Should you exercise when recovering anorexia?

hi, so im 16year old girl 5ft 2 and weight 82-85lbs, im curious, should i exercise while recovering? (yes, i truly am trying to recover) My nutritionist says to be careful, but why? wouldn't i just gain like fifty lbs??? i dont want to not exercise! is it ok to exercise? like 30min? shouldn't i do that to boost my metabolism? do you know? please answer! please no crap.