I only lost about 10 pounds when I quit drinking, but that's a lot on my small frame. And I'm thinking that's just because I started living healthier as well, not because the alcohol caused me to put on a lot of weight.
I think that, due to my pattern of drinking, alcohol didn't cause me to gain weight excessively. I mainly drank hard liquor, and I drank a lot of it at a time, which causes the body to absorb less of the calories in total (or so I've heard).