An increasing number of young women are starving themselves for days before drinking to keep their calorie intake levels down, says an expert.
The alarming trend, dubbed "drunkorexia", is on the rise with Kiwi women aged 18-30, said Eating Difficulties Education Network (EDEN) counsellor Victoria Marsden.
"Drunkorexia is characterised by mostly restricting the day before, the day of, and the day after going out drinking. Restricting meaning skipping meals, not eating at all or eating very little in order to counterbalance or contradict the calories that alcohol contains."
Ms Marsden said women were also vomiting their meals as part of the behaviour to try and maintain a slim body weight.
"I think a lot of it is being influenced by the culture that we live in in terms of being very focused on ideal body image and bodies in general, with young women having to fit the ideal."
She said food restrictions could be doing long term damage to their bodies, based on the person's situation and intake.
"There are some really concerning aspects of it, particularly if someone has been restricting or starving themselves and then drinks a significant amount of alcohol, they can find themselves drunk very quickly and then in unsafe situations."
Ms Marsden couldn't name the number of cases she saw per month, but said the problem was "definitely growing".
Drunkorexia often went unnoticed and unreported as it was seen as normal for many young women, she said.
"We live in a culture where binge drinking is such a significant part of young people's lives, often it's under-reported or not reported at all. Lots of young women just see it as part of going out, and it spills over into the next day with restricting [food]."
The behaviour can be treated by educating women about the dangers of binge drinking and restricting food and by addressing body ideal pressures.
Research into the subject could help find the cause of the behaviour, she said.
"When does it cross the line from general preparing for going out in the evening with a day of drinking. I suspect it's a lot more common that there be a whole spectrum of what we're calling drunkorexia, so from the real restricting the day before, the day of and the day after, to perhaps not having dinner."
Academic studies into the behaviour have been mainly conducted overseas.
A University of Missouri study into the issue found 16 per cent of those surveyed restricted calories to save them for drinking.
Co-author Victoria Osborne found people who participated in drunkorexia were more at risk for violence, risky sexual behaviour, alcohol poisoning, substance abuse and chronic diseases later in life.
Alcohol Healthwatch health promotion advisor Chris Rogan said more research was needed on women foregoing food to drink alcohol.
"What we think is that we just have very little research on any of the less-obvious or less overt harm that comes from alcohol. It's an addictive substance, it's a mind altering substance.... We think there's a huge iceberg of problems out there, and [drunkorexia] is one of them."
She said large amounts of alcohol depletes micronutrients and nutrition, which will be harming the normal day-to-day function of their bodies.