Disease-related malnutrition can be challenging to treat. A disease, its treatment or the consequences of treatment can cause patients to experience a reduction in appetite and the desire to eat, resulting in an inability to consume sufficient food and drink to maintain or improve nutritional status. This article summarises a four-step approach to identifying and managing patients with disease-related malnutrition, and details how community and primary care nurses can effectively identify and manage the underlying causes of malnutrition and assist in advising on dietary modifications to enable enhanced patient outcomes.