Counsellor wants to tell my parents?

I have been seeing my counsellor now for a few months due to being diagnosed with anorexia, my counsellor is at college. I have tried my best to keep my feelings to myself and my parents now think everything is fine and I am alright, but my counsellor knows differently, I have lost more weight and my counsellor wants to weigh me tomorrow and talk to my parents :/ what should I do?