Just half the people with eating disorders who contacted a helpline last year were in treatment, a new report has revealed.
The largest age group of callers were between 25-35 years and many had the eating disorder for 10 years or more.
Bodywhys, the support group which runs the helpline, said the high proportion of older people highlights how eating disorders are not just a teenage issue.
A minority of the callers were over 56 years and one in 10 were between 10 and 14 years, the organisation's annual report revealed.
Around 26pc had bulimia and 25pc anorexia. Another 26pc had a binge-eating disorder. Others had unspecified eating disorders.
"Callers do not always disclose whether they are in any form of treatment. Where this is mentioned, it is worth noting that where known, 50.3pc were currently in some form of treatment."
More than one third were getting psychotherapy or counselling and a similar proportion were seeing their GP only. One in five were getting psychiatric or hospital treatment. Although most were female, as many as 8.5pc were male.
The users of a separate online support group for teens were mostly aged 16-18 years. The vast majority were female.
It also conducted 108 face-to-face support groups and 74pc of these were over the age of 25. One in five of these were men. While 48pc of the callers to its helpline suffered eating disorders the rest were family members and friends.
The organisation said it recognised that an eating disorder is not primarily about food or weight but rather is a coping mechanism that a person uses to help them manage and live their lives.
"In this way Bodywhys support services strive to listen first and foremost and in so doing helps the service user to think about the situation they are in and consider the options they have open to them to move towards recovery."
Harriet Parsons, services co-ordinator with Bodywhys, said: "The figures from our annual report for 2013 clearly reinforce what Bodywhys has been saying for some time, that eating disorders are not unique to teenagers.
"Many people have been dealing with an eating disorder for a significant period of time. Sending an email or picking up the phone is something they may be terrified of doing at first.
"However, the feedback from across all of our support services indicates that people value being listened to, they have very real support needs and in many cases feel isolated.
"As well as the figures from last year, we have also seen significant increase in uptake of our services in the first six months of 2014."
Between January and June there has been a 92pc increase in helpline callers, and a 250pc rise in attendance at YouthConnect, the online group for teenagers has also been recorded.
Bodywhys Helpline LoCall 1890 200 444.Bodywhys Online Support Groups are available at www.bodywhys.ie.
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