As a diagnosed Celiac sufferer, I am often asked to explain why I am not eating bread. When I do so, people often tell me something to the effect that they "couldn't live" without bread or some other wheat-based product. To which I often reply to the effect that if they had my symptoms, they'd never want to eat their beloved wheat-based food.
However, I think I may be very wrong about this.
Check out the 8 minute prologue to this episode of "This American Life", where people eat nuts knowing they'll be headed to the emergency room, or bring an epi-pen with them when they go out for a shellfish meal.
An ER doctor is quoted as saying "the ER is a virtual laboratory of dysfunctional behaviors and bad choices".
And that puts it into perspective for me at least. If some people spend a lifetime smoking or abusing alcohol or not dealing with their diabetes, of course there are going to be those who won't worry too much about poisoning themselves for a comforting meal.