I get no warning really. I usually wake up dreading the phone calls i'll get from friends from the night before telling me all the stupid crap I did. It's like i'm fine at a six pack, and as soon as I pass that point i'm a black out drinker. Anything over five or six and I forget usually the last hour or so of the night, and of course that last hour would be the hour I need to remember so I can make proper apologies. 😉 Lately I have not been drinking at all because of this, and this was the reason I stopped drinking for 8 years(22-30), and only started again two years ago after a breakup. It sucks, because when I go out I have to be really carefull not to have any more than like five beers, forget about mixed drinks. I'm a light weight I guess. BTW, I weight about 185lbs.