The report, titled ‘Tracking the Obesity Epidemic’, compares New Zealanders' size from 1977 through to 2003.

It shows that the number of obese adults has doubled from 10 per cent of the adult population (aged 15 to 74) in 1977 to 21 per cent last year. An additional 900,000 adults were overweight.

Based on information from four national nutrition and health surveys, showed the epidemic grew relatively slowly in the 1970s and 1980s then accelerated rapidly in the late 1980s and 1990s.

Major reasons for the increase were changing diet and physical activity patterns, or what was referred to as an "obesogenic" environment that promoted over-consumption of energy-dense foods and drinks and limited opportunities for exercise.

Rates for Maori increased from 19.3 to 27 per cent in males and from 20 to 26.5 per cent in females.

Being overweight or obese puts people at greater risk of a number of conditions, including type 2 diabetes, heart disease and stroke. A Ministry of Health and Auckland University study estimated that about 3200 deaths each year were attributable to a higher than optimal body mass index (BMI).

Reducing obesity is a priority of the New Zealand Health Strategy.

GETTING BIGGER

*Mean Body Mass Index (BMI)

Adult males

1977: 25.5

2003: 26.9

Adult females

1977: 24.5

2003: 26.4

*Body Mass Index is measured by dividing weight in kilograms by height in metres squared. In New Zealand, obesity is defined as a BMI greater than or equal to 30 for European, Asian and other adults, or a BMI greater than or equal to 32 for Maori and Pacific adults.

OBESITY FIGURES

Adult males

1977: 9.4 per cent

2003: 19.9 per cent

Adult females

1977: 10.8 per cent

2003: 22.1 per cent