I completely get what you mean. I have to forcibly isolate myself from my work "lunch" buddies and my friends when i am fasting. It is never easy explaining the concept of a Water Fast to someone without them getting all weird about it, and accusing you of hurting your body or starving yourself (so I just avoid that discussion all together- which makes me kind of a wuss).
The drinking thing stinks too, not that i am a heavy drinker, but it seems I always pick the worst time to fast and i miss birthday parties etc where the plan is to go out drinking.
It is a pain, but after 2 weeks of politely ducking out... they stop asking- which is nice.