New research has found that the causes of anorexia are likely to be metabolic as well as psychological.
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The study, published in Nature Genetics, suggests that people are born with a biological predisposition to developing the disorder, that affects the function of the brain as well as the metabolic system.
It reports that there are very specific variants within an individual person's DNA that makes them more likely to develop anorexia.
Among the 17,000 previously anorexic individuals that contributed their DNA to the global study, 500 were from New Zealand.
Christchurch's University of Otago professor of genetics Martin Kennedy, who worked on the study, said the study helped in understanding the underlying biology of anorexia.
"We've managed to find a number of sites in the human genome that seem to be associated with a predisposition for the illness," Prof Kennedy said.
"It gives us some handles on the underlying biology, something we don't understand at all, which is the case of many mental disorders."
Samantha Plunkett - diagnosed with anorexia when she was 11 - was one of the individuals to contribute to the study.
"It was very confusing for myself, because I didn't understand it, so I didn't know really know how other people could understand it," she said.
"And it was a really lonely time. You feel really isolated when you're away in hospital, or recovering at home.
"I think a lot of pressures at school definitely brought it on. I didn't quite feel like I fit in, in my year group.
"I also felt like there were a lot of other aspects that were out of control so I used food to control those situations."
The eating disorder, anorexia, has the highest mortality rate of any other psychiatric disorders, and it predominately affects young women.
Doctor Jenny Jordan, clinical physician and senior lecturer at University of Otago in Christchurch, said the study was a significant step that could have an impact on future treatment.
"If we can think about those things - they're not just related to the acute state of anorexia, these things have been there since conception, this is a risk factor that people are born with.
"So it might help us to understand why people develop this condition, and predict at-risk people, and perhaps the biological pathways will point to treatments down the track.
"So we might get better outcomes if we focus on the metabolic as well as the psychiatric."
Although the researchers are clear that this is just the start with even larger studies in the pipeline, for one parent it's a very important moment.
Nicki Wilson is the chair of the Eating Disorder Association of New Zealand, which was heavily involved with the study. Nicki's daughter developed anorexia when she was 16.
"I feel really really hopeful," she said. "It just enables you to completely put aside any guilt or blame of any individual or their family which prevent barriers to seeking and engaging effective treatment. And just to get on with seeking that treatment."
When scientists started appealing for individuals who had developed anorexia to contribute DNA to their study in 2016, Dr Jordan said they were overwhelmed by the response.
Samantha contributed her DNA in hope for answers.
"It was actually quite emotional reading the results and hearing about what they've discovered," she said.
"It definitely kind of clicked a few things for me, like 'yeah, that actually makes sense', as to why things were hard for me in that way.
"It was quite emotional reading those results and finding out that it's not just all in your head and that there is something that's contributing to why you're suffering from anorexia."
If you or a loved one is showing signs of anorexia, or if you're worried about the way you or a family member is eating, it is important to seek help straight away.
You can find more information on what to look out for here.
The best way is to go to your GP and ask for a referral to an Eating Disorder specialist service.
If you would like advice on what to do, you can call the Eating Disorder Association of NZ, on 0800 2 EDANZ.