Protocol of an Efficacy Study on Nursing Consultation in Weight Management and Metabolic Syndrome Based on the Carbohydrate–Insulin Theory in Individuals with First-Episode Psychosis

<b>Background</b>: Individuals with severe mental illness live, on average, up to 30 years less than the general population, with cardiovascular disease being the leading cause of death. Metabolic syndrome (MetS) plays a significant role in this, making it crucial to manage this issue in individuals with psychosis at the onset of the illness. The approach to managing this issue has evolved from a focus on calorie counting to a deeper understanding of hormone function, particularly the role of insulin resistance in MetS. Therefore, incorporating this perspective into mental health nursing consultations with individuals experiencing psychosis is of great interest. <b>Methods</b>: In accordance with the SPIRIT guidelines, an open randomized clinical trial is proposed, involving patients from a first-episode psychosis program. <b>Results</b>: The primary outcome will be significant weight loss (≥5%). Secondary outcomes will include changes in metabolic parameters, psychopathological status, quality of life, and physical activity. Participants will be assigned to two groups: one group will attend a series of six previously manualized nursing consultations, while the other will continue with their usual treatment. Results will be evaluated at six months and one year. <b>Conclusions</b>: This study will determine whether a mental health nursing consultation based on the carbohydrate-insulin model of obesity is effective in reducing weight and the risk of MetS in individuals with early-onset psychosis. This study was retrospectively registered on Clinical Trials-NCT06650943.