Healthcare professional perspectives on antipsychotic-induced weight gain: realist evaluation from the RESOLVE study.

BACKGROUND: Weight gain is a common, distressing side-effect of antipsychotic medication prescribed for people with severe mental illness. National guidance for antipsychotic-induced weight gain (AIWG) encourages early intervention and physical health monitoring; healthcare professionals (HCPs) often struggle to implement these recommendations in routine care. AIMS: To explore how HCPs understand and respond to AIWG for patients. METHOD: This realist evaluation, part of the RESOLVE project, builds on a realist synthesis. Thirty HCPs participated in realist interviews. A programme theory with nine context-mechanism-outcome configurations (CMOCs) was generated, explaining how HCPs perceive non-pharmacological care provision for patients with AIWG. Clinical and lived experience stakeholders reviewed and refined the theory and CMOCs. RESULTS: The nine CMOCs spanned three areas: (a) systemic and professional challenges; (b) strategies to enhance individualised and meaningful support; and (c) the role and limitations of non-professional support. HCPs described how lack of training, siloed services and system-level constraints limited their ability to offer integrated care. They highlighted the importance of relational continuity, early and tailored conversations, and alignment with patients' values and motivations. Peer and family support were valued, but structural barriers undermined their consistent implementation. CONCLUSIONS: AIWG was experienced as compromising professional values for HCPs working in mental health settings. Person-centred care was often undermined by fragmented systems, role ambiguity and insufficient training. These issues require investment in professional development, structural integration, and relationship-based approaches that support timely, collaborative action.