The number of people being diagnosed with eating disorders by specialist teams is rising sharply and some experts link this with social media and cultural messages on girls being thin.
Health Ministry data shows the number of people using eating disorder services last year reached 1354, compared with 897 in 2011 - an increase of 51 per cent.
The ministry said the Government had in 2009 increased funding by $26 million over four years for eating disorder services.
"The steady increase in client volumes since 2009 reflects, in part, success in increased access for clients requiring these services and the increased capacity now being provided by the health sector across New Zealand."
Otago University psychologist Dr Jennifer Jordan told Fairfax that a perfectionist personality, added to childhood trauma, body-image-based bullying, and being bombarded by pop culture images equating thinness with beauty, created a "perfect storm" for teenage girls to develop eating disorders.
Dr Roger Mysliwiec, who runs an eating disorders clinic, said social media could encourage a bad relationship with food, even in those not predisposed to anorexia.
"It still leads people to unhealthy eating behaviour. We are seeing people who become more and more obsessed about what they eat, and then they start losing weight and their health becomes compromised.
"It's quite common that they have engaged with social media, and often to the extent that they have been visiting pro-anorexia sites.
Student Lauren Meale told Fairfax of unwittingly documenting the development of her anorexia on Instagram. Her parents sought treatment for her after her weight fell below 50kg and her BMI was 15 - severely underweight.
Now aged 20, she is using Instagram to record her recovery four years after diagnosis.