I believe in being honest about this everywhere but at work.
Work is different.
You have an established drinking relationship with him. He will obviously take note of the change if you simply say youre not drinking. That might make him really uneasy around you.
He's not a close friend, he's a boss. Tell him what will make both of you comfortable. I like pakman's liver numbers idea, makes you look kinda tough and proactive at the same time.