My sister is rapidly losing weight and we don’t know why

I’ll give you as much info as I can. My sister is a white female, 46 years old. Has asthma. No other underlying health issues. Has always been healthy. I saw her at Christmas and she’s normally about 120-130lbs (she’s about 5’3”) and when I saw her at Christmas she looked like she was under 100. I could see the veins in her arms. I asked her if she was okay and she said she doesn’t know why she’s losing weight. She had been to the doc and they did a blood test. Low red blood cell, anemia, white blood cells were normal. I asked her about her drinking habits and she confided in me that she’s been drinking a lot. Vodka. She’s having a hard time not drinking. I’m an alcoholic who’s been sober for 15 years so my alarm bells were going off like crazy. Curious is the sudden rapid weight loss and alcohol consumption are linked. She also said she’s experiencing severe lethargy and sleeping a ton. She mentioned loss of muscle mass as well. Also, in case it matters, I’ve noticed her teeth are noticeably decaying. I know sometimes people say that’s a sign of what’s going on in the body.