Well, we're creatures of habit, and of associations, right? So regularly eating while reading the newspaper, for example, is a learned habit--or a conditioned response, re: Pavlov--that we've learned over time. Repeated "submission" to the urge to eat once we've opened the newspaper reinforces the association we have of Newspaper = Eat. In turn, if we can quit these habits for just a couple weeks, the associations weaken, so these automatic actions stop being automatic. This applies to all sorts of food associations we have--always eating at a certain time, for example, or in a certain place. And for the most part they can be kicked with simple diligence.
Of course this is a lot harder when the foods we're eating have emotional significance or have addictive properties. As a reformed sugar-addict, I understand that phenomenon all too well.