The Secret to outsmarting restaurant calories, much on food before leaving to eat out. It's easy to overindulge when the size of the main course at your favorite restaurant is triple what you'd normally dish out at home. To keep from eating more than you truly want, munch on an apple before you leave the house. Apples are rich in pectin, a soluble fiber that slows the digestive process, so you'll feel full on less food. The result: you'll eat just enough to make you happy- and even have leftovers to bring home.