As nutrition professionals in areas of body weight regulation, psychiatry, and neuropsychiatry, we commonly evaluate and treat complex nutrition challenges among youth with autism spectrum disorder (ASD) and/or intellectual and developmental disabilities (IDD), including patients with comorbid psychiatric diagnoses. Our presentation addresses the risks of malnutrition, obesity, and micronutrient deficiencies within a framework of common eating behaviors, feeding challenges, and specialty diets utilized in youth with ASD/IDD. With this in mind, we describe the formulation of inpatient and outpatient nutrition treatment strategies for youth with ASD/IDD across the BMI spectrum and include case studies to demonstrate interdisciplinary implementation. Dietitians will learn how to overcome behavioral and systemic barriers to ensure equitable health outcomes for this patient population during the current pediatric mental health crisis.