A 16-year-old girl collapsed in cardiac arrest in a hospital car park. Investigations revealed a potassium level of 1.8. Following a 5-day intensive care unit admission she described behaviours consistent with restrictive-purging type anorexia nervosa, which had been concealed from her parents and health professionals. Long-term management has been difficult due to poor patient engagement. Further, recurrent episodes of hypokalaemia continue to feature. Here we explore the cardiac complications of anorexia nervosa and challenges with long-term management of this condition.