When discussing "evidence-based" and the tug of war over one theory over another it is easy to lose sight of the point: effectiveness. What direction is likely to help more people do better faster?
Here's a beautiful description:
Family Based Therapy for anorexia: excellent outcomes
"Dr. Ellen Davis, cofounder of Woodland Forge in Phoenixville, Pa., is a strong advocate for FBT. “I used to practice traditional psychotherapy with patients with anorexia,” she says, “The recovery time for most adolescents was between 2-3 years. It’s much quicker with FBT. With a younger adolescent I can move them to the point where a parent will say ‘I have my kid back’ in 9-10 months. It’s an amazing approach.”
(Though I would quibble with the bits about the "the psychological, environmental or family issues that contributed to the eating disorder" That is not part of the approach as I understand it, and that kind of wording leads back down the rabbit hole of blame and shame. A given family may have to make changes to support recovery, but not all, and just having an eating disorder diagnosis doesn't mean there was any other reason or issue or problem - usually, an eating disorder is just an eating disorder.)