Fitbits are worrying some high school counsellors who say the fitness device can become a fixation, particularly with girls trying to lose weight and keep fit.
Patrick Walsh, an executive member of the Secondary Principals' Association, told the Weekend Herald some counsellors identified the alleged obsessive nature of the Fitbit as a problem towards the end of last year.
Mr Walsh, also the principal of John Paul College in Rotorua, said he thought the correct approach - as a counsellor had suggested to him - was highlighting it as an issue and taking an educative approach to addressing it.
"[So] the Fitbit is just one part of a total regime [students] might want to use in burning their calories and keeping fit, but not to become totally obsessed or fixated with their Fitbit.
"Some of the Fitbits tell you you have to move and they set you targets and then some [people] become really fixated that they haven't reached theirs. Some counsellors have flagged that as an issue."
The Fitbit is a wrist-worn fitness tracker that, like other pedometers, records the number of steps you take in a day. But it is unique in its ability to wirelessly sync with a computer, smartphone or tablet and keep users updated with their goals and up-to-the-minute progress reports.
Fitbit users can also join groups and compete with friends, and it says how many calories you're burning.
Mr Walsh said girls who were fixated about their weight would then "really worry about keeping moving so they can burn the appropriate number of calories to remain slim".
Another problem would be students constantly looking at the device in class and wanting to get up and move about when they should be focused on their studies. He had not heard of any schools looking to ban Fitbits or similar devices.
Secondary Principals' Association president Sandy Pasley said schools were "really tuned in" when it came to being aware of such issues.
"Schools keep an eye on what's going on and I think that [with] the network within schools, and hearing what's going on, schools are pretty quick to get on to these sort of things pretty smartly and deal with it and involve the families."
Ms Pasley, head of all-girls school Baradene College in Remuera, said she was unaware of schools flagging any new trends or items leading into 2016, but said there was general care around student fitness and health.
"Generally we are, especially at girls' schools, really careful about making sure we get the right messages about healthy eating and healthy exercise and what's too much and warning signs and things like that.
"The Fitbit - that's just symptomatic of people getting obsessed with exercise, isn't it?"
But David Hodge, principal of Rangitoto College on the North Shore, said he was not sure why Fitbits would be an issue. "I would have thought that something that encourages young people to be active was a good thing."
He said he would love to know what evidence the counsellors had for flagging the device.
"I have not read or even heard of any research. With all due respect you can 'fly a kite' over ... the negative impact of [just about] anything and some counsellors are seemingly very good at doing just this."
A Fitbit spokesman said the device was aimed at empowering people to lead healthier, more active lives. The Fitbit terms of service "do not allow users who are under the age of 13 to create Fitbit accounts".