I used to smoke about three times a day for about three months, then I stopped suddenly. I lost 5 pounds, and I couldnt sleep for a week, even though I wasnt craving it "psychologically", as in missing the feeling of the high. I only smoke two or three times a week these days, and only in the evenings. Now I notice that if I stop for any reason, I dont get any horrible withdrawal symptoms. This is just my personal experience, but I believe pot can be physically addictive, just like nicotine.