Most of the patients are said to be teenagers and young adults who have been transferred hundreds of miles from home into residential care units in Glasgow and Edinburgh.
Campaigners have voiced grave concerns that the practice is adding pressure to vulnerable patients already in a “life-threatening situation”.
Health Secretary Jeremy Hunt said it was “unacceptable” and work was under way to eradicate “inappropriate out of area placements” over the next five years.
The Guardian spoke to the family of one 17-year-old who spent time in units in Watford, Hertfordshire, London and Colchester, Essex, before being moved to Edinburgh for life-saving treatment.
Anup Vyas, from Hemel Hempstead, said his stepdaughter was treated near their home in Hertfordshire for a rare eating disorder before she was moved from unit to unit across the South East.
He told the newspaper her condition is so severe that she is “basically being kept alive in Scotland. NHS England acknowledge that her being so far away is not ideal.”
Jane Smith, chief executive of Anorexia and Bulimia Care, told the newspaper: “I’ve seen a rise in calls from people saying their children have been sent far away, miles away, to be looked after because there are either no services nearby or they are full.
“This is a life-threatening situation for young people. People are in in-patient care because they are at risk of dying. They are in a very fragile, risky state.”
NHS England said £1.4 billion of cumulative funding will be invested in young people’s mental health services over the next five years.
“The NHS recently laid out very clear plans to expand staff and services for specialist eating disorders and other mental health problems, in order to tackle and eliminate distant out of area placements,” a spokeswoman told the newspaper.
Ministers have also earmarked £150 million for enhanced services in the community.
The Health Secretary said: “It is clearly unacceptable for people to be sent hundreds of miles away for care at a time when they need the support of friends and family the most.
“That’s why in April we committed to a national ambition to eliminate inappropriate out of area placements by 2020-21.”