How can a new Muslim woman conceal her fasting in student housing?

Congratulate your sister on her embracing Islam, and advise her to leave places where Allah is disobeyed, given that she studies and lives in mixed environments. This carries sin and danger to her faith. Muslim sisters should explain to her the ruling on this and its danger to her, and that she must leave such places if she is able and if doing so does not lead to something worse. It is not permissible for her to take foreign men as friends, nor for him to take women as friends, as the relationship between women and men is governed by Islamic Sharia. As for her fasting, she must fast, and it is not permissible for her to break her fast. She can give the impression to people that she is not fasting by carrying a juice bottle and pretending to drink from it, or by saying she is ill and meaning psychological illness, or similar permissible stratagems.