The aim of this study was to explore mental health staffs' experiences of assisting people with psychotic disorders to implement lifestyle changes in an effort to prevent metabolic syndrome. Qualitative interviews were conducted with 12 health care professionals working in psychosis outpatient care in Sweden. Data were analysed using a qualitative content analysis. The results illustrate that implementation of lifestyle changes among people with psychotic disorders was experienced as difficult, but possible. The greatest obstacles experienced in this work were difficulties due to the reduction of cognitive functions associated with the disease. Guidelines available to staff in order to help them identify and prevent physical health problems in the group were not always followed and the content was not always relevant. Staff further described feelings of uncertainty about having to motivate people to take anti-psychotic medication while simultaneously being aware of the risks of metabolic deviations. Nursing interventions focusing on organising daily routines before conducting a more active prevention of metabolic syndrome, including information and practical support, were experienced as necessary. The importance of healthy eating and physical activity needs to be communicated in such a way that it is adjusted to the person's cognitive ability, and should be repeated over time, both verbally and in writing. Such efforts, in combination with empathic and seriously committed community-based social support, were experienced as having the best effect over time. Permanent lifestyle changes were experienced as having to be carried out on the patient's terms and in his or her home environment.