As a percentage of population aged 15 or more
*notes: Canada, United States: 2002 rather than 2003; Korea: 1981 rather than 1980; New Zealand: 2001 rather than 2002 and 2003; OECD Average: excludes Korea.

Obesity

Obesity is a known risk factor for several diseases such as diabetes, hypertension, cardiovascular disease, respiratory problems (asthma) and musculoskeletal diseases (arthritis). At an individual level, several factors can lead to obesity, including excessive calorie consumption, lack of physical activity, genetic predisposition and disorders of the endocrine system.

Because obesity is associated with higher risks of chronic illnesses, it is linked to significant additional health care costs.

Definition

The most frequently used measure of overweight and obesity is based on the body mass index (BMI), which is a single number that evaluates an individual’s weight status in relation to height (weight/height2, with weight in kilograms and height in meters). Based on the WHO current classification, individuals with a BMI between 25 and 30 are defined as overweight, and those with a BMI over 30 as obese.

Comparability

The BMI classification may not be suitable for all ethnic groups, who may have equivalent levels of risk at lower BMI (for example, Asians) or higher BMI. It is also not suitable to measure overweight and obesity among children.

For most countries, data on obesity are self-reported through population-based health interview surveys. The exceptions are Australia, Canada (2004), New Zealand, the United Kingdom and the United States, where the data are derived from health examinations whereby actual measures are taken of people’s height and weight. These differences in data collection methodologies seriously limit data comparability. Estimates from health examinations are generally higher and more reliable than those coming from health interviews.

Long-term trends

More than 50% of adults are now defined as either being overweight or obese in no less than 10 OECD countries: the United States, the United Kingdom, Mexico, Australia, Canada, Greece, New Zealand, Luxembourg, Hungary and the Czech Republic. By comparison, overweight and obesity rates are much lower in the OECD’s two Asian countries (Japan and Korea) and in some European countries (France and Switzerland), although overweight and obesity rates are also increasing in these countries. Focusing only on obesity, the prevalence of obesity among adults varies from a low of 3% in Japan and Korea to a high of 32% in the United States.

Based on consistent measures of obesity over time, the rate of obesity has more than doubled over the past twenty years in the United States, while it has almost tripled in Australia and more than tripled in the United Kingdom. The obesity rate in many Western European countries has also increased substantially over the past decade.

Gender differences are striking. In all countries, more men are overweight than women, but in just over half of OECD countries, more women are obese than men. Taking overweight and obesity together, the rate for women exceeds that for men in only two countries – Mexico and Turkey.

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Source

• OECD (2006), OECD Health Data 2006, OECD, Paris.

Further information

Analytical publications

• OECD (2004), The OECD Health Project: Towards High-Performing Health Systems, OECD, Paris.

Statistical publications

• OECD (2007), Health at a Glance: OECD Indicators, OECD, Paris.

Websites

• OECD Health Data, www.oecd.org/health/healthdata.


• Session on Obesity and Health at the OECD Forum 2004, www.oecd.org/forum2004.