Butter coffee: Will it give you extra energy -- or just make you fat?

Still sleepy after your third cup of coffee this morning? A new fad promises to give your daily cup of joe an extra kick of energy – while helping you lose weight – with the addition of a surprising ingredient: butter.

That’s the idea behind “Bulletproof coffee, ” a trend that’s gaining popularity among those who follow the “paleo” diet, a caveman-type eating style that means consuming mostly animal proteins and fats. Fans of the recipe say that adding a couple tablespoons of unsalted, grass-fed butter – plus a coconut-palm oil blend called MCT (medium chain triglycerides) – boosts your energy, promotes weight loss and revs up your brainpower.

It might sound like a wacky combination, but adding butter to coffee is an ancient tradition in some parts of the world. And when you remember that butter is very similar to cream, the idea makes sense.

A person would feel full after a cup of "butter coffee,” as a cup can contain about 100 to 200 calories, depending on how much butter is added. Most "recipes" recommend unsalted butter to produce a creamy version that enhances the taste of coffee and removes any bitterness.

But this elixir actually might promote weight gain if these calories are added daily. As for the energy boost claims in the "bulletproof" version of this drink, this is most likely a placebo and not generated from the butter/coffee blend, or the addition of MCT. The claim here is that MCT, because of its faster digestion compared to other fats, is an energy booster, but there is no evidence for any of this.

Bottom line: It won't harm you to consume it, but be mindful of the extra calories and don't expect weight loss or extra energy. If you enjoy this buttery concoction, great. But remember, when something sounds too good to be true -- it probably is.