Are nutritional counseling for eating disorders helpful?

Yes. In my experience with patients with eating disorders it is essential to have both a counselor to help deal with the control issues and a nutritionist with experience specifically in eating disorders. So yes yes yes such counseling is helpful.
Yes. Effective treatment for eating disorders often requires a team approach and nutrition counseling is an essential component of this. A nutrition professional can help create individualized diet plans that meet one's physical & emotional needs & take into account one's motivation & capabilities. A registered dietitian who specializes in eating disorders could offer these services.
Yes, but........ Eating disorders are normally not related to lack of knowledge of proper nutrition. Quite the opposite, from my experience, they are obsessed with how, what, when to eat. Both anorexics and bulimics have lost the "physiologic feelings of satiety" they feel clueless, and helpless when it comes to the process of eating. The normal messages to their brain and gut seem to be "turned off" . More....