Bulletproof Coffee

Bulletproof Coffee is black coffee blended with a spoonful or two of unsalted butter and a spoonful or two of MCT oil (a refined coconut-derived fat). Blending, rather than stirring, emulsifies the fat into the coffee so it turns pale, frothy and creamy – it looks a little like a latte but contains no milk.

The name is a brand: “Bulletproof” is the company founded by American entrepreneur Dave Asprey, who popularised the recipe. In general use it’s also called butter or keto coffee. It’s typically drunk instead of breakfast by people following low-carb, ketogenic or intermittent-fasting diets, who value the feeling of fullness the fat provides.

Be aware of what’s in it: a full-strength cup contains several hundred calories, mostly from saturated fat. Claims that it boosts brainpower or helps weight loss are not supported by scientific evidence; dietitians put the extra alertness down to the caffeine.

Dave Asprey, an American tech entrepreneur, said he got the idea after drinking yak-butter tea while trekking in Tibet in the mid-2000s. Back in the US he experimented with butter in tea and coffee and published his “Bulletproof” recipe on his blog – usually dated to 2009, though some accounts say 2010.

The recipe spread through online biohacking and low-carb communities, and Asprey went on to found the Bulletproof company in 2013 and publish The Bulletproof Diet in 2014, selling coffee beans and MCT oil branded “Brain Octane”. Mentions by celebrities on American television helped turn it into a mainstream trend.

The drink has drawn criticism from dietitians: the claims that it improves cognition or aids weight loss lack scientific support, and the British Dietetic Association has listed the Bulletproof Diet among fad diets. Adding butter to hot drinks is far older than the brand, however – from Tibetan butter tea to buttered coffee in Singapore.