Anorexia nervosa (AN) is a life-threatening mental disorder that is associated with substantial caregiver burden. Carers of individuals with AN report high levels of distress and self-blame, and insufficient knowledge to help their loved ones. However, carers can have a very important role to play in aiding recovery from AN, and are often highly motivated to assist in the treatment process. This manuscript presents the protocol for a randomised controlled trial (RCT) of We Can, a web-based intervention for carers for people with AN. The study aims to investigate the effectiveness of We Can delivered with different intensities of support.