There is a lack of agreement over the usefulness and coherence of the term 'severe and enduring' to denote a sub-category of illness amongst patients with eating disorders. Nonetheless, a proportion of patients experience longstanding and severe illnesses, often as a result of a lack of treatment altogether, or poor responses to currently available treatments as they are delivered within existing specialist services. This paper is written from the perspective of lived experience and published research. It calls for a re-imagination of existing principles within the field of eating disorders which have underpinned recent demonstrable improvements in clinical practice and outcomes for patients, namely prevention and early intervention. These concepts can also be applied in the development of more effective and inclusive care pathways for patients with longstanding and severe eating disorders. The author reminds us of the importance of language in the description and categorisation of illness, and the essential requirement that those with lived/living experience of illness share equitable decision-making power in defining their condition and designing the healthcare provision they receive.