Youngsters with urgent eating disorders are waiting too long for treatment, with some waiting months for care.
The mental health trust in Norfolk and Waveney is among one of the worst in England for long waiting times for high-risk patients with eating disorders.
NHS guidelines state patients should get treatment within one week of a referral in urgent cases and within four weeks for routine cases.
But figures from NHS England show only 59pc of under 19s referred to the Norfolk and Suffolk Foundation Trust (NSFT) started their treatment within a week in the 12 months leading up to September this year.
This makes it the 11th worst in the country out of 63 health providers and is worse than the same period last year when 72pc were seen within a week.
The NSFT said patients in urgent cases in Norfolk have been seen within a week since October 2018 and that it is reviewing its Suffolk services.
There has also been an improvement with routine referrals, with September 2019 figures showing 77pc of patients starting treatment within a week compared to 68pc last year.
Rob Mack, from the NSFT's Child Family and Young People's Service, said: "No one is (now) waiting longer than 12 weeks for treatment and we always work with service users to meet their individual needs.
"For example, on occasions, young people and their families are unable to see us within the time frame, postponing appointments themselves through personal choice, family circumstances and life events.
"We remain determined to make further improvements to ensure our young people are receiving timely access to the right specialist care and treatment and are working with our commissioners and partners to achieve this."
Figures show the number of urgent cases more than doubled at the NSFT year on year, from 64 to 132.
As someone who has suffered from anorexia from the age of 12, Mellie Plummer, now 19, from Brundall, said long waiting times can lead to a patient's health deteriorating even faster.
"If you're told you are on a waiting list and waiting for ages, it's like you're not that ill, like what I'm doing is fine.
"It seems like no one is doing anything about it and with eating disorders when you're waiting for weeks the deterioration can be insane.
"By the time you do get treatment you might be worse than when you were referred."
Tom Quinn, director of external affairs at Norwich-based eating disorder charity Beat, said: "Eating disorders are serious mental illnesses but the sooner someone gets help for an eating disorder, the better their chances of a rapid recovery, with lower costs to the NHS.
"The NHS should be doing all it can to ensure everyone who needs treatment can get it, fast."
Earlier this year, further concerns were raised about the service by senior coroner for Norfolk Jacqueline Lake.
She demanded change at the NSFT following the death of Ellie Long, from Wymondham, who suffered from anorexia.
Ellie had been under the care of NSFT when she took her own life in December 2017.
After Ms Long's inquest earlier this year, Ms Lake called on the trust to make improvements on note-taking and communication with other agencies in her report to prevent future deaths.
Mr Mack said the trust took immediate steps following Ellie's death, with all services reviewing their working practices.
"I'd like to say again how sorry we are about Ellie's death and to express our condolences to her family for their terrible loss," he said.
"Our head of patient safety and safeguarding and legal services manager delivered extra training in the regulatory, legal and professional responsibilities each clinician holds when it comes to record-keeping and communication.
"In addition, the trust has transformed its leadership model, creating care groups which are clinically led and put service users and carers at the heart of developing services.
"To ensure that we have done everything we can to make improvements, we have used audits, service user feedback and the outcomes of quality and safety reviews.
"The trust has also introduced a new governance structure to provide the culture and conditions for improvement."
- If you're worried about your own or someone else's eating health, Beat can be reached on 0808 801 0677 or beateatingdisorders.org.uk
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here