Overweight and obese New Zealanders are costing the country between NZ$722 million and 849 million($602.82 million and $708.86 million) each year in health care costs and lost productivity, according to a study published Tuesday.

"These figures represent a major drain on health resources and point to a need to increase efforts on prevention," researcher Professor Boyd Swinburn, of the School of Population Health at Auckland University, said in a statement.

An estimated 35 percent of New Zealand aged over 15 were overweight and 25.4 percent were obese, according to the study.

Obesity has been well established as a key risk factor for major chronic illnesses such as cardiovascular diseases, type two diabetes and some cancers.

Health care costs, amounted to NZ$624 million, or 4.4 percent of national health care expenditure.

Costs of lost productivity, through absenteeism, premature death, or recruitment and training of replacement staff, were estimated to be between 98 million and NZ$225 million.

"These figures demonstrate a substantial loss of productivity, even without taking account of the costs which were not included - such as foregone taxes, costs of disability, and loss of well- being and quality of life," Auckland University researcher Professor Toni Ashton said in the statement.

A comparison with neighboring Australia showed both countries performed poorly on policies such as reducing junk food marketing to children, simple front-of-pack labeling on processed foods and giving the food industry too much influence in developing public policies.

However, Australia, as part of its national push to increase productivity, had invested heavily in programs to reduce obesity in workers, children and communities, and it "clearly outperformed New Zealand" by investing in community, school and workplace programs and by not having a consumption tax on fruit and vegetables.

The study was based on 2006 figures, and a previous study based on figures from 1991 estimated the health care costs of obesity alone in New Zealand at NZ$135 million.

"The prevalence of obesity has increased by more than 10 percent since the last published estimate, and additional diseases have been identified as being attributable to obesity," said Ashton.