Obesity occurs at 2-3 times the general population rate in persons living with a psychotic illness. The risk of obesity-related serious medical conditions like diabetes and heart disease are also two to three times higher in this population. Traditional behavioral weight management approaches help more than half of these individuals to lose weight, but a significant proportion are not helped. This pilot study is intended to determine the feasibility, efficacy, acceptability, and potential clinical utility of an intervention that integrates mindfulness, acceptance, distress tolerance, and motivation and commitment combined with traditional behavioral strategies for weight loss. This is the first study to investigate such an acceptance-based behavioral intervention for weight loss in psychotic illness. The results from this study will help to determine whether future research in this area is warranted with a larger sample, over a longer period of time.

Primary hypothesis: Weight loss will be greater in individuals who receive the acceptance based behavioral intervention, relative to those who receive nutritional counseling.

Inclusion Criteria:

• BMI > 25.0
• Diagnosed psychotic illness (i.e., schizophrenia, schizoaffective disorder, schizophreniform disorder, bipolar I disorder, major depressive disorder with psychotic features, substance-induced psychotic disorder, and psychotic disorder not otherwise specified).

Exclusion Criteria:

• Inability to provide informed consent
• Prediabetes or type 2 diabetes mellitus
• Current enrollment in another formal weight management program
• Brief Psychiatric Rating Scale (BPRS) ratings of 4 or more on any one of Grandiosity (Item #6), Suspiciousness (Item #7), Hallucinations (Item #8), Unusual Thought Content (Item #9), or Conceptual Disorganization (Item #10), or a BPRS total score of 80 or more.