New Zealand is the third fattest nation in the developed world, a report has found.

The obesity rate among adults in New Zealand in 2007 was 26.5 per cent with only the United States at 34.3 per cent and Mexico at 30 per cent higher, the Organisation of Economic Co-operation and Development (OECD) Health Data Report 2009 released this month said.

Obesity rates had increased in all 30 OECD countries in recent decades, which may well lead to higher health care costs in the future, it said.

Green Party Health spokeswoman Sue Kedgley said the report highlighted the "stupidity" of the Government cutting funding for nutrition programmes and scrapping regulations banning junk food in school cafeterias.

"It's alarming that New Zealand has the third highest obesity rate and what's even more alarming is that the Government is doing nothing about it.

"They have even axed reducing obesity and improving nutrition targets for District Health Boards."

The Government needed to "take its head out of the sand" because preventing illness would save money in the long term, Ms Kedgley said.

Health Minister Tony Ryall said the Government took obesity very seriously.

The previous government was focused on nutrition but the current Government would take a more balanced approach, he said. It would be announcing a "greater role for physical activity and sports programmes".

"New Zealanders are less physically active then they were," Mr Ryall said.

"The Government wants a greater balance between healthy eating and healthy action."