.Fat Chance

Is the butter-in-coffee fad really good for you?

Forget toast. We’ve already moved on. But don’t even think about taking away our butter. Fat fuels the brain, and who doesn’t want to keep their cognitive organ running smoothly under a well-oiled sheen? Yes, the fat revolution is upon us, and it sure feels liberating to reclaim the goodness of every naturally occurring fat short of whale blubber. But is the latest breakfast replacement trend—which calls for two glorious tablespoons of organic grass-fed butter—taking this fat love thing a little too far?

Dave Asprey, CEO and founder of Bulletproof(R) coffee, promises weight loss, a slower release of caffeine, and sustained, intense concentration and focus (like six hours’ worth) when you follow his recipe for the fast-spreading breakfast of champions—“upgraded” Bulletproof-branded coffee ($18.95 for 12 ounces of beans), an optional teaspoon of “Brain Octane” MCT (multi-chain triglyceride) oil—derived from coconut and palm kernel oils—and, of course, a super-sized hunk of butter.

Blend into a creamy froth, scandalously dotted with globules of pooling butter. Then drink it down, smack those lips a few times (they’ll be greasy) and head out the door. Just be careful not to fly too close to the sun and melt those buttery wings.

While there may be a tendril of truth to Asprey’s claims—and I do have a rather fit friend who calls the concoction a “game changer”—taking your coffee with an oil slick is not going to be good for just anybody. Aside from the 441-calorie mixture not being the most nutrient-filled way to start your day, it may (surprisingly) do more harm than good, depending on how your body works.

“He’s not giving you the full story physiologically, and what he’s leaving out is really important,” says Dr. Dawn Motyka of KUSP’s Ask Dr. Dawn. For instance: “You absolutely cannot have any starch or sugar with this.” And no matter how tempting it may be, Asprey really should warn his followers not to add sugar. “That would be horrible, because then that fat is just going to circulate in your arteries; you can’t burn it.”

But even if you follow the recipe without detour, you need to be careful. “If you do that for breakfast and then you have pasta for dinner you’re going to screw up your epigenetics,” she says. Epigenetics is the study of how genetic activity can be altered without changing genetic code.

She illustrates the fat versus carb epiphany with the “McDonald’s recipe for death”—high saturated fat and high carbs. “If you mix those two, the insulin from the high carbs steps on your body’s ability to use those fats as energy,” says Motyka. In other words, once you eat any starches or carbs at all, your body turns off fat burning for hours. “The problem is that it’s really hard to not eat starch and sugar in our society, and in combination with high fat, especially saturated animal fats, it can be very toxic for people.”

Also, worth knowing before you jump on the bulletproof bandwagon: the trend is really only OK for people who are on a strict paleo diet—for more than just that day.

“If you’re eating paleo, after a couple of weeks your body adjusts and you produce different enzymes, and your body starts to burn fat, and when you do that that’s great, but the adaptation relies on you not eating sugars,” says Motyka.

So, in order for the proposed benefits to outweigh the potential damage, your body needs to be in ketosis—burning ketones, water-soluble molecules produced by the liver from fatty acids—rather than glycolysis, when your body is burning glucose for fuel.

I promised a tendril of truth: Mental performance is very likely to be at its best when you’re in that euphoric fat-burning state. “Because you’re in ketosis, when your brain is fed fat and is burning fat as fuel, it does alter your concentration, which is why people fast before exams,” says Motyka, who used to fast before her exams in med school. “Burning fat as fuel, because of the ketones, changes things in the brain. So he’s right about that.” And then she empties one last bullet: “But any starch will blow that.”