Awesome answer, Chris. I don't understand why it bothers his/her conscience to fast or not to fast on the Sabbath. That's why I told her to ask God for direction. With sincere fasting and prayer I'm almost sure she would get an answer on it. It is way above me. Generally speaking, I think following your conscience is a good thing.
This sounds like he/she has been brainwashed by the teachings of man.