Averil Hart’s death was an “avoidable tragedy” that would have been prevented had the NHS provided appropriate care and treatment, the Parliamentary and Health Service Ombudsman (PHSO) said.
Its investigation found inadequate coordination and planning of the teenager’s care during a particularly vulnerable time in her life, as she was leaving home to go to university.
Ms Hart, from Sudbury in Suffolk, was voluntarily admitted to the Eating Disorders Unit in Cambridge aged 18 in September 2011.
She had a three-year history of anorexia and was severely underweight with a significant risk to her physical health.
Over the following 11 months as an inpatient she slowly gained weight and doctors decided she could be discharged in August 2012 as she was very keen to take up a place at the University of East Anglia.
Still underweight, she was referred to outpatient eating disorder services in Norfolk for ongoing treatment.
But she was found unconscious on the floor of her student flat by a cleaner just four months later and transferred to hospital, where she died on 15 December 2012.
The report said: “Cambridge Acute Trust’s actions fell far short of what should have happened, and constituted service failure.
“This was the final failure that led immediately to Averil’s death, but it was the last of a long series of missed opportunities to recognise her deteriorating condition and intervene to prevent the need for her final hospital admission as an acutely ill medical emergency.
“The death of Averil Hart was an avoidable tragedy.
“Every NHS organisation involved in her care missed significant opportunities to prevent the tragedy unfolding at every stage of her illness from August 2012 to her death,” it added.
“The subsequent responses to Averil’s family were inadequate and served only to compound their distress.
“The NHS must learn from these events, for the sake of future patients.”
The report calls for junior doctors to be trained about eating disorders as well as greater provision of eating disorder specialists and better coordination of care between NHS organisations treating people with eating disorders.
Dr Bill Kirkup, who led the investigation, said: “Nothing can make up for what happened to Averil and her family.
“But I hope this report will act as a wake-up call to the NHS and health leaders to make urgent improvements to services for eating disorders so that we can avoid similar tragedies in the future.”
A Department of Health spokeswoman said: “We are introducing the first ever eating disorder waiting time standards and investing £150m creating 70 new community eating disorder services across the country, so that no-one will have to go through the same ordeal as Averil.”