There is no magic pill. There is no perfect diet. Could it be that our underlying assumption—that what we’re eating is making us fat and sick—is just plain wrong? To address the rapid rise of “lifestyle diseases” like diabetes and heart disease, scientists have conducted a whopping 500,000 studies of diet and another 300,000 of obesity. Journalists have written close to 250 million news articles combined about these topics. Yet nothing seems to halt the epidemic. Anastacia Marx de Salcedo’s Eat Like a Pig, Run Like a Horse looks not just to data-driven science,...