The purpose of the proposed study is to develop and pilot test a manual-based, interdisciplinary intervention for youth, ages 3 to 10 years, with autism spectrum disorder (ASD) and overweight called the Changing Health in Autism through Nutrition, Getting fit, and Expanding variety (CHANGE) obesity program.

The purpose of the study is to develop and test the feasibility of a structured, innovative approach to treat obesity in 16 children (age 3 to 10 years) with autism spectrum disorder (ASD). This 16-week program integrates behavioral psychology and nutrition science to meet the challenges of obesity in children with autism spectrum disorder (ASD). The PI will apply an evidence-based behavioral intervention to increase food variety,15 use applied behavior analytic strategies to teach physical activities in a developmentally-appropriate manner, employ biometrics to assess progress, utilize dietetic interventions to improve nutritional balance, and train caregivers to use behavior management strategies.

Inclusion Criteria:

• A diagnosis of ASD confirmed by a clinical psychologist using a "gold standard" diagnostic tools
• Overweight status, as evidenced by a BMI percentile > 85% to 94%, and 4) mild to no food selectivity, as evidenced by either history of consuming some fruits and vegetable, tolerating new foods near their plate, and/or trying new foods

Exclusion Criteria:

• Children being treated with atypical antipsychotics (e.g., olanzapine, aripiprazole, risperidone) or other medications known to cause weight gain will be excluded from the study due to the weight gain associated with these medications
• Children with unstable medical conditions will be excluded for safety concerns
• Children presenting with severe aggression, self injury, or other disruptive behaviors that require intensive behavioral intervention will be excluded and referred to other services as needed