To me that sounds wise. I wouldn't want to add anything to a fast myself, especially not caffeine. You can't sleep, apart from anything else! Well, the first cup of tea or coffee I have after a fast- I don't sleep that night, so I'd assume it'd be the same during a fast, maybe worse.
Good luck with your fast and your goals. I fasted to break a nicoteen/alcohol addiction last year. I'll tell you something, it gives you a BAD detox taste in your mouth for the first few days. My mouth felt like the inside of a train driver's glove! After I got past that, I was glad to be free of the cigarettes.
I smoked for over twenty years- all my adult life- so it's weird to be without them. When I am near someone who smokes now, I can really smell them, they really stink. I think "God, I used to be like that". You maybe had something similar during the months when you had quit.