Experiences of people in specialist mental healthcare participating in a multidomain lifestyle intervention: a qualitative study in a transdiagnostic sample

Lifestyle interventions are increasingly implemented in mental healthcare. However, qualitative evaluations of such interventions remain scarce, which limits understanding of their suitability, efficacy, and potential effects. This qualitative study explores the experiences of participants with a range of mental illnesses treated in specialist mental healthcare who engaged in the CHAPTER multidomain lifestyle intervention. This transdiagnostic intervention addresses physical activity, nutrition, relaxation, sleep, substance use, social relationships, and purpose and meaning. All ten intervention participants were interviewed at post-intervention and six were interviewed at three-month follow-up regarding their experiences with the intervention, their lifestyle goals, subjective effects and the transition from intervention to daily life. Interviews were analysed using thematic analysis. Participants ( n = 10) positively evaluated the intervention. The multidomain approach was well appreciated, especially the purpose and meaning component. Goals were set across multiple lifestyle domains, beyond nutrition and physical activity. Although group dynamics were considered important, they presented challenges due to heterogeneity in participants’ lifestyle knowledge and levels of functioning. The variety in diagnoses posed no problems. Overall, participants reported positive effects across all recovery domains, particularly in personal recovery, with many reporting notable improvements in self-care and self-compassion. Behavioural changes were sustained or increased at follow-up. Increased awareness, knowledge, and practical tools for behaviour change helped participants achieve their lifestyle goals during and after the intervention. A multidomain lifestyle intervention in transdiagnostic samples with mental illnesses is challenging, but feasible and best meets the real-world clinical practice. Findings suggest that lifestyle interventions may benefit from addressing multiple lifestyle domains, including purpose and meaning, while allowing flexibility to accommodate participant diversity. In addition, future evaluations may benefit from including recovery-oriented outcomes, such as personal growth and well-being, alongside traditional physical and mental health outcomes. This trial was registered at Overview of Medical Research in the Netherlands (OMON) at 04-10-2021 with trial registration number: NL-OMON52338.