‘Obesity epidemic’ splits the world in two: Slowing in rich countries, surging in poorer ones
A study shows obesity trends have diverged across regions over the past four decades, though it is too early for drugs such as Ozempic to have had a measurable impact
For 40 years, the world has been under the grip of a “global obesity epidemic” — a surge in excess weight that raises the risk of developing cancer, cardiovascular, metabolic, and neurological diseases. The scientific community coined the term “epidemic” in the 1990s in response to the rising prevalence of obesity, and it has persisted ever since to describe what is now considered one of the major threats to global health. The World Health Organization (WHO) calls it “globesity.”
The idea of a non-infectious pandemic spreading inexorably across the globe has taken hold in the public imagination, but new research published on Wednesday in Nature, one of the world’s leading scientific journals, tempers that view somewhat and offers a glimmer of optimism. The study finds that while obesity is more widespread today than at the end of the 20th century, its growth has slowed — or even reversed in recent years — in the world’s wealthier regions. In poorer countries, however, it continues to rise sharply.
The finding that obesity is following different paths across the world provides a ray of hope in the face of this global threat. “This offers a more optimistic picture that progress is being made and challenges the widely accepted view that we’re experiencing a global epidemic of obesity — which may be an oversimplification of the diversity of the situation in different countries,” said Majid Ezzati, a researcher at Imperial College London and lead author of the study, in a statement.
The scientists argue that the trend towards obesity “is not inevitable” and attribute the slowdown of the epidemic in wealthier countries to a mix of social, economic, and technological factors affecting access to different types of food. As for the emergence of breakthrough weight loss drugs such as Ozempic, the authors believe they are too recent to have influenced trends so far, but expect them to play an important role in the future trajectory of obesity prevalence.
According to the study, which analyzed data from 232 million people in 200 countries between 1980 and 2024, obesity levels have moved across the world at different speeds over the past 45 years. In the 1980s, the prevalence of the condition began to rise in high-income countries and then spread globally — but at varying rates and intensities, producing highly uneven patterns.
Before the turn of the millennium, for example, obesity rates among children were increasing in high-income countries, but that trend has since slowed, stalled, and in some cases even reversed. Denmark was the first country to curb the trend in the early 1990s, followed by Iceland, Switzerland, Belgium, and Germany. By the mid-2000s, the rise in childhood obesity had levelled off in much of the wealthy world. Only Australia, Finland, and Sweden recorded sustained and persistent increases in childhood obesity.
Improvements in high-income countries were first seen in children and, roughly a decade later, in adults — earlier among women than among men. The authors note that by 2024, in some countries, such as Spain and Italy, the growth rate of adult obesity had turned negative, meaning the condition was in decline.
For Albert Goday, an endocrinologist at Barcelona’s Hospital del Mar, the study offers “a glimmer of light at the end of the tunnel of the obesity pandemic,” though he cautions against complacency: “We can see that the relentless rise in obesity has eased in some regions. But can we relax because the epidemic is under control? No. If that were the takeaway, we’d be making a mistake… prevalence remains very high,” he warns. According to Spain’s Health Ministry, 15% of adults and 7% of children in Spain are obese.
The Nature study also emphasises that, even within these declining trends, wealthy countries have slowed the rise in obesity at very different levels. In Western Europe and Japan, stabilization or reversal occurred with prevalence rates of between 4% and 15% among children and 11% to 23% among adults. By contrast, in English-speaking high-income countries such as the United States and New Zealand, the plateau came at much higher levels, with adult obesity affecting between 25% and 43% of the population and childhood obesity ranging from 7% to 23%.
This plateau — or even reversal — in the rate of obesity growth has been common across rich countries, but not universal: the study shows that prevalence has continued to rise over the past 45 years among both sexes in Finland, and among women in Norway and Belgium.
Widening inequality
The research nonetheless highlights a growing disparity that shows no sign of narrowing. Despite the more encouraging trends in wealthier countries, obesity has continued to climb in poorer regions over the past 45 years. In fact, in 2024, the rate of increase in obesity reached record highs among women in 84 countries and among men in 109 — almost all of them in low- and middle-income regions.
Camille Lassale, a researcher at ISGlobal, says the study captures the “epidemiological transition” now unfolding worldwide. “Countries with lower and middle incomes are beginning to face the same problems as wealthier nations,” she explains. This shift is closely linked to globalization and to lifestyle changes that increasingly reflect Western patterns — from diet to physical activity.
Even within poorer countries, the sharp rises in obesity are occurring in very different contexts and from highly varied starting points. In 2024, for instance, obesity rates in East African countries such as Ethiopia and Rwanda remained below 5%, while in parts of Central Europe, such as Romania, and in Latin America, prevalence ranged between 30% and 40%. In all these regions, obesity was rising, but from very different baselines.
The authors argue that traditional explanations for the rise in obesity — such as food availability, physical activity at work, leisure habits or urbanization — “may be relevant, [but] they alone do not explain the heterogeneities that we uncovered.” They also point to the influence of other social, economic, and political factors, as well as cultural aspects and social norms, including perceptions of body image and the gap between ideal, actual, and perceived weight. The researchers also note that income levels and their distribution, along with education, shape food choices and participation in sports.
The impact of anti-obesity drugs such as Ozempic is assumed to be limited or negligible in this analysis, which runs up to 2024, when access to these treatments was still fairly restricted. Looking ahead, however, the authors argue that these medications “provide an additional route for addressing obesity, but their highly variable costs through public and private providers are currently an obstacle to increasing their coverage and may increase inequalities.”
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