Global obesity rise is not inevitable, research shows, as a major international study reveals that rates in some countries have started to level off or even decline, challenging the notion of an unstoppable worldwide epidemic.
The analysis, published in the journal Nature and led by a network of almost 2,000 researchers, drew on data from 4,050 population-based studies involving 232 million participants aged five and over. It calculated changes in obesity prevalence every year between 1980 and 2024 across virtually every country. While the prevalence of obesity increased in almost all nations over the 45-year period, the pattern was far from uniform. In most high-income countries, a rapid rise has given way to a slower increase, a plateau, or, in a few cases, a potential downturn.
Professor Majid Ezzati of Imperial College London, the study’s author, emphasised the striking diversity between nations. “The thing that’s really important is this diversity exists even across countries that have really similar economic, environmental, technological features,” he said. “So countries may look the same on the surface of it but obesity looks different.”
Country-level trends show a mixed picture
The research found that in the United States the rate of growth in obesity among adults is slowing, reaching a prevalence of 40–43% in 2024. According to further data, the US adult obesity rate has remained largely unchanged since 2020, following a 13.6% increase between 2010 and 2024, and some evidence points to a slight decrease of about 2% from 2020 to 2023. Severe obesity increased through 2021 but then trended downward through 2024. Adults aged 18–39 saw the greatest rise in median body mass index over the same period. Between August 2021 and August 2023, the overall adult obesity prevalence stood at 40.3%, with higher rates among those aged 40–59. Notably, 19 US states had obesity rates of 35% or higher in 2024, down from 23 the previous year, suggesting progress.
In the United Kingdom, the rate of growth is also slowing, with an adult obesity prevalence of 27–30% in 2024. Yet Professor Naveed Sattar of the University of Glasgow, who was not involved in the study, warned that English-speaking nations are “doing particularly poorly” and that the UK is now among the countries with the highest obesity levels worldwide. Separate figures show that in England, 64.5% of adults aged 18 and over were estimated to be overweight or living with obesity in 2023-2024, an upward trend since 2015-2016, and that 26.5% of adults in England were living with obesity in the same period. In Scotland, 66% of adults were overweight or obese in 2023-24, the highest proportion in the UK.
France presents a more encouraging picture: obesity may have started to decline, with an estimated 11–12% of adults affected in 2024. However, other sources suggest the rate is closer to 21.5%, and the Obepi-Roche study in 2020 found that 17% of French adults were obese, a doubling from 1997. Northern and eastern France have the highest rates, exceeding 20%, while the obesity rate among 18- to 24-year-olds has quadrupled, from about 5.4% to 9.2% in 2020.
In Germany, obesity has plateaued, with prevalence among adults rising from 12.2% in 2003 to 19.7% in 2023, and the World Obesity Atlas 2024 projects an annual increase of 0.5% between 2020 and 2035. Finland continues to see a steady increase. For children and adolescents, the slowdown began early: in Denmark, rates stabilised among young people as early as 1990, and by the mid-2000s most high-income countries had seen a plateau. In the UK, US, Germany and Japan, obesity has plateaued among boys and girls at levels of 10–12%, 20–23%, 7–12% and 3–7% respectively.
In stark contrast, many low- and middle-income countries are seeing obesity continue to rise among both young people and adults, and in some cases the increase is accelerating. Levels of overweight and obesity in these nations have approached those in richer countries, especially in the Middle East and North Africa, and Latin America and the Caribbean. Annual increases in overweight range from 0.31% in Latin America and the Caribbean to 0.92% in the Middle East and North Africa. Over two-thirds of women in North Africa and the Middle East are overweight or obese, followed by half of women in Latin America and the Caribbean. Remarkably, 62% of the world’s population with obesity now resides in low- and middle-income countries. Globally, obesity has surpassed one billion people, making it the most common form of malnutrition in most countries. An estimated 159 million children and adolescents were living with obesity in 2022, along with 879 million adults.
What drives the differences?
Unpicking the reasons behind these divergent trends is crucial, the researchers say. While shared drivers such as easy access to unhealthy foods and decreased physical activity play a role, country-specific factors rooted in social, economic and policy considerations may be equally important. In low- and middle-income countries, the shift from traditional diets to modern eating patterns, rapid urbanisation and increasingly sedentary lifestyles are accelerating the crisis. In developed countries, obesity is becoming more concentrated among poorer populations as economies grow. In Germany, people with lower socio-economic status are more frequently affected; in England, prevalence is highest in the most deprived areas and among Black and White British ethnic groups.
Body image perceptions also differ across cultures. Societal emphasis on thinness, particularly for women, contributes to body dissatisfaction, which can lead to disordered eating and psychological distress. Adolescent girls, in particular, experience more body dissatisfaction than boys, often perceiving themselves as overweight and aspiring to a slimmer physique.
Policy interventions have shown promise. Changes to school lunch programmes, such as the Healthy, Hunger-Free Kids Act in the US, which set stricter nutrition standards and reduced sodium and fat while increasing fruit and vegetables, may have reduced children’s likelihood of becoming overweight. Such programmes are considered a critical tool for student health, especially for children from low-income households.
Professor Sattar noted that understanding what has worked in countries that have reached a plateau is essential for shaping public health strategies in the UK. “Understanding what has worked in those settings is crucial as it could help shape more effective public health strategies for the UK,” he said, though he cautioned that there could be country-specific aspects or customs at play. He described the rapid rise in many developing countries as “especially concerning”, not least because it could result in increases in diabetes and cardiovascular conditions. Obesity is a major risk factor for both: an obese person’s risk of a heart attack is three times greater than that of a person with a healthy weight, and obesity-associated type 2 diabetes accounts for 90–95% of all diagnosed diabetes in adults.
Looking ahead: the role of weight-loss medicines and public health
Professor Sattar, who has been appointed as the UK Government’s new Obesity Mission Chair, said it will be important to see how wider use of effective weight-loss medicines affects obesity trends, particularly in the UK and US. “Recent signs of stabilisation in the USA suggest there may be room for cautious optimism,” he said. “Combining evidence‑based medicines with strong public health measures could begin to shift obesity rates in the right direction.” Dr Louis Aronne of Weill Cornell Medicine expects weight-loss treatments to “turn the tide” in the UK as they become more available through the NHS.
However, the picture is not universally optimistic. Professor Martin McKee of the London School of Hygiene and Tropical Medicine expressed alarm at the overall rise in obesity, warning that it “risks setting back so many of the advances in medicine” and highlighted unresolved issues within the food system. The researchers stress the need for repeated, high-quality nationwide studies to reliably monitor trends and assess the effectiveness of policies, particularly in countries like France where data after 2017 is limited. The wider use of effective medicines, alongside robust public health interventions, may offer a path forward, but the complexity of country-specific factors means no single solution will work everywhere.