Economic insecurity is likely to be a major factor in New Zealand's growing obesity epidemic, University of Otago economist Dr Trenton Smith believes.

Dr Smith, a senior lecturer in economics, was speaking in Dunedin yesterday at the Otago International Health Research Network's fifth annual conference.

Speaking later, he said obesity also often led to adverse health and social outcomes.

Some countries, including New Zealand, had pursued market liberalisation policies, in which some state assets had been privatised and more market approaches adopted.


Some economic risks linked to employment had effectively been transferred from the state to individual workers and their families, contributing to increased insecurity among some employees.

Research showed strong links between such countries - including New Zealand - and rapidly rising obesity problems.

"There's a lot of evidence," he said.

In the United States in 2007, 33 per cent of the population was classified as obese, followed by New Zealand (27 per cent) and the UK and Ireland (24 per cent). Australia, Canada and Spain all had obesity rates of more than 15 per cent.

In the UK, a government study of many thousands of civil servants found that body weight had increased significantly among workers in one government department which had been switched to private sector control, increasing their insecurity about retaining their jobs, he said.

Many economic studies aiming to trace the cause of rising obesity rates around the world had focused on food markets, high-calorie foods having become cheaper and more widespread.

He noted that, in nature, fattening was a response to food scarcity, with animals storing energy as fat to survive periods when resources were in short supply.

Humans were "no different", often responding to economic insecurity in the same way.

In future, New Zealand government policies which aimed to improve worker's sense of security and their enjoyment of work could be used to help in "curbing obesity rates".

Such new policy steps could include encouraging worker representation on company boards, which had already proved successful in Germany, he said.