Biologically, you don’t require animal protein to vanquish hunger—you need fiber, an indigestible carbohydrate. “Fiber sits in your gut until it goes down and out,” says Levin. “You’ll feel more full eating heavy fibrous foods like oatmeal or a bean burrito, and you’ll digest fewer calories overall. You should never feel hungry eating this way.” The PCRM recommends 40 grams of fiber per day, but most Americans eat only about 15 grams. To bridge the gap, work fiber into every meal—a cup of quinoa or rice at breakfast, a veggie or bean burger for lunch, and 2 cups of broccoli with dinner, for example. Bonus: A high-fiber diet may help you live longer, according to a recent study of more than 450,000 Europeans.