Oesophageal cancer is a debilitating disease with a poor prognosis, and weight loss owing to malnutrition prevails in the majority of patients. Cachexia, a multifactorial syndrome characterized by the loss of fat and skeletal muscle mass and systemic inflammation arising from complex host-tumour interactions is a major contributor to malnutrition, which is a determinant of tolerance to treatment and survival. In patients with oesophageal cancer, cachexia is further compounded by eating difficulties owing to the stage and location of the tumour, and the effects of neoadjuvant therapy. Treatment with curative intent involves exceptionally extensive and invasive surgery, and the subsequent anatomical changes often lead to eating difficulties and severe postoperative malnutrition. Thus, screening for cachexia by means of percentage weight loss and BMI during the cancer trajectory and survivorship periods is imperative. Additionally, markers of inflammation (such as C-reactive protein), dysphagia and appetite loss should be assessed at diagnosis. Routine assessments of body composition are also necessary in patients with oesophageal cancer to enable assessment of skeletal muscle loss, which might be masked by sarcopenic obesity in these patients. A need exists for clinical trials examining the effectiveness of therapeutic and physical-activity-based interventions in mitigating muscle loss and counteracting cachexia in these patients.