Obesity rates have continued to rise rapidly across many low- and middle-income countries over the past four decades, while growth has slowed or stabilised in much of Western Europe and other wealthy nations, according to a major international study published in Nature.
The research examined data from 232 million people across 200 countries and territories between 1980 and 2024, making it one of the largest studies ever conducted on global obesity trends. Researchers involved in the project said the findings challenge the idea of obesity as a single worldwide epidemic, arguing instead that patterns differ widely depending on country, age group and sex.
The study was carried out by the NCD Risk Factor Collaboration, which includes nearly 2,000 scientists from around the world. Researchers analysed more than 4,000 population-based studies measuring height and weight among people aged five and older.
Using the World Health Organization definition of obesity, adults with a body mass index, or BMI, of 30 or above were classified as obese. For children and teenagers, obesity was measured using age- and sex-adjusted WHO growth standards.
The findings showed that in many high-income countries, particularly in Western Europe, North America and Australasia, childhood obesity rates began slowing during the 1990s and had largely levelled off by the mid-2000s. Some countries have even started to record slight declines.
Denmark was among the first nations where childhood obesity rates stabilised around 1990. By the 2010s, countries including France, Italy and Portugal were seeing modest reductions in childhood obesity, something researchers described as a significant development.
Adult obesity trends followed a similar path roughly a decade later. In much of Western Europe, adult obesity rates in 2024 remained below 25 percent, with France recording levels as low as 11 percent. That contrasts sharply with English-speaking high-income countries such as the United Kingdom, Canada and the United States, where adult obesity rates ranged between 25 percent and 43 percent.
The situation in developing nations appeared far more alarming. Across sub-Saharan Africa, South and Southeast Asia, Latin America and Pacific Island states, obesity rates continued climbing steadily, with some countries experiencing accelerating increases.
Researchers found the fastest growth rates among girls in Tonga and Samoa and among boys in Peru. In Tonga and the Cook Islands, more than 65 percent of adults are now classified as obese.
The study also highlighted rising obesity levels in countries where the condition had once been relatively uncommon, including Ethiopia, Rwanda and Bangladesh.
Researchers said the differing trends were shaped by several factors, including access to ultra-processed foods, physical activity levels, income, healthcare systems and government policies. Measures such as sugar taxes were identified as among the few interventions that had shown measurable effects at a population level.
The report warned that without stronger and more targeted policies, many developing countries could face long-term pressure on healthcare systems as obesity rates continue to climb.
