A recent paper in the professional journal titled Appetite (how appropriately named!) reports that fasting for 24 hours improves nasal chemosensory performance (meaning improves the sense of smell) and food palatability (meaning makes you eat more than usual and enjoy it as well). In other words, changes in smell function can modify feeding behaviour.

— Read more at Why the smell of food makes you hungrier at The Hindu. You can find the original study at PubMed. The Shangri-La Diet involves clipping your nose while eating, and other methods of consuming "flavorless" calories; the Freakonomics blog has a number of articles on the subject.