Through Oxford Learner's dictionaries, I could find the meaning,
to avoid eating, drinking or smoking something
So I made a sentence to the effect that "I always keep off snacks or beverages" in an English class but a foreign teather advised me that I'd better use just "avoid" rather than "keep off" because I can't know the proper context that such specific phrasal verb is natural.
So these days, is that use of "keep off" weird? Actually there was no specific context. I just had to make any sentence.
But if I assume a specific context, like when I am asked about my efforts to keep up my health, I'd answer like that. Would it be weird?