A major new global study published in Nature reveals a starkly divided picture of the obesity epidemic. While rates have plateaued in much of Western Europe and other wealthy nations over the past two decades, they continue to climb sharply across low- and middle-income countries.
The research, analyzing data from 232 million people across 200 nations between 1980 and 2024, challenges the idea of a single 'global epidemic.' It shows trajectories differ substantially by country, age, and sex.
In most high-income Western countries, the rise in childhood obesity began slowing in the 1990s and largely plateaued by the mid-2000s. Denmark was among the earliest to see stabilization around 1990. France, Italy, and Portugal have even seen small but meaningful reversals in child obesity in recent years.
For adults, a similar trend followed about a decade later. Adult obesity in Western Europe generally remains below 25 percent, with France as low as 11 percent. This contrasts sharply with English-speaking high-income nations: in the UK, Canada, and the US, adult obesity rates range from 25 to 43 percent.
The situation is far more alarming in the developing world. In 2024, obesity prevalence was rising fastest-at more than half a percentage point per year-in 36 countries for girls and 35 for boys, led by Tonga, Samoa, and Peru. In Tonga and the Cook Islands, more than 65 percent of adults are now obese.
Even in countries where obesity was once rare-such as Ethiopia, Rwanda, and Bangladesh-rates are now climbing. Researchers attribute the trends to factors including access to ultra-processed foods, changes in physical activity, income levels, and health system responses.
The authors highlight sugar taxes as one of the few interventions showing measurable effects at population scale. They also note that weight-loss medications could become an important tool but caution that their high variable costs currently risk increasing inequalities.
The study warns that without stronger, targeted action, many low- and middle-income countries risk locking in high obesity levels for decades, placing long-term pressure on health systems.