Started out at 130lbs saying I would just gain a few to see how it felt. 2 years and 70lbs later I have to say I can't stop thinking of growing even bigger!
I also thought I was addicted to gaining weight. When I was 75 kg, I said 100 kg at most. At 105 kg, I wanted 115 kg. Then the maximum weight was 120 kg and now at 122 kg I'm thinking about 130 kg +. I like being bigger and I give in to it.
once you get that far into it, there's no pulling out. you might succeed in losing weight through diet and exercise for a while, but you'll go back to gaining, eventually. once the program is installed, it can't be uninstalled.