BACKGROUND: An unhealthy lifestyle plays an important role in the substantially reduced life-expectancy of inpatients with severe mental illness (SMI). However, there is a lack of evidence on the long-term effectiveness and implementation of lifestyle improvements in inpatient mental healthcare.<br/> AIM: Increasing knowledge and understanding of (the implementation of) lifestyle changes in inpatients with SMI in longer-term clinical care.<br/> METHOD: Cross-sectional research followed by an observational study to evaluate a multidisciplinary lifestyle enhancing treatment (MULTI) for both changes in health-related outcomes after 18 months compared to treatment as usual (TAU), and the implementation barriers and facilitators.<br/> RESULTS: Patients were very sedentary and less physically active compared to people without SMI. After 18 months, MULTI showed significant improvements in total physical activity, cardiometabolic risk factors, psychosocial functioning and mediation use, compared to TAU. Physical health did not improve in TAU. The implementation of MULTI was hampered by organisational factors and facilitated by positive attitudes of healthcare professionals and patients towards MULTI and their own role in it.<br/> CONCLUSION: Using a multidisciplinary integrated approach, it is possible to improve the lifestyle, and thus the health status, of SMI inpatients, within the current context of routine mental healthcare.</p
