For most people it takes a while for our bodies to remember how to process actual food instead of just breaking down alcohol toxin as fast as possible. Many organs involved in metabolism are clobbered by alcohol...liver, pancreas, thyroid, intestines...and it takes time to heal.
I lost maybe five pounds on a permanent basis the first few months but I was pretty close to what I should weigh for my height and bone structure. Another way to look at it is that I haven't gained weight that I would have for sure had I kept on drinking.