ABOUT one-in-five Hunter adolescents have experienced a "significantly impairing" eating disorder, and new data shows they are developing them earlier than previously thought.
The latest results from a longitudinal study of more than 5000 students has found that 22.2 per cent - just over one in five - participants aged 12-to-19 had experienced a "clinical or subclinical" eating disorder during their adolescence.
The results, published in peer-reviewed journal Psychological Medicine, showed that while eating disorders were more prevalent among girls, they were also a significant problem for boys.
"About one-in-three girls met criteria for one of these eating disorders, but when it came to boys, there was about 13 per cent that met the criteria too," study lead, Dr Deborah Mitchison - a NHMRC Research Fellow at Western Sydney University - said. "But in this study, we haven't presented the findings for muscle dysmorphia - which is expected to be much higher in the boys. We are hoping to publish those a little bit later."
Of the 13 schools that participated in the EveryBODY study, 12 were from the Hunter Region.
Dr Mitchison said they had a strict criteria threshold to ensure they did not "over-diagnose".
"In the 'DSM-5' - the diagnostic manual for psychologists and psychiatrists - eating disorders are one of the few disorders where they don't specify that there must be distress and impairment attached to it," Dr Mitchison said.
"Whereas to diagnose an anxiety disorder or depression - or pretty much any other mental health disorder - the symptoms must be associated with distress and impairment.
"For this study, even when we took the most stringent and strict definition of stress and impairment, the prevalence of eating disorders was still 14 per cent, which is huge. I was not expecting these rates to be so high.
"But more than one-in-five kids still meeting criteria for a significantly impairing eating disorder is shocking."
Dr Mitchison said they had also found the "age of onset" of eating disorders appeared to be lowering.
"We used to see that anorexia nervosa probably had a peak age of around 15, and bulimia nervosa around 18, for the onset of these disorders," she said.
"But in the study we found no difference in the likelihood of say a 13 year old meeting criteria for anorexia nervosa, and an 18 year old."
Dr Mitchison said the study had highlighted the prevalence of eating disorders, and the need to tackle them early, and systemically.
"We know that if we can catch it early, there are really good outcomes and we can reduce the time that is spent in the eating disorder, the impact on the family, and the individual," she said.
"If you don't treat them, they can have a really long course, and because they are a disorder that really targets young people at such an important part of their life - it can affect their school grades, which can go on to affect what kind of employment they are going to get, their relationships, their physical and social health."
Dr Mitchison said they found bulimia nervosa, and its variants, to be the most prevalent disorder among study participants.
"Bulimia is categorised by frequent binge eating - overeating with this sense of a loss of control, and then trying to compensate for any weight gain that might happen by dieting or fasting, vomiting or taking laxatives or diuretics," she said.
"About 4.6 per cent of the kids in this study met criteria for bulimia nervosa, and a further 2.1 per cent met criteria for sub-threshold bulimia nervosa - so, similar symptoms, but happening at a less frequent rate.
"Purging disorders are also quite similar - the same as bulimia, but without the binge eating. So vomiting, or taking laxatives, after eating a normal amount of food. About 3.2 per cent met criteria for that."
Dr Mitchison said they had partnered with The Butterfly Foundation to implement and test body image programs at Hunter schools, which would include the new RESET program for boys.
In August, teachers at participating schools would undergo a four hour training session in programs that targeted muscularity, body dissatisfaction, and body image issues in boys, as well as girls.
"The schools will then roll it out and we will evaluate it to see if it's actually targeting some of those body image concerns, and whether it is actually reducing them," she said.
Her research team was also looking into social media's role in body image.
"Previously a lot of research prior to social media talked about magazines," she said. "But with magazines, it was such a limited amount of time you would spend opening and reading it. Whereas social media is pervasive - people are checking their Facebook or Instagram or Snapchat all the time."
She said teenagers were no longer just comparing themselves to celebrities, but "digitally manipulated" versions of their friends and peers.
"Which in some ways is more dangerous because you expect, in some way, that you should be able to look as good as your peers," Dr Mitchison said.
"So there is this expectation that you should look thin and 'perfect' all the time. Everyone is posting idealised versions of themselves and their body online, all the time, and monitoring the likes and the comments - and it just feeds into this investment into trying to maintain idealised bodies."
Dr Mitchison said both boys and girls were shown to be similarly affected by "night eating syndrome".
"This was experienced by almost 5 per cent of boys, and about 3.6 per cent of girls," she said.
"At the moment it is categorised as an unspecified eating disorder, and it is defined as eating the majority of your daily food intake after the evening meal, or waking up in the middle of the night to eat.
"It seems to be attached to a belief that in order to get back to sleep, I need to eat.
"It needed to be associated with distress and impairment as well."
If you have recognised one or more of the above symptoms in yourself or someone you care about, contact the Butterfly Foundation Support Line on 1800 ED HOPE.
Dr Mitchison said there was a misconception that people with an eating disorder were always "very thin", as most people still tended to associate the idea with anorexia nervosa alone.
"For most eating disorders there is actually an increased risk of gaining weight rather than losing weight, and I think that is part of the impairment that can be overlooked," she said.
"People with bulimia nervosa were 2.3 times more likely to be obese than adolescents who didn't have an eating disorder.
"It is a problem because that stereotype of it being something that affects really thin children feeds its way into general practice and among many teachers and doctors who are otherwise a really important part of identifying eating disorders early.
"If you have this idea that people with eating disorders must be thin, then you may not pick up an eating disorder in a child who is on the larger end of the weight spectrum."