AbstractIntroductionPsychiatric patients are considered at risk for malnutrition due to pharmacological treatments, lifestyle habits and the mental illness by itself. Even though metabolic risk factors have been related to worse outcomes in certain conditions, the evidence regarding the nutritional status and its impact on the length of stay in psychiatric inpatients is scarce. This study aims to characterize the nutritional status in acute psychiatric patients, to correlate it with the length of stay, and to find specific potential indicators of malnutrition.MethodsAdult patients admitted to the Hospital Clínic of Barcelona acute psychiatric ward throughout a 1‐year period were included in this cross‐sectional study. Sociodemographic and clinical variables were registered, including length of stay and the nutritional status measured with the CONUT score.ResultsMalnutrition was observed in 42.5% of patients. Plasmatic transferrin saturation, protein and iron levels were inversely correlated with length of stay, having low iron levels an association with longer hospitalizations. The length of stay was not influenced by diagnosis or treatment. Negative correlations with the nutritional status were found in: BMI, cholesterol, triglycerides, albumin, total proteins, prealbumin, iron, lymphocytes and zinc levels, and transferrin saturation. The multivariate analysis showed a significant association for cholesterol and zinc levels, lymphocyte count, and BMI.ConclusionsOur results suggest that nutritional status might influence the course of psychiatric admissions. Cholesterol and zinc levels, lymphocyte count, and BMI might be factors strongly associated with malnutrition. This consideration might allow the identification of profiles in which lifestyle interventions could be implemented.