(Bulletproof Coffee is bringing a ready-to-drink version of its high-fat drink to Whole Foods stores nationwide this fall.Facebook/Bulletproof)

• Bulletproof Coffee, a "biohacking" wellness brand, is bringing a bottled version of buttered coffee to market.

• The ready-to-drink product will roll out to over 400 Whole Foods stores nationwide this fall.

• The drink taps into a Silicon Valley diet craze that has techies eating lots of fat.

This past week, I swapped my usual coffee order — unsweetened with cream — for a buttered alternative that promised to give me mental superpowers.

In September, wellness brand Bulletproof Coffee launched a ready-to-drink version of its famous buttered coffee drink. The high-fat beverage will arrive in more than 400 Whole Foods stores nationwide this fall.

Made with cold-brew coffee, grass-fed butter, and a proprietary "Brain Octane" oil derived from coconuts, Bulletproof Coffee claims to diminish brain fog and increase mental function and energy, in addition to delivering a caffeine jolt. The beverage has amassed a cult following despite little evidence it works.

(Bulletproof Coffee comes in four flavors: Original, Vanilla, Mocha, and with collagen protein.Bulletproof Coffee)

An increasing number of Americans are filling up on fat in an attempt to live longer and better. A high-fat diet (also known as the ketogenic or "keto" diet in its extreme form) has been shown to promote weight loss, dull hunger, and stave off age-related diseases. It's catching on in Silicon Valley, where tech workers often claim the pro-butter diet gives them a mental edge.

Earlier this year, I tried the keto diet for two months. After nearly a month of restricting my carbohydrate intake, I experienced increased energy and focus. I also lost weight.

Bulletproof Coffee has sold the ingredients needed to make buttered coffee separately for years, but the new carton format makes it more accessible for the company's many skeptics. When I first heard about it, I hoped the drink would help me tap into the benefits of a keto diet.

Every morning this past week, I gave up Starbucks for a bottle of Bulletproof Coffee.

Bulletproof Coffee comes in four flavors: Original, Vanilla, Mocha, and Original with collagen protein. I expected it to taste like a creamy, indulgent coffee drink, but they tasted more watered down. The butter added a floral note to the aroma and made it more silky in texture.

The company behind Bulletproof Coffee, which is led by "biohacking" guru Dave Asprey, markets the drink like it's a shortcut to a keto lifestyle.