For the past 18 months, Shawn Baker has eaten about 4lb of steak every day.

“I’ve got two rib-eye steaks waiting for me when I get off this call,” said Baker, a trained orthopaedic surgeon, from Orange County, California. “It can be monotonous eating the same thing over and over again, but as time goes by you start to crave it.”

The 6ft 5in bodybuilder, in his 50s, is one of a growing number of people experimenting with the “carnivore diet”, a regimen that involves eating only animal products like meat, offal and eggs, and no plant-based foods. It’s an extreme version of the low-carb, high-fat ketogenic diet – which trains the body to run on fat rather than carbohydrates – that has become popular in recent years. Proponents of the diet say it reduces inflammation and blood pressure while increasing libido and mental clarity.

Baker, who is nicknamed the “Carnivore King” and has amassed a cult following on social media, says the diet is easy because he doesn’t have to plan meals or count calories. “I just have to think: how hungry am I and how many steaks do I want to eat,” he said.

Before becoming a pure carnivore, Baker was also eating salads, spinach, dairy and nuts. Ditching these plant-based foods has been transformative for his body and athletic performance, he says.

“My joint pain and tendinitis went away, my sleep became excellent, my skin improved. I no longer had any bloating, cramping or other digestive problems, my libido went back to what it was in my 20s and my blood pressure normalised,” he said.

Although most medical practitioners balk at the idea of their patients ditching fruit and vegetables, the all-meat diet has been embraced by a cluster of cryptocurrency entrepreneurs, who describe themselves as “bitcoin carnivores”, a phenomenon previously reported by Motherboard.

“Bitcoin is a revolt against fiat [government-backed] money, and an all-meat diet is a revolt against fiat food,” said Michael Goldstein, a “bitcoin and meat maximalist” based in Austin, Texas. “Once someone has grown capable of seeing beyond the lies and myths that experts peddle in one domain, it becomes easier to see beyond them in other domains as well.”

Goldstein, who runs a website dedicated to carnivory called Justmeat.co, eats 2-2.5lb of “very rare” rib-eye steak each day, at a cost of about $400 a month. He says he never has cravings for pizza, chocolate or vegetables. “They don’t even register in my brain as food.”

He argues that eating only meat has freed up his time to get more work done. “Grocery shopping takes all of 10 minutes, most of which is standing in the checkout line. I spend little time thinking about food. I only need to eat once or twice a day (no snacking or cravings). Basically, it’s the greatest productivity hack, and Silicon Valley should have listened to me about it while I was there.”

Saifedean Ammous, a bitcoin economist, agrees, citing a “huge improvement” in productivity.

“The ability to focus for long periods has been life transforming, and was the reason that I managed to write a 300-page book, on bitcoin, fittingly enough!” he said.

Lily Chien-Davis, a social media specialist at San Francisco-based startup Heads Up Health, says that the enhanced productivity and mental clarity explains why this diet, like intermittent fasting, is popular in Silicon Valley.

She started eating a very low carb diet when her husband was diagnosed with cancer – some studies indicate that a ketogenic diet can help the body fight tumours. However, Chien-Davis found that changing her eating habits alleviated her pre-diabetes.

In February, she switched to a carnivore diet. “In 30 days my mood improved, I got stronger. It gave me extra energy and performance,” she said, adding that it also helped her come off her medication for bipolar disorder. “My friends all are curious about whether I have scurvy or have problems pooping. But I’ve been more regular than ever!”

The most challenging aspect of the diet is socialising with non-carnivores, said Ammous.

“Many carnivores encounter hostility,” he said. “It’s quite startling that when I used to eat junk food all the time, nobody ever got offended or worried by my diet, but they can get really agitated when I tell them I don’t think plants are good for me!”

Chien-Davis agrees: “You feel like a weirdo when you tell people about it, people are like ‘oh my God you are crazy’.”

Those who publicly discuss their adherence to the carnivore diet find themselves clashing online with vegans over their dietary choices.

Travis Statham, a New York-based software engineer and admin for several online communities dedicated to carnivory, will sometimes eat four to six quarter-pounder burger patties from McDonald’s for lunch.

In Statham’s view, vegans who are concerned about the slaughtering of cows are not thinking about the “monoculture of giant machines killing mice and other animals” in the fields used to grow crops, the displacement of wild animals that used to occupy farm land, or the spraying of herbicides and pesticides.

Baker, who regularly mocks vegans on his Instagram account, said that contrary to his posts, “most vegans are wonderful people trying to do the best thing”. He said that people who eat a vegan diet for health, rather than ethical reasons are good candidates for the carnivore diet.

“If your personality allows you to be extreme on a vegan diet you may be just as willing to do a carnivorous diet,” he said.

Christopher Gardner, a professor of medicine at Stanford University, is less convinced by the evidence.

“Are these T rex? African lions? Or humans? Assuming [you are referring to] humans, this sounds disastrous on multiple levels,” he said.

The lack of dietary fibre in an all-meat diet is likely to wreak havoc on the bacteria in our colons, known as the microbiome, he said. “Growing evidence suggests that in the absence of adequate fibre, the bacteria in the colon consume and thin the protective mucus lining, which then leads to impaired immune function and inflammation.”

Eating more meat also contributes to a rise in a substance called trimethylamine N-oxide in the blood which, according to research by the Cleveland Heart Lab, may be as bad for heart disease as saturated fat and elevated cholesterol.

Factory farming of animals is also linked to antibiotic resistance in humans and is a huge contributor to the greenhouse gases that contribute to global warming.

“In summary, I think a ‘carnivore diet’ is inappropriate for human health, bad for the health of our planet, abusive of the human labour force that handles the preparation of meat, abusive of animal rights and welfare,” he said.