Objective: To explore changes in eating behaviours, inherent weight gain and the metabolic consequences in severely mentally ill patients treated with antipsychotic medications. Method: We conducted a comprehensive review of studies that investigated eating behaviours in mentally ill patients taking antipsychotic treatments. We included records that considered weight change and/or varying degrees of adverse metabolic effects and related metabolic disturbances, such as obesity, dyslipidaemia, type 2 diabetes mellitus, hypertension, metabolic syndrome and cardiovascular diseases. We adopted a systematic approache (PRISMA) and considered 4 electronic databases: PubMed, Medline, Embase, and Psychinfo. Moreover, we conducted a manual synthesis of the bibliographies of the identified articles. Results: We identified 29 full-text human studies that investigated the relationship between antipsychotic drugs and changes in eating behaviours resulting in weight gain and other metabolic complications. Twenty-one of the 29 studies demonstrated the emergence of at least one mechanism of disturbed eating behaviour underlying the weight-promoting effects of antipsychotic medication, whereas six studies reported no impact. Conclusion: Despite the limitations of this review, we can conclude that second-generation antipsychotic (SGA) treatment plays a significant role in the weight gain of patients affected by serious mental disorders because these drugs can lead to abnormal appetite, excessive food intake, and cognitive disinhibition, resulting in high morbidity and mortality. The interest in evaluating eating and feeding behaviours in severely mentally ill patients taking psychotropic drugs is still nascent, and studies in the field are scarce and heterogeneous. Future studies should include long-term, double-blind randomized controlled trials with a large sample size and comparable data for several antipsychotics as well as standardized and validated tools to measure eating behaviours.