Dave Asprey does not like infomercials. He didn't want our conversation to feel like one, he said, raising both hands in a gesture of innocence, like a magician showing there was nothing up his sleeve. But once he planted the suggestion, it wouldn't go away. There was the register of his voice, oscillating between breathy and enthusiastic, and the complete absence of qualifiers to soften his bold claims. And then there were the wares clustered on the table in front of him. He had laid out cups of his signature product, Bulletproof Coffee, which is made with grass-fed butter and Brain Octane, a trademarked oil extracted from coconuts. Next to the cups lay Bulletproof-branded protein bars in chocolate and vanilla. ''I am not plugging my stuff,'' he said with a semi-embarrassed laugh. ''I'm just talking about how things work.''
And this is how things work for Asprey, according to his claims: By experimenting on his own body, he found a diet to end all diets, one that encourages the consumption of rich foods like avocado, steak and butter and requires little exercise to maintain a healthy weight. In the course of developing this diet — the Bulletproof Diet — Asprey says he lost 100 pounds, boosted his I.Q. more than a dozen points and lowered his biological age in the process.