Cancer anorexia-cachexia syndrome (CACS) is a devastating and debilitating aspect at any stage of malignancy. It presents primarily as anorexia, weight loss and muscle wasting secondary to inadequate oral intake and metabolic changes. This syndrome is highly prevalent among cancer patients, has a large impact on morbidity and mortality, and impinges on patient quality of life. The pathogenic mechanisms of CACS are multifactorial. It is suggested to be the result of tumor-host interactions and cytokines have a siginificant role. Diagnosis of cancer cachexia is complex and multifaceted and requires meticulous clinical examination of the patient. The challenge for clinicians is to know how best to manage the symptoms of weight loss and anorexia for optimal patient outcome. This article outlines the diagnosis of cancer cachexia, reviews its impact on patient quality of life and survival, and updates the reader on potential therapies that may suppress it.