While there is a high rate of comorbidity between EDs and OCD, there is limited research on how to treat this comorbidity. Evidence-based treatments for EDs share many core tenets, though it is unclear which treatment features are necessary. CBT-E and FBT both focus on maintenance mechanisms, alliance building and providing a strong rationale for change. For underweight patients, they target weight gain and use in-session, collaborative weighing and weight graphs to document progress. Both focus on dietary restraint and restriction early on, and FBT indirectly and CBT-E directly target body checking, body avoidance, and social comparison behaviors. Both treatments prepare for relapse prevention and termination. There are similarities between the treatments for OCD and EDs, such as focusing on session agendas, providing structure and expectations for treatment, psychoeducation, a collaborative therapeutic relationship, and self-monitoring. CBT-E uses hierarchies and targets body checking and body avoidance similar to therapy for OCD. Both CBT-E and OCD treatments include elements of cognitive therapy, using corrective learning and behavioral experiments.

The introductory chapter defines pseudoscience as it relates to therapy. Potential harms of using pseudoscientific interventions are discussed. Pseudoscience is contrasted with attempts to identify science-based therapies. The chapter identifies the challenge in distinguishing between science and pseudoscience due to the fuzzy boundary between these two constructs.