健康：肥満の増加は低所得国でより急速に進んでいる

Obesity trends have continued to rise in low- and middle-income countries over the past 45 years, but have plateaued in many high-income countries, a study in Nature reports. The findings, based on a large-scale analysis of data from 232 million individuals across 200 countries and territories, show that considering obesity as a global epidemic hides the fact that trajectories differ substantially between countries, age groups and sex.

Obesity is more prevalent now than it was at the end of the twentieth century, and the term ‘epidemic’ has been used to describe its rise. However, the factors driving obesity such as quality and quantity of food and nutrition, vary across countries and over time. Understanding the detailed trajectories may help to identify relevant interventions and policy changes needed to address obesity in different countries.  

The NCD Risk Factor Collaboration, a network of nearly 2,000 scientists across the world, examined how the prevalence of obesity has changed between 1980 and 2024 in 200 countries and territories, using data from 4,050 population-based studies that measured height and weight of 232 million participants who were aged 5 years or older. Majid Ezzati and colleagues find that for almost all countries, obesity rates have increased over the study period, but trends have varied in different populations.  

In high-income countries, such as in Western Europe, North America and Australasia, obesity trajectories increased at the beginning of the study period, but have since plateaued in most, although obesity prevalence varies. For example, in different countries in Western Europe, obesity prevalence has stabilised at 11–23% for adults and 4–15% for children and adolescents. Other high-income countries, such as Japan, had a less steep increase and plateaued at lower prevalences, especially for women. The earliest slowdown occurred around 1990 in Denmark for both sexes, followed by some other European countries including Iceland, Switzerland, Belgium, and Germany through the 1990s.

By contrast, the rise of obesity has increased sharply in some low- and middle-income countries, reaching a prevalence of 30–40% among adults in some countries in Central Europe (for example, Romania and Czechia) and Latin America (such as Brazil). Variation was also observed between age groups and sex. In adults, the rise in obesity slowed down in high-income western countries about a decade after children. Differences between male and female individuals, such as whether or when obesity plateaued, were country dependent.

Identifying the different trends may help to explain the underlying factors, which could inform programmes or policies to address and curb the rise of obesity, the authors conclude. 
 

• Article
• Open access
• Published: 13 May 2026

NCD Risk Factor Collaboration (NCD-RisC). Obesity rise plateaus in developed nations and accelerates in developing nations. Nature 653, 510–518 (2026). https://www.nature.com/articles/s41586-026-10383-0

News & Views: Obesity has risen in all countries — but at a faster pace in poorer ones
https://www.nature.com/articles/d41586-026-00909-x