Bulletproof Coffee’s Dave Asprey: why healthy eating and exercise aren’t enough

The tech entrepreneur was once overweight and unfocused. Now his ‘brain‑boosting’ diet has made him the toast of Silicon ValleyDave Asprey, 43, is best known for his concoction Bulletproof Coffee, the go-to caffeine kick of Silicon Valley, Hollywood and David Beckham. A Guinness-dense combination of coffee, two tablespoons of butter and a product he markets called Brain Octane Oil, a triglyceride oil derived from coconut oil, the recipe was inspired by Tibetan yak-butter tea. B