Hannah Yelland, 16, is one of the first in-patients at the Becton Centre for Children and Young People, which has been developed by specialist psychiatric professionals from the Sheffield Children's Hospital NHS Foundation Trust.
The centre, which has been built to provide support for children aged between five and 18, replaces a number of separate units, and is designed to help children and parents who cannot deal with mental illness in a family setting.
Professionals at the centre, which provides secure accommodation for youngsters with 24 bedrooms, an in-hospital school and a padded "safe room" are able to deal with a range of conditions including anorexia and ADHD.
Hannah, who comes from Thurcroft, near Rotherham, was diagnosed with her eating disorder more than a year ago after collapsing at school. She was initially admitted to Sheffield Children's Hospital but was then transferred.
Before the new centre opened she had been a resident at Sheffield's Oakwood facility, which has now been replaced by the Becton Centre. She said the new facilities had helped her find new resolve in her fight against her illness.
When she was admitted her body mass index was too low for her age, gender and height and doctors have decided that she needs to be tube fed while nurses work to introduce foods like cereal bars and toast back into her diet.
The teenager has been assigned her own "mini team" of professionals, by the trust's Child and Adolescent Mental Health Service (CAMHS), who are working with her parents to help them deal with the potentially fatal condition.
Hannah said: "It came on quite quickly. After I ate I felt really fat so I would exercise afterwards. It was affecting my school work because I was fainting all the time. But I didn't want to talk about it to anyone or get any help.
"But the mini team here have been brilliant and they are helping to sort out my diet. It was very difficult to begin with. I cried all the time. I got used to it after a couple of weeks and now I've got friends here."
She said she had introduced biscuit into her diet, but found it really difficult. "Now I want to do it and I try not to think about exercise or getting too fat."
The average stay for a child at the Becton Centre will be around four months, although Hannah has been an in-patient for more than a year. Dr Nevyne Chalboub, the clinical director of CAMHS, said some child cases could be very complicated.
She said: "Parents are often very frightened and concerned about their children being admitted to hospital for a mental illness, but this new centre means that children in the region have the best facilities in the country here.
"Bringing the services under one roof offers a modern, flexible and individual service to young people and they benefit from having all the health professionals involved in their care based on the one site."
Hannah's mother Carol McAuley, 45, who has three other daughters aged between 21 and seven and a son aged nine, described her family's experience as "horrendous and terrible" but said staff had helped make things better.
She added: "It has got a bit easier now because Hannah has accepted her feeds but in the beginning it was awful. The care has been very good and they are getting Hannah better.
"I've done a lot of research and read a lot of books, but I just wish I had know how to deal with it sooner as a mother. We do a lot of talking and we get a lot of support from her sisters, they find it very difficult to understand why someone doesn't want to eat."
The Becton Centre has been funded by primary care trusts in Sheffield, Doncaster, Rotherham, Barnsley and north Derbyshire and will treat youngsters from across the area. It fully opened to all patients last month.
Aid for region's troubled young
Staff at the 12m centre will deal with 150 people a year aged five to 18
Conditions which will be treated include attention deficit hyperactivity disorder ADHD and Obsessive Compulsive Disorder (OCD)
The centre includes therapy rooms, a school and 24 bedrooms, including a padded "safe room"
An average stay for a child inpatient in the secure hospital area is around four months
The centre provides support for children and their parents who find it hard to deal with mental illness in a family setting.
Services for children with learning disabilities will also be provided.
It fully opened to all patients in November.