Ultra-processed food makes up 60 percent of the American diet. Though to call it food is a stretch. Because it is not, strictly speaking, food at all. It is an industrially produced edible substance. And it’s killing us. That is the nauseating conclusion Chris van Tulleken reaches in his new book, “Ultra-Processed People: The Science Behind Food That Isn’t Food.” Today, he explains how big businesses have corrupted our diets and what we can do to stop them from causing further harm.