Anorexia nervosa affects 0.5% of the population (90% female) with the highest mortality of any psychiatric illness, usually suicide, or cardiovascular or neurological sequelae of either malnutrition or refeeding syndrome. The latter two conditions occur in the inpatient setting, carry a high mortality and are thoroughly avoidable with careful informed clinical management. This paper provides an overview of the service and care of these patients in a general hospital setting in Ireland. In response to a number of acute presentations a cross discipline Pop-up Eating Disorder Unit (psychiatrist, physician, dietician, nurse) was established in Sligo University Hospital in 2014 and has experience of 20 people treated according to the MARSIPAN guideline (Management of Really Sick Inpatients with Anorexia Nervosa). They are nursed in a designated ward with continuous cardiac monitoring (in addition 2 required ICU admission), with one-to-one continuous supervision, complete bed rest, careful calorie titration (usually nasogastric) with twice daily phosphate, magnesium, calcium and potassium concentrations measured and replaced. Sabotaging behaviour witnessed includes micro-exercising, requests for windows to be opened (in order to shiver/micro exercise), food concealment, faecal/urinary loading on weighing days, heavy hair accessories, vigorous page turning/toothbrushing/use of computer keypads and animated conversations. A cross disciplinary coordinated approach to this cohort, who often inventive in their resistance to treatment, allows safe management in a general hospital setting.