You don't need to quit drinking on the weekends. Just avoid a few pitfalls. Drink a hard liquor (Jack, Bacardi) with some diet coke. Theres next to no calories or sugar in that. If your going to drink beer, go for a light beer rather than something thick like Sam Adams or Sierra Nevada.
The problems with drinking (for me at least) come when you over do it and get completely hammered. This leads to several things:
1) You get drunk and start drinking anything in sight...thick beer, sugary mixed drinks etc.
2) You get wasted and at the end of the night your starving and the only place open is a Taco Bell or Wendys. Lets face it, brown rice and chicken don't sound too appealing at 2 a.m. when your drunk.
3) You wake up so hung-over that yo don't end up eating till late afternoon/early evening because you feel sick. When yo do finally muster up the courage to eat, it ends up being some greasy crap because, once again, healthy food is the last thing you want to touch when your drunk or hung over.
Just use some common sense and try not to over do it. If you do over do it, slam a shitload of water before you go to bed and pop a couple aspirins ahead of time. When you wake up in the morning, force yourself to choke down something, whether it be a few glasses of milk, a granola bar, anything.