The studies talk about alcohol not contributing to weight gain. I assume this would basically mean something like, e.g. 80 proof liquor, where your just getting alcohol and water. So, if the studies are correct, it would indicate that drinking shots of vodka straight, or mixed with soda water or diet soda would not contribute to weight gain. On the other hand beer has all of the fermentables along with the alcohol (i.e. the carbs). So beer could be a different animal altogether. For beer, I'd suggest Guinness draught (not extra stout or foreign extra stout). The draught is only supposed to be 110 kcal per 12 oz., which is comparable to a light beer. I usually try to have a guinness draught, or maybe a black & tan made with it.