A purposive sample of participants with atrial fibrillation and overweight defined as BMI>27kg/m2 was recruited from the outpatient department of a large hospital in southern England.  Qualitative data was collected via semi-structured interviews conducted by telephone. Participants began by completing two Quality of Life questionnaires (Atrial Fibrillation Severity Scale and EQ-5D-5L using a ThinkAloud technique. The COM-B (Capability-Opportunity-Motivation) behaviour change model was used as a guide for the semi-structured interviews.