In this exclusive preview of Gary Taubes’ new book, Taubes explains why most of us have a fraught relationship with food and a flawed understanding of what makes a healthy diet. “‘Is it safe?’ is always one of two ultimate questions when considering a change of diet or lifestyle, particularly with the goal of preventing chronic disease,” Taubes writes. Is a ketogenic diet safe? Is a plant-based diet safe? Is saturated fat dangerous? Here Taubes evaluates the various methods we have for answering these questions, from personal experience and anecdotal evidence to clinical trials.