ranks wrote: ... It's as simple as coffee causes stress and stress causes weight gain long term as has been shown in recent studies.
An additional kinda' interesting theory I have read (still looking into it), involves the acidity of the coffee itself--plus more acidity from any added sweeteners or "whiteners"--and the body, which is designed to protect us as much as possible from our mistakes, layers "fat" to protect vital parts of the body from the destructive acids. It's proposed that when the acidity is removed (body pH balanced) , the fat is released by the body.