I´m on a Paleo Diet for about 2 months now, and I´m pretty strict with myself, except when I go out partying. I ususally go out once in a week. In the Paleo Process I lost about 12 pounds, which was my goal since I was relatively lean to begin with, but those extra pounds where wonderful to loose. So it´s not about the weight gain when I drink, but about Diarrhea which I sometimes get from drinking. I usually drink Red Wine, Gin Tonic, shots or Vodka Mate (A cold soda-like drink with extra coffeine that´s made from Mate tea, with a vodka shot) and the Diarrhea sometimes starts at the evening itself or the next morning.
With Vodka Mate, it´s the worst really, I wonder where that comes from, maybe the sugar? (I usually just get a "higher (still low) amount of sugar from a few berrys thrown in my greek yoghurt) Maybe there´s something that one can eat before going out? As mentioned, I eat pretty strict, but I don´t want to give up a occasional Gin Tonic at a Party, because I like it :)