The rise in overweight and obesity is a major public
health concern. Obesity is a known risk factor for numerous health problems, including
hypertension, high cholesterol, diabetes, cardiovascular diseases, respiratory
problems (asthma), musculoskeletal diseases (arthritis) and some forms of cancer. At
an individual level, several factors can lead to obesity, including excessive calorie
consumption, lack of physical activity, genetic predisposition and disorders of the
Because obesity is associated with higher risks of
chronic illnesses, it is linked to significant additional health care costs. There is
a time lag between the onset of obesity and related health problems, suggesting that
the rise in obesity over the past two decades will mean higher health care costs in
the future. Mortality also increases sharply once the overweight threshold is crossed.
Overweight and obesity are defined as excessive
weight presenting health risks because of the high proportion of body fat. The most
frequently used measure is based on the body mass index (BMI), which is a single
number that evaluates an individual's weight in relation to height
(weight/height2, with weight in
kilograms and height in metres). Based on the WHO classification, adults with a BMI
between 25 and 30 are defined as overweight, and those with a BMI over 30 as
The BMI classification may not be suitable for all
ethnic groups, who may be exposed to different levels of health risk for the same
level of BMI. The thresholds for adults are also not suitable to measure overweight
and obesity among children.
For most countries, overweight and obesity rates are
self-reported through estimates of height and weight from population-based health
interview surveys. However, around one-third of OECD countries derive their estimates
from health examinations. These differences limit data comparability. Estimates from
health examinations are generally higher and more reliable than from health
The following countries use measured data: Australia,
Canada, Chile, the Czech Republic, Finland, Ireland, Japan, Korea, Luxembourg, Mexico,
New Zealand, the Slovak Republic, the United Kingdom and the United States.
Based on latest available surveys, more than half
(50.3%) of the adult population in the OECD report that they are overweight or
obese. Among those countries where height and weight were measured, the proportion
was even greater, at 55.8%. The prevalence of overweight and obesity among adults
exceeds 50% in no less than 19 of 34 OECD countries. In contrast, overweight and
obesity rates are much lower in Japan and Korea and in some European countries
(France and Switzerland), although even in these countries rates are increasing.
The prevalence of obesity, which presents even
greater health risks than overweight, varies tenfold among OECD countries, from a
low of 4% in Japan and Korea, to 30% or more in the United States and Mexico.
Across the entire OECD region, 17% of the adult population are obese. Average
obesity rates among men and women are similar, although there are disparities
in some countries. In Chile, Turkey and Mexico, a greater proportion of women are
obese, whereas in the Russian Federation, Luxembourg and Spain men are more likely
to be obese.
Obesity prevalence has more than doubled over
the past 20 years in Australia and New Zealand, and increased by half in the
United Kingdom and the United States. Some 20-24% of adults in Australia, Canada,
the United Kingdom and Ireland are obese, about the same rate as in the United
States in the early 1990s. Obesity rates in many western European countries have
also increased substantially over the past decade. The rapid rise occurred
regardless of where levels stood two decades ago. Obesity almost doubled in both
the Netherlands and the United Kingdom, even though the current rate in the
Netherlands is around half that in the United Kingdom.
In most countries, the rise in obesity has
affected all population groups, regardless of sex, age, race, income or education
level, but to varying extents. Evidence from a number of countries (Australia,
Austria, Canada, France, Italy, Korea, Spain, the United Kingdom and the United
States) indicates that obesity tends to be more common among individuals in
disadvantaged socio-economic groups, especially women. There is also a
relationship between the number of years spent in full-time education and obesity,
with the most educated individuals displaying lower rates. Again, the gradient in
obesity is stronger in women than in men.