OBJECTIVES: When compared to the general population, people with severe mental disorder (SMD) more commonly show obesity, sedentary lifestyles and poor dietary choices. This review examines the effectiveness and cost-effectiveness of lifestyle interventions on physical activity and dietary choices in people with SMD. Included health outcomes were changes in weight, body mass index (BMI) and quality of life. METHODS: A systematic E-search strategy was conducted using Medline, Web of Science and CINAHL to select articles of lifestyle interventions targeting exercise and dietary choices in people with SMD. In addition, the reference lists of retrieved articles from the E-databases were hand-searched. RESULTS: The search strategy produced 14 randomized and non-randomized comparative trials that met the inclusion criteria. Mean duration of the interventions was 20.0±10.84 weeks. Weight loss was reported in 11 studies, with a mean weight change of -1.96±1.84 kg in the intervention groups versus +1.77±2.12 kg in the control groups. Changes in BMI were -0.87±0.69 kg/m² and +0.64±0.96 kg/m² respectively in intervention and control groups. Differences in changes in weight and BMI between intervention and control groups were statistically significant in nine studies. The results also suggest that quality of life and general health could benefit from these kinds of interventions. For example, subjective improvements in quality of life (p=0.047) and in overall health (p=0.023) were found in the study of Evans et al. (2005). In none of the studies, however, cost-effectiveness was examined. CONCLUSIONS: Small weight loss through lifestyle interventions targeting physical activity and dietary choices is possible in people with SMD. This is promising given the high prevalence of sedentary lifestyles and poor dietary choices and the effects of some atypical antipsychotics on weight gain. Further study of both effectiveness and cost-effectiveness (including the most cost-effective ‘dose’) of lifestyle interventions in people with SMD is required.