Scientists found that obesity among school-aged children and adolescents increased in nearly every country over the past four decades. But while some high-income countries are beginning to slow the pace of obesity growth, many developing regions across Asia, Africa, Latin America and the Pacific Islands are now experiencing some of the fastest increases recorded since 1980.
Childhood and adolescent obesity is rising fastest in low- and middle-income countries, even as growth rates begin to stabilise or slightly decline across many wealthier nations, according to a major new global study published in Nature.
The research, released on May 13, 2026, analysed obesity trends from 1980 to 2024 using data from 4,050 population-based studies involving 232 million participants across 200 countries and territories.
Scientists found that obesity among school-aged children and adolescents increased in nearly every country over the past four decades. But while some high-income countries are beginning to slow the pace of obesity growth, many developing regions across Asia, Africa, Latin America and the Pacific Islands are now experiencing some of the fastest increases recorded since 1980.
Researchers warn that the accelerating obesity crisis is being driven by rapid urbanisation, changing diets, rising consumption of ultra-processed foods and declining physical activity, creating growing risks for diabetes, cardiovascular disease and other serious health conditions.
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Obesity Growth Slows in High-Income Countries
The study found that many high-income countries experienced their sharpest increases in childhood obesity before 2000.
Since then, obesity growth rates among children and adolescents have slowed substantially, stabilised or in some cases slightly declined across parts of Western Europe, North America, Australasia, Japan and Taiwan.
Countries including Denmark, France, Switzerland and the Netherlands recorded very low or near-zero annual increases over the past decade.
Researchers also identified indications that obesity growth may have turned slightly negative in countries such as France, Italy and Portugal.
The study noted that obesity prevalence among children and adolescents now spans a wide range even within developed nations, from relatively low levels in Japan, Denmark and France to much higher rates in the United States.
Among boys in the United States, obesity prevalence reached around 23 per cent, according to the analysis.
Scientists said these changing patterns may reflect evolving food systems, public health interventions and broader social and economic trends influencing diet and lifestyle in wealthier societies.
Developing Countries Face Fastest Rise in Childhood Obesity
While obesity growth appears to be slowing in some developed economies, the study found that the trend continues to intensify across much of the developing world.
By 2024, obesity growth rates were at their highest levels since 1980 in 110 countries for girls and in 91 countries for boys, with most of those countries classified as low- and middle-income economies.
Researchers recorded rapid increases even in countries where overall obesity prevalence remains relatively low, including Tanzania, Rwanda, Ethiopia, Nepal and Bangladesh.
At the same time, obesity rates had already climbed to high levels in several regions, including Caribbean and Pacific Island nations such as Niue and the Bahamas, Middle Eastern countries including Saudi Arabia, Qatar and Oman, Southeast Asian nations such as Brunei and Malaysia, and parts of Latin America including Chile.
The findings suggest that obesity is no longer primarily a high-income country problem, but increasingly a major public health challenge for developing economies undergoing rapid social and economic change.
Urbanisation and Ultra-Processed Foods Drive New Health Risks
Scientists involved in the study said multiple interconnected factors are contributing to the accelerating obesity crisis in developing regions.
Rapid urbanisation, changing food environments, increased access to ultra-processed foods and declining levels of physical activity are all reshaping lifestyles across many countries.
Researchers said these transformations are occurring faster than public health systems and policy frameworks can adapt.
The study noted that while high-income countries may have benefited from policies and broader social shifts that helped slow obesity growth, similar interventions remain limited or insufficient across many lower-income nations.
Scientists warned that without stronger policy responses, obesity rates are likely to continue rising across vulnerable populations.
Researchers Examine Obesity Trends Across 44 Years
The study stands out for its scale and detailed analysis of obesity trends over time.
Unlike earlier reports that compared obesity prevalence over broad periods, researchers examined annual changes in obesity prevalence using a measurement known as velocity, which tracks yearly percentage-point increases.
Adult obesity was defined as a body mass index of 30 kilogrammes per square metre or higher, while obesity among children and adolescents was measured using World Health Organization growth standards.
The researchers found that obesity prevalence among school-aged children and adolescents increased by between 0.6 and 27 percentage points among girls and between 0.4 and 35 percentage points among boys between 1980 and 2024.
The study also observed similar patterns among adults, with obesity growth in many high-income countries slowing roughly a decade after childhood obesity trends began stabilising.
Some countries, including Spain, may even be showing early signs of a plateau or slight reversal in adult obesity growth.
Health Experts Warn of Long-Term Consequences
Scientists cautioned that obesity is associated with a broad range of serious health risks, including cardiovascular disease, diabetes, respiratory illness, liver disease, kidney disease and certain cancers.
The health burden is expected to become especially significant in countries where healthcare systems are already under pressure.
Researchers also warned that obesity trends among children and adolescents could translate into rising chronic disease burdens later in life, increasing economic and healthcare costs for governments worldwide.
The study’s findings highlight growing inequalities in global health, as many developing nations now face a dual challenge of undernutrition and rising obesity simultaneously.
Global Obesity Patterns Reflect Broader Social Change
Researchers said the varied obesity dynamics observed across countries reflect deeper transformations in food systems, lifestyles and urban development.
The study concluded that the same social, economic and technological trends that may have helped slow obesity growth in wealthier countries now require targeted policy intervention across low- and middle-income nations.
Scientists stressed that the obesity crisis cannot be addressed through healthcare alone, and will likely require broader strategies involving food systems, urban planning, education and public health policy.
As childhood obesity continues to accelerate across many parts of the developing world, researchers say the challenge is no longer whether obesity is a global epidemic, but how quickly countries can adapt before the long-term health consequences become even more severe.
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