Some components of commonly used, empirically supported eating disorder treatments (CBT-E and FBT) may not be suitable for patients who also have OCD. These include aspects of parental control in FBT, collaborative weighing, self-monitoring and eating schedules/meal plans, and psychoeducation about food and weight. Achieving weight gain is particularly difficult in anorexia nervosa due to fear and preoccupation with weight, eating and “becoming fat.” Low body weight and malnourishment tends to increase anxiety and obsessionality, so weight gain early on is paramount, especially for individuals with this co-occurring presentation. Through clinical observations, patients have reported that FBT may aggravate OCD symptoms, such as preoccupation with numbers and exactness, and expanding obsessionality to concerns about exercise/movement and other topics within the morality domain of OCD. The lack of control and greater uncertainty that an adolescent experiences while completing FBT may be related to increased OCD symptomatology and poor treatment outcomes.