Overweight and obesity among adults

Being overweight, including pre-obesity and obesity, is a major risk factor for various non-communicable diseases including diabetes, cardiovascular diseases and certain cancers. High consumption of calories-dense food and increasingly sedentary lifestyles have contributed to growing global obesity rates. The rate of growth has been highest in early adulthood and has affected all population groups, in particular women and those with lower levels of education (Afshin et al., 2017_[1]). High body mass index (BMI) has been estimated to cause 4.7 million deaths worldwide (Global Burden of Disease Collaborative Network, 2018_[2])

Based on measured data, 58% of adults were overweight or obese in 2017 on average across 23 OECD countries with comparable data (Figure 4.11). For Chile, Mexico and the United States this figure exceeds 70%. Conversely, in Japan and Korea, less than 35% of adults were overweight or obese. The remaining 13 OECD countries include self-reported data, with rates ranging from 42% in Switzerland to 65% in Iceland. These estimates, though, are less reliable and typically lower than those based on measured data. For both measured and self-reported data, men are more likely than women to be overweight.

The proportion of overweight adults has been gradually increasing in most OECD countries since the early 2000s, including in countries where rates are relatively low (Figure 4.12). In Japan and Korea, this proportion has increased by 2.1 and 4.2 percentage points, respectively, between 2000 and 2017. In countries with relatively high rates of adults overweight, this figure ranged from 2.3 percentage points in Canada to 11.9 in Chile.

Adults with a low level of education are more likely to be overweight than those with a tertiary education level or above in all 27 OECD countries examined (Figure 4.13). The difference in the proportion of overweight adults by education level was greatest in Luxembourg, Spain and France, where the gap was greater than 15 percentage points.

OECD member countries have implemented a suite of regulatory and non-regulatory initiatives to reduce overweight population rates. Prominent examples include mass media campaigns to promote the benefits of healthy eating; promotion of nutritional education and skills; ‘sin’ taxes on energy-dense food and drink items to discourage consumption; food labelling to communicate nutritional value; and agreements with the food industry to improve the nutritional value of products. Policymakers are also exploring initiatives that address the social determinants of being overweight. For example, the Healthy Food Financing Initiative in the United States aims to improve access to healthy foods in underserved areas. Despite these efforts, the overweight epidemic has not been reversed, highlighting the issue’s complexity (OECD, 2019_[3]).

Definition and comparability

Overweight is defined as abnormal or excessive accumulation of fat, which presents a risk to health. The most frequently used measure is 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 WHO classifications, adults over age 18 with a BMI greater than or equal to 25 are defined as pre-obese, and those with a BMI greater than or equal to 30 as obese. Data come from national sources – in a few instances these may differ from data shown in the OECD 2019 report on obesity, which uses data from the WHO Global Health Observatory, with age-standardised estimates and other methodological differences. Overweight includes both pre-obesity and obesity. BMI measurements are the same for both genders and adults of all ages. Data for BMI can also be collected using self-reported estimates of height and weight. BMI estimates based on self-reported data are typically lower and less reliable than those based on measured data.

For Figure 4.13, the lowest level of education refers to people with less than a high-school diploma, while the highest refers to people with a university or other tertiary diploma.

References

[1] Afshin, A. et al. (2017), “Health Effects of Overweight and Obesity in 195 Countries over 25 Years.”, The New England Journal of Medicine, https://doi.org/10.1056/NEJMoa1614362.

[2] Global Burden of Disease Collaborative Network (2018), Global Burden of Disease Study 2017 (GBD 2017) Results, Seattle, United States: Institute for Health Metrics and Evaluation (IHME).

[3] OECD (2019), The Heavy Burden of Obesity: The Economics of Prevention, OECD Publishing, Paris, https://doi.org/10.1787/67450d67-en.

Figure 4.11. Overweight including obesity among adults by sex, measured and self-reported, 2017 (or nearest year)

Note: Left- and right-hand side estimates utilise measured and self-reported data, respectively. OECD36 average includes both data types.

Source: OECD Health Statistics 2019.

 StatLink https://doi.org/10.1787/888934015467

Figure 4.12. Evolution of overweight including obesity in selected countries, measured, 2000-17 (or nearest year)

Note: Linear interpolation was used to impute values where data was missing.

Source: OECD Health Statistics 2019.

 StatLink https://doi.org/10.1787/888934015486

Figure 4.13. Difference in overweight including obesity by education level, self-reported, 2014

Source: EHIS2 and OECD estimates based on national health survey data.

 StatLink https://doi.org/10.1787/888934015505