BACKGROUND: Rapid weight gain is common with antipsychotic medication. Lost confidence, low mood and medication non-adherence often follow. Yet, the dynamic interactions between the physical and psychological consequences of weight gain, and implications for intervention, are unknown. OBJECTIVES: We examined first-person accounts of weight gain to identify preferences for weight change interventions. DESIGN: A qualitative design was used to explore patients' experiences of weight change in the context of psychosis. METHOD: Semi-structured interviews, analysed using grounded theory, were conducted with 10 patients with psychosis. Sample validation was conducted with peer researchers with lived experience of psychosis. RESULTS: Patients described that initially the extent and speed of weight gain was overshadowed by psychotic experiences and their treatment. This led to a shocking realisation of weight gain. The psychological impact of weight gain, most strikingly on the self-concept, was profound. Loss of self-worth and changed appearance amplified a sense of vulnerability. There were further consequences on mood, activity and psychotic experiences, such as voices commenting on appearance, that were additional obstacles in the challenging process of weight loss. Sedative effects of medication also contributed. Unsuccessful weight loss left little hope and few preferences for interventions. Early information about common weight gain trajectories and working with experts-by-experience were valued. Rebuilding self-confidence, efficacy and worth may be a necessary first step. CONCLUSIONS: The journey of weight gain in patients with psychosis is characterised by loss of self-worth, agency and hope. There are multiple stages in the journey, each with different psychological reactions, that may need different treatment responses.