Two million New Zealanders will be obese in 20 years' time, new research reveals.
A University of Otago report published today in the Australian and New Zealand Journal of Public Health showed the average body mass index (BMI) of New Zealanders increased from 26.4kg/m2 in 1997 to 28.3kg/m2 in 2015.
If the trend continued, New Zealand's average BMI would exceed the obesity threshold of 30kg/m2 by the early 2030s.
BMI is a measure of body fat based on height and weight in adults.
Between 18.5kg/m2 and 25kg/m2 is considered the healthy weight range, and 30kg/m2 or above is considered obese.
In 2015, 1.1 million New Zealanders were considered clinically obese but by 2038 that could be two million.
The prevalence of obesity in New Zealand had already trebled to 30% between 1977 and 2013, making it the third-most obese nation.
Researchers Dr Ross Wilson and Prof Haxby Abbott from the university's Centre for Musculoskeletal Outcomes Research at the Dunedin School of Medicine said the Government needed to take action to address the situation.
Dr Wilson said the Otago study revealed ''scary numbers'', which were ''very serious'' and could impose massive pressures on the health system and greatly increase health problems.
But this was ''definitely not'' the time to panic.
''There are things that can be done, that are likely to be effective'' and a ''broad, comprehensive approach'' was needed to counter these problems, he said in an interview.
But the researchers emphasised positive health gains had been made over smoking-related illness, by taking robust and comprehensive measures.
Unless countered by improved public health policies, continuing BMI increases were likely ''to increase the premature mortality, population health loss, healthcare system costs and workplace productivity losses'' linked to the obesity epidemic, they warned.
New Zealand's tobacco control measures already showed what could be achieved through comprehensive reforms, including taxation, advertising restrictions, and product regulation, in halting the spread of a public health epidemic.
High BMI had overtaken tobacco as the ''greatest contributor to health loss'' in New Zealand, he said.
A comprehensive obesity reduction strategy could include improving the ''relative affordability of healthy foods'', such as through taxation and subsidies, and ''restrictions on marketing of unhealthy foods'' and promotion of active forms of travel, including walking and cycling.
Our BMIs had risen significantly in recent decades, and New Zealand had among the highest prevalence rates of ''overweight'' and obesity among developed countries.
The study considered potential influences on obesity from the data of 76,294 adult New Zealanders.
