Does alcohol withdrawal cause loss of appetite?

It can. Or it could be an alcohol-related illness like liver disease or gastritis.
Yes. Decreased appetite, insomnia and anxiety are all common symptoms of alcohol withdrawal. If this is you we are talking about, it is important for you to get yourself into a support system to stay quit, as well as taking a multivitamin and thiamine (vit b1 at least 50 mg daily), especially if you are not eating properly. See your doctor for a health evaluation and additional support.