"In his midtwenties, Dave Asprey was a successful Silicon Valley multimillionaire. He also weighed 300 pounds, despite the fact that he was doing what doctors recommended: eating 1,800 calories a day and working out 90 minutes a day, six times a week. When his excess fat started causing brain fog and food cravings sapped his energy and willpower, Asprey turned to the same hacking techniques that made his fortune to "hack" his own biology, investing...