Twitter CEO Jack Dorsey has come under fire for his incredibly strict 'wellness' regime, which includes only eating one meal a day.
Dorsey also fasts on weekends, drinking only water.
He's been criticised for his extreme diet, drawing fire for promoting unhealthy and dangerous eating practices.
The 42-year-old has been meditating regularly for about 20 years, and adopted his ascetic approach after attending a 10-day Vipassana retreat.
Vipassana means 'insight into the true nature of reality' and involves not eating after noon, two-hour meditation sessions and no reading, writing or devices.
"It's all about detaching yourself," Dorsey revealed to the Ben Greenfield Fitness podcast.
"I try to go as deep as I can in terms of building that single point of focus and building that clarity that I experience directly during those 10 days."
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"The first time I did it, like day three, I felt like I was hallucinating. It was a weird state to be in.
"But as I did it the next two times, it just became so apparent to me how much of our days are centred around meals and how - the experience I had was when I was fasting for much longer - how time really slowed down."
But while Dorsey may have nothing but positive things to say about his experience, experts and media outlets have criticised his lifestyle and comments strongly.
New York Magazine was among those to deliver a stinging takedown.
"That's not telling people they should buy some dumb light bulb that probably doesn't do squat for their health," journalist Madison Malone Kircher wrote. "That's evangelising highly restrictive eating practices from a lofty platform where people might take them as universal truth."
Eating disorder expert Allison Chase was similarly condemning. She told HuffPost that Dorsey's diet could easily spiral into an eating disorder.
"Labelling such behaviours as 'wellness' gives the false notion that it's a healthy lifestyle, which it's not, and can encourage others to follow suit," she said.
"This can be especially detrimental to those who are battling, in recovery from or predisposed to an eating disorder."
Even the tech boss admits he struggled with his regime early on, when he was doing his first Vipassana retreat.
"Every day I would wake up and I would look forward to two things: hot oatmeal and honey nut Cheerios. There was one day I remember... the oatmeal was cold and I was like, 'Oh man, this is the one thing I look forward to every day'."
As if eating just five meals a week wasn't enough, Dorsey also starts his day with a 5am ice bath.
"I feel like if I can will myself to do that thing that seems so small but hurts so much, I can do nearly anything."
"Nothing has given me more mental confidence than being able to go straight from room temperature into the cold," he added.
Dorsey meditates for an hour at both ends of the day and also enjoys hot saunas - followed by another ice bath.