The government is standing by its stance to not introduce a sugar tax despite an open letter by 74 health professors urging it to do so.
The letter also accused ministers of being frightened off from implementing policies and spooked into inaction by drinks companies.
The professors, who are from universities around the country, said New Zealand had an appallingly high rate of childhood obesity, the fourth highest in the world and every year more than 5000 children under eight-years-old needed an operation to remove rotten teeth.
Green Party health spokesperson Kevin Hague said the government had it wrong when it came to fighting childhood obesity and it needed to start listening to the experts.
"To get 70 of the foremost public health academics in the country to sign a letter like this shows they are absolutely exasperated," he said.
"These public health experts who have come out are the best qualified in the country to interpret the evidence that is available, and they're saying there is enough evidence, just get on and do it."
The professors also accused sugary drinks companies and the Food and Grocery Council of behaving like the tobacco industry by "creating doubt in the public's mind and spooking politicians into inaction."
Mr Hague said the government needed to start treating diabetes like smoking-related cancers.
"When we look at the effort that has been put up against tobacco related disease, we see restrictions on where the product can be sold, [and] we see the aggressive use of taxation. What we see on obesity-related disease is a government that's not prepared to do any of those things."
Health Minister Jonathan Coleman has said multiple times New Zealand would not consider bringing in a sugar tax because there was no conclusive evidence it would decrease obesity.
In the letter, the professors hit back saying the evidence supporting a sugar tax is "stronger than the evidence for any of the 22 strategies in the government's existing plan."
But Mr Coleman said the government was sticking with its position.
"The bottom line is, and I'm surprised these guys are so focused on this, there is no evidence," he said.
"There's actually a heck of a lot else that can be done and we've got a comprehensive package there with 22 different initiatives, a lot of it is focused on changing behaviour through the health system and education system."
Mr Coleman said the government was keeping an eye on two international sugar tax studies that will come out in the next year.
Labour's health spokesperson Annette King said her party had not ruled out bringing in a sugar tax if it was elected to government - but it too was waiting for more evidence.
"We've said we want to see the evidence that is coming out of Mexico, a country that has put a tax on sugary drinks, and we'll base a decision on good evidence - and evidence is starting to emerge," she said.
But Maori Party co-leader Marama Fox said the longer it took for a tax to be introduced, the more damage would be done.
"It's always the children that suffer. We need to ensure that our children don't need to grow up and make healthy choices, [but] that healthy choices are a way of life," she said.
The United Kingdom announced it was bringing in a sugary drinks tax last month and 18 countries now have the tax in place.