervor they brought to their newly hatched meditation practices five years ago. They form clubs and gather for breakfasts. At one startup, the entire staff has fasted together. Digg founder Kevin Rose has even created an app to help you track your fasting.
Libin belongs to the smaller crew that takes it to the extreme. He knows about intermittent fasting, which is the practice of going for several hours a day without food, or eating just one meal a day. But Libin doesn’t really think skipping a meal or two counts. “People who are doing 16/8,” he says, referring to a schedule in which you fast for 16 hours of a day and eat regularly during the remaining eight, “to me that’s not fasting. That’s eating.”
These guys didn’t invent fasting, intermittent or otherwise. In fact, Gross grew up fasting. As an Orthodox Jew in Jerusalem, he fasted for Yom Kippur. He is no longer practicing, but he uses this experience to suggest that maybe the ancients knew something about the health benefits of fasting that we don’t. “If it might be good for me, and there’s not a reason it’s bad for me, then I might as well do it,” Gross says. Many other religious traditions embrace fasting. This month, for example, practicing Muslims are observing Ramadan.
For all the dudes signing off food, there are few women fasters, which is something the guys all acknowledge. Gross knows of a few. There is at least one female member of Fast Club at the moment. Le Meur, who originally got Libin into fasting, says he knows of none. “It’s only guys. I have no idea why,” he says. At a recent tech conference, Libin says a few women asked him about his new diet, and told him they’d heard women shouldn’t do it. Indeed, there are many blog posts among Paleo enthusiasts that suggest fasting may have different, potentially negative effects for women. But the research is scant, and only on rats, so it’s hard to say for sure.
There’s not much research available, period, to prove that fasting can do any of the numerous things its proponents hope it might, like living longer or preventing cancer. To people like Libin, it’s like a new software API—a great tool that could unlock all sorts of new opportunities in his body. He’s attacking the problem set of how to program his fast with all the concentration he applied to manipulating javascript in the early aughts. It’s biohacking, and he’s gotten pretty good at it. “There’s a few really surprising things that came out of this for me,” he says. “One of them is how predictable it is. At this point, I know what’s going to happen. I can calculate what I’m going to weigh next week, and in two weeks, if I do this, and this, and this. The math is consistent.”
By his calculation, he can pretty much sustain his new look — and all the feels that come with it — forever. And given that he’s become so good at governing himself, surely he can run a new company.
