I've noticed the same thing. And like dgillz said, only a physician could say if its "end stage" but it is certainly a physical manifestation of the progression of alcoholism. When alcohol consumption is increased, the body mistakenly treats empty calories as nutrition...shutting down the body's hunger response. I suppose if you couple that with the complete lack of movement required from going on a five day bender and only getting out of bed to drink, use the restroom and smoke...you are going to lose a lot of muscle tone (I speak only from my personal experience and observations)
I recently gave the A in my life a hug and just felt a little disturbed. Not a whole lot of substance there anymore - just skin and bones. I've also noticed some clubbing of his nails...another physical manifestation of the disease.
Sad.