Once the alcohol is out of your system, you will go back to using fat. Ketosis is maintained the entire time (ketones from alcohol, then ketones from body and dietary fat).

The only thing I wonder about is whether or not is best to limit your food consumption. I've read that if you plan on drinking, its best to eat something high in protein, as that it will help limit the amount of fat storage. However, as far as I can see, anything you eat that is not used for fuel, has potential to be stored as fat.

Its probably very unhealthy advice to say "while drinking, don't eat anything", but I know it won't kill you as long as you only do it once in a while.

Here's an intesting question: if you eat a bunch of carbs while drinking (such as drinking 12 beers at 6gm carbs each), can you kick yourself out of ketosis? This is a topic I'm very concerned with myself.