If i told counsellor that i have eating problem would he tell anyone or talk about it in sessions would he involve anyone else. i want to open up. ?

Good Idea : It is a good idea to open up and tell all the problems you have including any eating problem.If it is one to one session, it is confidential and your counsellor will keep it confidential. But if it is a group session where every case is discussed, then the other people in group will know your problem as others may have similar problems.

Against Med. ethics: Your counsellor, as long as they are certified and part if an established health facility, or entity, are bound to keep your personal information confidential, esp. things that you tell them in confidence. In some situation, they can group people with similar issues mainly for teaching purposes where they can discuss and learn from each other.