Women with bulimia nervosa and binge eating disorder often suffer for many years before they seek professional help. Evidence-based treatments like cognitive–behavioural therapy (CBT) might be poorly accessible, and about 50% of those who receive CBT respond to it. Such outcome may reflect the heterogeneous nature of eating disorders, and addressing this heterogeneity calls for expanding the portfolio of treatment options. In particular, it is important to explore such options’ acceptability, tolerability and affordability expressed through experiences with the treatment. This protocol outlines the rationale and design of a qualitative study. It captures experiences from patients and therapists who were involved in a randomised controlled trial (RCT) exploring the efficacy of a new group-based treatment programme combining physical exercise and dietary therapy. Open Access Article