When Jimmy Fallon recently gave actress Shailene Woodley a mug of coffee blended with butter on “The Tonight Show,” she raved to the audience about the cup of saturated fat: “It will change your life!”
 

“It’s the most delicious thing ever,” Fallon said. “But it’s actually good for you. It’s good for your brain.”
 

As the exchange highlights, “bulletproof coffee” — a creation of the technology entrepreneur Dave Asprey — is all the rage, but has many health experts worried that it doesn’t deliver on its promises of better health, The New York Times reports. 

The recipe — a take on the yak butter tea Asprey found restorative while hiking in Tibet — calls for low-mold coffee beans; at least two tablespoons of unsalted butter; and one to two tablespoons of medium-chain triglyceride (MCT) oil, a type of digestible fat.
 

Asprey claims the 450-plus-calorie cup of coffee for breakfast suppresses hunger, promotes weight loss, and provides mental clarity.
 

“It’s a gateway drug for taking control of your own biology,” Asprey told the Times.

But Joan Salge Blake, a clinical associate professor of nutrition at Boston University, is one of many skeptics, noting that it’s carbohydrates, absent from the drink, that are brain food.
 

“This is not a breakfast of champions,” she said.