LONDON — A global study led by Majid Ezzati, professor of global environmental health, found that obesity prevalence increased in almost all countries between 1980 and 2024, but the rise has slowed, plateaued, or potentially reversed in most high-income nations. The research drew on 4,050 population-based studies involving 232 million participants aged five years and above, with a network of nearly 2,000 researchers calculating annual change in obesity prevalence for each country.

The team found that obesity trends vary by country, sex, and age group. "The thing that's really important is this diversity exists even across countries that have really similar economic, environmental, technological features. So countries may look the same on the surface but obesity looks different," Ezzati said.

Among adults in 2024, obesity prevalence reached 40-43% in the United States and 27-30% in the United Kingdom. In Finland, the rate stood at 24-25% and was increasing steadily, while Germany recorded 20-23% with a plateau. France registered 11-12%, a level that may have started to decline.

For children and adolescents, the slowdown began as early as 1990 in Denmark, and rates stabilized across most high-income countries by the mid-2000s. Obesity prevalence among boys and girls reached 20-23% in the U.S., 10-12% in the U.K., 7-12% in Germany, and 3-7% in Japan.

In many low-income and middle-income countries, obesity among young people and adults continues to rise and in some cases is accelerating. The research team identified easy access to unhealthy foods, decreased physical activity, perceptions around body image, and the presence or absence of interventions such as healthy school meals as potential factors influencing the trends.

Naveed Sattar, professor of metabolic medicine, said the rapid rise in obesity across many developing countries could result in increases in diabetes and cardiovascular conditions. "Looking ahead, it will be important to see how wider use of effective weight-loss medicines affects obesity trends, particularly in the UK and the United States. Recent signs of stabilisation in the USA suggest there may be room for cautious optimism. Combining evidence-based medicines with strong public health measures could begin to shift obesity rates in the right direction." Sattar said.