If you are reading this over breakfast and want to be a part of the latest diet fad, then simple. Take a tablespoon, lift the butter dish and stir two great dollops of the yellow stuff into your coffee. Add a dash of oil - medium-chain triglyceride, if you’ve got some lurking next to the marmalade jar, and hey presto: one steaming cup of Bulletproof Coffee, otherwise known as the “fat black”.
The heady brew, caramel-brown with an unhealthy oily sheen, if done correctly, measures up to a whopping 500 calories per cup. It also tastes like the bottom of an industrial butter churn. But this is the new weight-loss craze that is sweeping the United States and now creeping into Britain. All hail the “new power drink of Silicon Valley”, coming to a café near you.
The coffee, whose lardy contents have left nutritionists shaking their heads in dismay, has been developed by tech millionaire Dave Asprey. The 41-year-old was once 21 stone, but that was before he discovered the “power of butter” at 18,000 feet during a hike near Mount Kailash in Tibet.
“I staggered into a guest house from the minus-10 degree weather and was literally rejuvenated by a creamy cup of yak butter tea,” so Asprey’s story goes. Now slimline, and still talking with the giddiness of somebody recovering from a bout of altitude sickness, he professes to be a “bio-hacker”: a man who can manipulate his own biology to gain an unfair advantage in business and life.
So far, so nonsensical, but the devotees to his Bulletproof Coffee are growing. In London, several cafés now stock the beverage, including Crussh, a branch of juice bars, which replaces milk with butter in its so-called Smart Coffee. The drink is prepared with coffee beans, two pats of butter from grass-fed cows and MCT oil (a coconut and palm kernel oil derivative). The standard price is £2.95; or for £3.65 you can add a dash of Bulletproof Brain Octane Oil.
This, Aga Mis, the manager of the Victoria branch tells me, is 15 times stronger than the regular brew. “We started doing it about four or five months ago. It is getting a lot more popular. It is the sort of drink that you develop a taste for. We sell about 10 a day.
Such concoctions, say the critics, encourage the worst in modern-day narcissism and will no sooner help you lose weight than a bacon butty. Incidentally, Asprey preaches an overall diet rich in saturated fat to be enjoyed alongside his coffee.
“There is no science that would back this up as a weight-loss tool,” says Dr Sally Norton, an NHS surgeon and leading UK weight-loss consultant. “The problem is we have a huge obesity epidemic where two thirds of us are overweight and one quarter obese. The more we try to lose weight, the worse it is getting. People are just desperate and don’t know where else to turn.”
Sian Porter, a spokeswoman for the British Dietetic Association, who first heard about fat blacks a few weeks ago, is similarly sceptical. “He has done one of the classic things that fad diets do by saying he has looked at thousands of studies. But it is about quality not quantity."
As for the taste of a buttery coffee, and the claim that the drink boosts “mental clarity”, who better to ask than the harried office workers of London walking the streets during a week of Christmas parties?
“All you can taste is the butter,” says Stuart Butcher, 40, who works in acquisitions and marketing. “Normally, I would just go for an americano, maybe with a bit of cold milk.”
Craig Timmis, a 33-year-old lawyer, decided to have a sip on his way back from lunch at a nearby Thai restaurant. “It tastes very weak, but there is a greasy film that definitely stays with you.”
“I love butter, I put it on everything, and I love coffee as well,” says Helena Kilduff, 26, an account manager. “But,” she says, regarding the droplets of oil formed on the surface, “definitely not the two together.”
In 2015, Asprey plans to open his first Bulletproof café in Los Angeles, but the people of Britain might take more convincing. Until then, viva the milk and two sugars, and save the butter for your toast.
This article was first published on Dec 18, 2014 and has been republished after researchers claimed that warnings against the consumption of butter should never have been introduced