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What is Obesity?

What is the difference between being overweight and obese?

An adult is considered "overweight" when he/she is above what is considered a healthy weight for their height.  As healthy weight is directly related to an individuals height it varies for each person.

An individual is considered overweight when their "body mass index" or BMI is between 25-30. (BMI is the standard used to define a person's weight according to their height is).

An adult with a BMI of 30 or more is considered obese.

How do you calculate BMI?

BMI charts are available from the internet or it is easy to calculate.

To calculate your BMI, take your weight in kilograms and divide by your height in metre squared.

  __Weight kg___    =   BMI
    Height x Height

For Example: If you are 80kg and are 1.70m tall your BMI will be

__90___    =   31
 1.7 x 1.7

Other methods used to indicate levels of obesity include Weight to Hip Ratio (WHR) and waist circumference.

WHR is used as a measure of abdominal obesity, with a WHR in Caucasian men >1.0 and a WHR in women >85 indicating abnormal levels of fat accumulation.

Waist circumference is a simple tape measurement taken at the point level with the "belly button" and parallel to the ground, and is an approximate index of abdominal fat mass. Changes in waist measurement can be directly related to risks for heart disease and other chronic diseases. Waist circumference recommendations are <102 for men and <88cm for women.

Information released by the New Zealand Ministry of Health indicates:

  • In the New Zealand National Health Survey conducted in 1997 more than half of New Zealand adults were now overweight (35 percent) or obese (17 percent).
  • In a 2002 Children's Nutrition Survey showed that approximately one third of New Zealand children between the ages of 5-14 years was overweight (21 percent) or obese (10 percent). 
  • Obesity in New Zealand adults over 15 years of age increased from 11 percent in 1989 to 17 percent in 1997.
  • Provisional results of the 2002/03 New Zealand Health Survey indicate that one in five New Zealand adults were obese.
  • If current trends continue 29 percent of all adult New Zealanders are likely to be obese in 2011.
  • The 1997 National Nutrition Survey found that obesity rates among Mäori were 27 percent of Mäori men and 28 percent of Mäori women.
  • The same survey also found that 26 percent of Pacific men and 47 percent of Pacific women were obese. 75% of Pacific Island peoples in New Zealand are estimated to be overweight.
  • As we age, so does or risk of being overweight or obese. This is due to a combination of physiological factors and reduced physical activity.
  • While obesity in New Zealand is found in all socio-economic groups, a disproportionate high number is found in socio-economically disadvantaged groups.

What are the risks associated with obesity?
Obesity is a risk factor for many chronic diseases, including:
Type 2 diabetes
Heart disease
and some Cancers

More than 1,000 New Zealanders die each year from obesity-related diseases - double the annual road toll.

Obesity in New Zealand adults runs at a rate of approximately 17 per cent. While in France it is only 7 per cent. Statistics from New Zealand and Britain indicate that there are more than 200 deaths per 100,000 from heart disease each year, while in France there are 83 per 100,000.

Does childhood obesity influence adult obesity?
Childhood obesity may influence adult obesity and thereby increase the risk of obesity-related disorders, so the importance of achieving a healthy bodyweight during childhood cannot be underestimated. Similarly, problematic eating resulting in low energy intakes in childhood may lead to short and long-term problems with being underweight.

In addition to the risk of chronic disease in adulthood, obese children may suffer psychological and social pressures. Older children associate overweight body shape with poor social functioning, impaired academic success and reduced fitness and health.

Is there a link between obesity and genetics?
The risk of developing obesity is determined by both genetic and environmental factors. Whether a child becomes obese depends on their genetic susceptibility and the presence of environmental fattening stimuli, such as low social class, single parent families, single child families, excessive television viewing and inactivity.

Parental obesity is a strong predictive risk factor for childhood obesity. Parenting styles may influence the development of food preferences and the ability for the child to regulate intake.

Families serve as models, which reinforce and support the acquisition and maintenance of eating and exercise behaviour.

What can I do to reduce weight?
Long term and sustainable changes in eating and exercise patterns are the recommended to affect healthy weight loss and management for adults.

For children it is recommended that weight be maintained so that a child can grow into his or her ideal weight. Dieting children is not recommended.

Speak to your doctor and or a New Zealand registered dietitian regarding safe weight loss and exercise options that are suitable for you.

Does physical activity affect my weight?
Physical activity for both adults and children encouraged is encouraged. As food is the body's fuel source, any exercise or physical activity is going to help use up any excess fuel introduced or stored by the body.

What sort of goals should I set?
All dietary and physical activity goals need to be achievable.

It is important for eating patterns to be flexible. Variety means that you will not get bored, and therefore be less likely to seek unhealthy alternatives. For adults a 300-500g per week weight loss is recommended.

Exercise can be the most difficult part of a weight loss programme. Introducing exercise in small amounts and adding to the level of activity gradually is a great way to start. It helps avoid injury and unnecessary stress on the body.

The Ten Thousand Steps programme is a great way to start increasing the level of activity in your daily routine. Log onto for more information.

For more information on obesity in New Zealand Log onto: