When People Quit Smoking, Is Weight Gain Unavoidable?

Link: Is Weight Gain Unavoidable?.

There are a lot of people who smoke out there who, among other reasons, are afraid to try to quit smoking cigarettes for the fear of what they think is inevitable weight gain. Almost everyone they know who has successfully quit smoking really packed on the pounds and they don't want this to happen to them. So, does the connection between quitting cigarettes and weight gain have to do directly with the cigarettes themselves, or are there other, outside reasons why this happens so often to people who "kick the habit"?