Detox, health kick, medication, weight loss.
Chances are no one will ask why you're not drinking, or only mention it in passing. If you don't draw attention to it or make a thing out of it, chances are no one else will. I only had one person ask me about not drinking. I had a huge fear about what to say when people asked me, but no one really did. Only people with drinking problems pressure others to drink. Normal drinkers don't care if you drink or not.
You could always decline invitations to drinking things for a while. "Love to come, but can't make it." No excuses needed.
I've had to move away from a few friends who drink a lot. I have no idea if they are alcoholics, but I just know they aren't good friendships for me to be in because they revolve around drinking.