Teens weighing 22 stone are being referred to a childhood obesity treatment programme at Temple Street.
There are currently 91 patients waiting for a first appointment for the W82GO healthy lifestyle programme, new figures reveal.
It is the only hospital-based service for clinically obese children aged up to 16 in the country.
The successful programme is delivered by a team including a paediatrician, physiotherapist, dietician, nurse and a clinical psychologist, and it provides families with health, nutrition, self esteem, and activity guidance.
Two patients have been waiting 365 days - nearly a year - since the referral letter was received by the clinic.
However, they have both been issued with appointments. The average waiting time on the list for the programme is 20 weeks.
Senior physiotherapist, Grace O'Malley, who is the programme director said: "Around 22 stone would be the average of our heaviest clients."
In relation to why it takes so long for the issue to be picked up and for the children to be referred on to the clinic, Ms O'Malley explained: "The weight may never actually have been addressed. Sometimes, with the family physician, or someone who is close to the family, they may not want to damage that relationship.
"Other reasons are that if a child goes to see a health professional for another reason, sometimes it can be a negative thing to bring up an unrelated issue, but it is really important to do so."
She said that often there will be a long history of maybe not eating the right foods in the right amounts, of drinking sugary drinks, and not sleeping well. This is necessary for hormonal control and also control of appetite.
"Your sleep controls your growth but also your appetite, so a lot of kids who are not sleeping will gain weight."
She said that poor physical fitness can occur because of the weight as well.
"It becomes harder to move around, and there can be breathlessness, sore joints and there is very often an embarrassment associated with moving.
"A lot of these children are shouted at on the street and bullied by strangers. Some of the stories we have heard have been absolutely horrible."
Cyberbullying can be a problem. A number of patients would report having horrible photos of them posted online.
"We have had some really good success with teens. And when we get the children younger it's easier because they have got growth on their side," Ms O'Malley said.
Meanwhile, Safefood provides families and children with a list of healthy nutrional foods which should be given to children and teens for their school lunches (see panel above).