Our body is not good at regenerating tissue. Doing anything that can actually harm that tissue is probably pretty permeant. Sure, long-term overeating may be bad for you, but it's not likely to permanently hurt you.
When you look at tobacco, congress is pretty much making it as illegal as possible. They tax it a lot, plaster the containers with warnings, etc. I think right now they are focused on getting as few possible people to use it before they make it illegal.