I don't think you have to say anything at any time to anyone unless you want to.
He can make all the assumptions he wants. He most likely is not going to ask something like, "Hey, I noticed you're eating more cookies, is that because you're an alcoholic?"
Even in the unlikely event that he says anything, what's wrong with saying, "I felt a little unsteady and was hoping sugar would help."
Seriously, he's not going to quiz you. If he does, just don't talk about it. Shrug and be quiet.