Weight Gain in Family-Based Treatment for Avoidant/Restrictive Food Intake Disorder (ARFID) with and Without Autism.

Health-threatening underweight and poor growth is a frequent consequence of Avoidant restrictive food intake disorder (ARFID) and should be a priority for treatment in children and adolescents (young people, YP). Coexisting autism is more prevalent in YP with ARFID than in YP with other eating disorders. Treatment studies are still sparse for ARFID, and it is not known whether treatment response is lower in those with coexisting autism, as it is documented in other eating disorders. In this study we examined if family-based treatment for ARFID (FBT-ARFID) was associated with weight gain in underweight young people (YP) with ARFID and if coexisting autism affected weight gain. A clinical naturalistic prospective case series of 33 YP aged 6.3-18 years with ARFID presentations and underweight were offered a manualized FBT-ARFID with weight monitoring. We examined changes in body weight between start and end of treatment in those with and without diagnosed coexisting autism. The majority of participants (N = 26, 79%) had a weight gain between 1 and 15 kg, whereas 7 YP (21%) had a stable body weight between start and end of treatment (differences between - 0.6 kg and + 0.9 kg). At the group level, weight gain was statistically significant between start and end (Median = 3.9 kg (4.0, -0.6 -15.1) z = 4.491, p <.001). There was no significant difference in weight gain between participants with (N = 14, 42%) and without (N = 19, 58%) coexisting autism. Participants had a significant weight gain at the group level, suggesting that FBT-ARFID is associated with weight gain in the majority of underweight ARFID patients, both with and without coexisting autism. However, a subgroup may need additional interventions in order to secure weight rehabilitation.