I thought I was addicted to caffeine, I drank loads of coke and and coffee. Then I got a kidney stone (when I was 21, that was... er... next year, right!?). I didn't give it all up like I should have, but when I gave up coke I felt like crap for 3 days. I've been drinking coffee still for the last 10 years or so, but I gave it up 4 weeks ago. It was then that I discovered caffeine has no effect on me (save sending me to sleep), but I'm actually a sugar addict. After I gave up coke I ended up having my coffee white with 3 + cadbury drinking chocolate.
Alas, I am losing weight much faster without both