The future perfect continuous is not needed in your example at all. That said, since you acknowledged it might sound awkward or not natural, I presume you just want an example of the tense being used in the same context you provided: "By this time tomorrow, I will have been refraining from consuming alcohol for a year."

That's a very good sentence in English and I fully understood it on first reading. I might say, "since I stopped drinking" instead of, "since I stopped taking alcohol." You don't really, "take alcohol" but, "drink alcohol" or, "consume alcohol." Another way of writing the sentence would be to say, "Tomorrow is my first/on-year anniversary of not drinking." "As of tomorrow, I won't have drank any alcohol for a year." Your sentence is (I believe) grammatically correct.

but I've just got flabbergaster I would say - I have just been flabergasted Tomorrow it will be a year since I stopped drinking (possibly "using") alcohol In Spanish they say "tomo (tomar - to take) una cervesa" Whereas in USA I would say - I drink a beer either way Cheers! Salud! Nostrovia

Hello, Your sentence is grammatically correct, it does not need the future perfect continuous. I hope this answers your question. If you’d like to practice speaking. I’d be happy to help you develop a study plan. Feel free to view my teaching profile and class offerings and send me a message if you think I can help you. Regards.