Stefanie Sacks of Montauk, a chef and nutritionist who has dished far and wide about how the food we eat affects our health — she has a weekly WPPB radio show, “Stirring the Pot,” does a weekly blog, “What the Fork,” and has contributed to three books on the subject, not to mention appearing recently on “The Dr. Oz Show” — has now put her sage advice and considerable knowledge into a new book, “What the Fork Are You Eating?” to be published next month by Tarcher/Penguin.