A leading New Zealand obesity campaigner is quitting the battle, saying she has achieved nothing in 14 years.

Photo: 123RF

Robyn Toomath started Fight the Obesity Epidemic in 2001 when, as a diabetes specialist, she started seeing teenagers with type-two diabetes; it had previously affected only people aged over 40.

She has consistently called for tougher rules on the advertising and marketing of junk food to children, and also advocates a tax on sugary drinks and a junk food ban in schools.

Dr Toomath said she was sick of fighting for change and getting nowhere, with the obesity rate growing to at least one in three adults and one in three children.

"Clearly I've made no progress. There's not a single thing that comes to mind other than the district health boards are going to provide a healthy food environment for their staff," she said.

"I mean really, it's pathetic that that's all we can think of."

Photo: Supplied

She said she saw the effects of obesity every day in her job as Auckland Hospital's clinical director of general medicine.

"Every single ward round, I am seeing patients that are morbidly obese, and have medical problems as a result. We are ordering more and more large sized beds, we're ordering more hoists. It's expensive, and there is going to be more of it."

She said healthy living programmes were aspirational but they were also stigmatising and would not make a difference to the obesity crisis.

"Most people will lose weight for six months, maybe 12 months .But if you look five years out, about 85 percent people are right back where they were and many of them are much fatter. So all the evidence shows that trying to lose weight by all the methods that are available, short of bariatric surgery is unsuccessful."

Dr Toomath said she was still optimistic that a future New Zealand government will take a harder line with the food industry.

The latest move in the government's plan to tackle childhood obesity is an ad campaign using sports stars to encourage people to think about what they eat.

Health Minister Jonathan Coleman said programmes involving personal responsibility, education around healthy eating and exercise were the answer, not regulating the food industry.

"If you go out there and talk to a range of people in the street, I think you'll find they will say this sounds about right - personal responsibility is actually a part of it. We're strengthening up PE and exercise in schools, we're putting a big focus on education and changing family cultures. But no, we're not going to regulate."

Dr Coleman said the government will continue to work with the food industry, which has already made gains in reducing fat, salt and sugar.

The Labour Party said today Dr Toomath was underestimating the impact she had made with her fight.

Labour's health spokeswoman Annette King said people's attitudes towards obesity and food had changed thanks to Dr Toomath.

"She has often been the lone voice that was standing up and talking about obesity in New Zealand, the impact it was having, the need to address it, the need to have policy. And she has had to face a lot of critics, but I think she has underestimated the impact she has made."

Meanwhile, the Green Party said Dr Toomath's decision showed governments had favoured the junk-food industry over people's health.

Greens co-leader Metiria Turei said successive governments have ignored the advice of doctors and specialists on the crisis.

"Dr Toomath is a world-recognised specialist in this area, and for her to feel quitting was the only option shows how the government really has no interest in promoting and supporting the health of New Zealanders."

Dr Toomath said her book on obesity, to be released next year, would be her swansong.

RNZ's Insight will explore the obesity crisis on Sunday morning.