ObesityDefinitionThe proportion of the population aged 15 and over who are obese. Obesity is defined as having a Body Mass Index (BMI) greater than 30 for European/Other ethnicities, or greater than 32 for Māori and Pacific peoples.28 For the population aged under 15, the measure is the proportion of children aged 5–14 years whose BMI met internationally defined thresholds of obesity.29 RelevanceObesity is associated with heart disease, diabetes, stroke, high blood pressure and some cancers. The increase in the prevalence of obesity has been identified as a major cause of the projected increase in diabetes.30 Current level and trendsIn 2003, 21 percent of adults aged 15 and over were obese, an increase from 17 percent in 1997. In 2002, 10 percent of children aged 5–14 years were obese. The prevalence of obesity among New Zealand adults aged 15–74 years doubled between 1977 and 2003, from 9 to 20 percent in males and from 11 to 22 percent in females.31 The major drivers of the increase in obesity rates have been changing dietary and physical activity patterns, reflecting an environment that promotes the over-consumption of energy-dense foods and drinks and limits opportunities for physical activity.32 Figure H5.1 Prevalence of obesity, total population aged 15–74 years, by sex, 1977–2003
Source: Ministry of Health (2004b) Table 19, p89 Age and sex differencesAge-standardised prevalence rates for 2003 showed no significant sex difference in the proportion of adults who were obese (males, 19 percent; females, 21 percent). Obesity increased with age up to the 55–64 year age group (males, 29 percent; females, 31 percent), then declined in the older age groups. This age pattern may reflect in part a cohort effect.33 Among children aged 7–14 years in 2002, females were more likely than males to be obese. Table H5.1 Prevalence (%) of obesity, population aged 15 and over, by age group and sex, 2003
Source: Ministry of Health (2004a) pp85–86 Ethnic differencesObesity is more prevalent among Pacific peoples and Māori than other ethnic groups. Among adults in 2002/2003, the age-standardised obesity prevalence rate was 48 percent for Pacific females and 38 percent for Pacific males. For Māori adults, the figures were 28 percent for females and 29 percent for males. This compares with 20 percent for European/Other females and 18 percent for European/Other males. Among children aged 5–14 in 2002, there was a similar pattern (Pacific children: 31 percent and 26 percent for females and males respectively; Māori children: 17 percent, 16 percent; European/Other: 6 percent, 5 percent). Figure H5.2 Age-standardised prevalence of obesity, population aged 15 and over, by ethnic group and sex, 2002/2003
Source: Ministry of Health (2004a) Tables 13 and 14, pp103–104 Obesity levels have been increasing over time, but from 1997 to 2003 among the Māori population there was a substantial slowing of the rate of change, compared to the total population. The prevalence of obesity for Māori males remained steady over the period at approximately 27 percent and there was a slight decline for Māori females, from 27.9 to 26.5 percent. Between 1997 and 2003 the obesity rate for the total population increased for both males (from 15 to 20 percent) and females (from 19 to 22 percent). Socio-economic differencesThe association between socio-economic status and female obesity has been found consistently over time and using different measures of socio-economic status. For example, in 2003, while 28 percent of females living in quintile 5 small areas (the most disadvantaged fifth of small areas in New Zealand ) were obese, only 16 percent of those in quintile 1 were obese. However, the link between male obesity and socio-economic status is less well-established.34 International comparisonNew Zealand has a relatively high prevalence of obesity compared with other OECD countries, with a rate of 21 percent in 2003, compared to an OECD median of 13 percent. New Zealand ranked poorly at 22nd out of 27 countries reporting obesity prevalence in 1999–2003. However, only three other countries base their estimates on actual measurements and New Zealand ranked better than these: the United States (with the worst rate of obesity, at 31 percent in 2002); the United Kingdom (22 percent in 2002) and Australia (22 percent in 1999). Of all countries, Korea had the lowest prevalence of obesity (3 percent in 2001).35 |
