Question and Answer

Obesity in New Zealand
Questions and answers

What is obesity?
Obesity is defined as an excessively high amount of body fat (adipose tissue) in relation to lean body mass. Overweight is excess weight for height.

How is obesity measured?
Body mass index (BMI) is commonly used to classify adults as overweight and obese. BMI is a measure of weight adjusted for height and is calculated by dividing weight in kilograms by height in metres squared (kg/m2).

Obesity is defined as:

BMI greater than or equal to 30.0 for all New Zealand adults

Overweight is defined as:

BMI 25.0 to 29.9 for all New Zealand adults

Previously there has been higher BMI cut offs for Pacific and Māori peoples, however the Ministry of Health has adopted World Health Organization international recommendations which do not recommend ethnic-specific cut off points.

For more information about this, refer to the Body Size Technical Report.

Why are overweight and obesity a problem?
Overweight and obesity are risk factor for most serious chronic diseases, including type 2 diabetes, ischaemic heart disease (IHD), stroke and several common cancers.

The impact of excess body weight on these diseases operates, at least in part, through its effects on insulin resistance, blood glucose, blood lipids and blood pressure.

In an earlier (2003) study carried out jointly by the Ministry of Health and the University of Auckland, higher than optimal BMI was estimated to contribute to approximately 3200 deaths in New Zealand in 1997, mostly through type 2 diabetes, IHD and stroke. This burden will be even higher today given that the mean BMI of the adult population has increased since 1997.

What causes overweight and obesity?
Overweight and obesity are the result of a positive energy balance - that is, a chronic excess of energy intake (food and beverage consumption) over energy expenditure (physical activity).

Although some people are more genetically susceptible to weight gain than others, the rapid increase in the prevalence of obesity in recent years has occurred too quickly to be explained by genetic changes and most experts believe it is due to living in an increasingly ‘obesogenic’ environment – one that promotes over-consumption of food and drinks and limits opportunities for physical activity.

How many New Zealand adults are overweight or obese?
1,128,500 New Zealand adults are overweight and 826,100 are obese.

What is the Ministry of Health doing about obesity?
Reducing obesity is one of the priority objectives in the New Zealand Health Strategy, along with improving nutrition and increasing physical activity. These three objectives have been combined into the Healthy Eating - Healthy Action Strategy.

The HEHA strategy recognises that it will take multiple actions by multiple players over many years to change the environment so that healthy choices are the easy choices.
In recognition of this, the HEHA Implementation Plan 2004 - 2010 was developed in partnership with other central government agencies, health-related non-government organisations, academia and industry. This is currently under review and will be completed in 2009.

Where has the latest obesity data come from?
Latest obesity figures were released in June 2008 in A Portrait of Health: Key Results from the 2006/07 New Zealand Health Survey.