A Lifestyle Intervention to Reduce Cardiometabolic Risk Factors in Individuals With Obsessive-compulsive Disorder

Inclusion criteria: 1. A diagnosis of obsessive-compulsive disorder (OCD), based on the diagnostic criteria of the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders. Screened at registration and at the initial phone call and confirmed by the assessor at the inclusion assessment (psychiatric interview), using a semi-structured diagnostic interview. 2. Physical inactivity/sedentarism, operationalized as less than 150 minutes of physical activity per week during the last month, evaluated by asking two questions from the Swedish National Board of Health and Welfare concerning 1) frequency of weekly moderate or vigorous intensity physical exercise and 2) frequency of weekly non-exercise/daily life physical activity. Screened at registration and at the initial phone call and confirmed by the assessor at the inclusion assessment (psychiatric interview). 3. Aged 18 years or older. Screened at registration and confirmed by the assessor at the initial phone call and/or confirmed by the assessor at the inclusion assessment (psychiatric interview). Exclusion criteria: 1. Intellectual disability or severe psychiatric symptoms or suicidal risk that could interfere with the intervention. Screened at the initial phone call and confirmed by the assessor at the inclusion assessment (psychiatric interview), using a semi-structured diagnostic interview. 2. A diagnosis of an eating disorder or a substance use disorder. Screened at the initial phone call and confirmed by the assessor at the inclusion assessment (psychiatric interview), using a semi-structured diagnostic interview. 3. Being pregnant or \<1 year postpartum. Screened at the initial phone call and confirmed by the assessor at the inclusion assessment (psychiatric interview). 4. Myocardial infarction or stroke within the last 6 months. Screened at registration and confirmed by the assessor at the initial phone call and/or the inclusion assessment (physiological measures). 5. Cardiovascular risk measures significantly over the normal range (e.g., severe hypertension \[blood pressure above ≥180 mmHg systolic or ≥110 mmHg diastolic\]) or a current somatic condition that make participation in the intervention contraindicated. Screened at registration and confirmed by the assessor at the initial phone call and/or the inclusion assessment (physiological measures), after consulting with the study doctor, if necessary. 6. Initiation or adjustment of any cardiometabolic medication (e.g., blood pressure or blood lipids lowering mediation) within 3 months prior to assessments. Screened at registration and confirmed by the assessor at the initial phone call and/or the inclusion assessment (physiological measures). 7. Inability to understand and communicate in Swedish. Confirmed by the assessor at the initial phone call. 8. Inability to consistently attend the sessions involved in the intervention. Screened by the assessor at the initial phone call and/or confirmed by the assessor at the inclusion assessment (psychiatric interview). 9. Inability to travel to the sessions involved in the intervention. Screened by the assessor at the initial phone call and/or confirmed by the assessor at the inclusion assessment (psychiatric interview).