I've quit smoking, or fasted as you might say, many times in fact
And sure, I do think it is good for you, sort of lessens the pull of the ally and can give you brief glimpses of clarity, but let's be honest with ourselves... It's really not that big of a deal. How about an actual fast for seven days, or go a few days without salt, or perhaps a month without talking, how about a few years without a phone, or tv, or internet.. There are a lot of things we can do without that can help in or journey to understand ourselves, but it's always important to ask yourself why...
Fasting, abstaining, withdrawing or whatever you want to call it forces you to look at the connections you have with things and evaluate the emotional energy that you have invested in them. And I do think that is a healthy and worthwhile experience to have, but again there needs to be a reason for it all... What is the objective here, or intent..? If it's to know yourself and all you are willing to do for that is take some ayahuasca and fast from tobacco you might not like what you see so much.
Fortunately there are other ways of getting to that knowledge. They require a great deal more work, dedication and persistence, but when you get there the experience is your own and the knowledge gained is yours forever.