There were a much of reasons posted quite a while ago, but I couldn't find them. I'd do recall that it effects blood sugar, increases insulin, and stimulates hunger.
I never quit, through, I just try to drink lots of water after.
I just got the talking to today about caffeine.. I still have one cup a day with sugar free creamer and she said it causes blood sugar spikes (the caffeine does) and also stimulates stress hormones which help to store fat.
I had 1 cup every day in the morning and then drank 1 or 2 cups of decaf during the day. I really don't mind decaf and the regular wasn't really a wake up for me as i had it after my workout and shower.