When people picture the world’s heaviest nations, many still think of the United States or wealthy Gulf states. Yet the real numbers tell a very different story. According to the most comprehensive global analysis to date, a joint effort by the World Health Organization and the NCD Risk Factor Collaboration published in The Lancet, Pacific island countries account for nine out of the ten countries in the world with the highest prevalence of obesity among women and men aged 20 and above[1].
These small island nations, scattered across Polynesia and Micronesia, now carry some of the heaviest health burdens on the planet relative to their population size. The reasons are strikingly consistent from island to island: the collapse of traditional diets, heavy reliance on imported processed food, and a rapid shift away from physically demanding lifestyles. Below are the six countries currently sitting at the very top of the world’s obesity rankings.
1. American Samoa
American Samoa currently holds the unwanted title of the world’s most obese territory. Recent estimates place adult obesity prevalence at roughly 75 to 76 percent of the population, a staggering figure that dwarfs even the highest rates recorded in large, wealthy nations. American Samoa ranked first at 75.87%, an increase of 23.61 percentage points compared with 1980[2]. That trajectory shows just how dramatically diets and daily habits have changed on the islands over the past four decades.
Much of this shift traces back to the territory’s deep economic and logistical ties to the mainland United States, which shape what ends up on local shelves and dinner tables. Cheap, calorie-dense imported foods have largely displaced fish, root vegetables, and other traditional staples that once formed the backbone of the Samoan diet. Public health officials in the territory have repeatedly flagged obesity and its downstream effects, including diabetes and heart disease, as urgent priorities, though progress has been slow given how deeply the food supply chain is embedded in imported goods.
2. Tonga
Tonga ranks among the very highest in the world, with adult obesity now estimated well above 70 percent by some measures. Tonga follows at 73.81%, up 34.37 percentage points since 1980[2], making it one of the fastest-rising obesity trends recorded anywhere on Earth. That near 35-point jump in under half a century illustrates how quickly a population’s health profile can change when diet and activity patterns shift.
Tonga also stands out for a troubling gender gap. Tonga had the highest rate for women, with 81 percent considered obese[3]. Health researchers in the region have pointed to cultural attitudes around body size, combined with limited access to fresh produce on outer islands, as contributing factors. The Tongan government has hosted regional health forums specifically to address the crisis, recognizing that the economic and healthcare costs of untreated obesity-related disease are becoming unsustainable for a small island economy.
3. The Cook Islands
The Cook Islands consistently places among the top three or four heaviest nations in every recent global survey. The Cook Islands follow at 72.36%, an increase of 33.00 percentage points since 1980[2], a rise nearly as steep as Tonga’s. This self-governing territory in free association with New Zealand has seen its food system transformed by imports over the same period that its obesity rate nearly doubled.
What makes the Cook Islands’ situation particularly concerning is the impact on children. The Cook Islands has the highest childhood obesity rate in the world, with over 30 percent of children having obesity[1]. Health officials there have described the statistics as deeply troubling, since childhood obesity tends to carry forward into adulthood and compounds the long-term burden on the territory’s small healthcare system. Screening programs in schools have expanded in response, though the underlying dietary patterns remain difficult to reverse.
4. Nauru
Nauru, one of the smallest and most isolated nations on Earth, has long been near the top of global obesity rankings. Nauru sits at 71.39%, up 7.35 percentage points since 1980[2], a smaller increase than its neighbors mainly because its obesity rate was already exceptionally high decades ago. The country’s tiny size and near-total dependence on imported food leave residents with few alternatives to processed, calorie-dense staples.
Nauru’s economic history adds another layer to the story. The collapse of its once-lucrative phosphate mining industry left the island with limited agricultural land and a workforce increasingly employed in sedentary roles. Average daily intake of sugary drinks was high in Kiribati, Nauru, and Tokelau[4], according to research into dietary risk factors across the Pacific, underscoring how deeply sweetened beverages have become embedded in daily consumption habits on the island.
5. Tokelau
Tokelau, a tiny dependent territory of New Zealand made up of three coral atolls, rounds out the top five with an adult obesity rate estimated near 70 to 71 percent. Tokelau follows at 70.69%, an increase of 25.58 percentage points since 1980[2]. Given that Tokelau has one of the smallest populations of any territory in the world, even modest shifts in diet ripple quickly through the entire community’s health statistics.
Tokelau’s remoteness makes fresh food supply chains especially fragile, and imported goods dominate what residents can reliably access. Nutrition surveys have found that average daily salt intake in Tokelau reached 10.1 grams, roughly twice the amount recommended by the World Health Organization[4]. Researchers tracking dietary trends across the region also found that overweight and obesity prevalence increased over time specifically in Fiji and Tokelau[4], suggesting the trend has not yet plateaued there the way it may have in some other Pacific nations.
6. Niue
Niue, one of the world’s smallest self-governing states, completes this list with an adult obesity rate that has climbed dramatically over the past several decades. Niue reached 66.89%, up 26.20 percentage points since 1980[2], placing it firmly among the ten heaviest populations on the planet according to recent NCD-RisC estimates. Like its Pacific neighbors, Niue has seen its traditional fishing and subsistence farming lifestyle steadily give way to more sedentary routines and store-bought food.
Niue also shows up prominently in childhood health data, reinforcing a pattern seen across the region. Obesity researchers found that in Niue and the Cook Islands, more than 30 percent of children and adolescents were classified as obese[5], a finding that worries public health officials because it signals the trend is being passed to the next generation rather than slowing down. With such a small population, Niue’s government has limited resources to fund large-scale intervention programs, making international health partnerships an important part of its response.
Why the Pacific Dominates This List
The pattern across all six countries is remarkably consistent. Small, geographically isolated populations became heavily dependent on imported, processed foods after traditional agriculture and fishing declined as primary ways of life. In the Pacific, overweight, obesity and diet-related noncommunicable diseases have progressively increased in every age group over recent decades and have become a major cause of early death and disability[6]. Limited arable land, high shipping costs for fresh produce, and the sheer convenience of shelf-stable imports have combined to reshape diets across the region.
International health bodies have taken notice and are trying to respond. Funding from the European Union and New Zealand supports WHO’s work on obesity and noncommunicable diseases in the Pacific, with the organization’s Division of Pacific Technical Support providing tailored assistance to 21 Pacific Island countries and areas[6]. Still, reversing decades of dietary transformation in economies built around imported food is proving to be a slow and difficult process, one that will likely keep these six nations at the top of global obesity rankings for years to come.
A Global Health Challenge Beyond the Pacific
While Pacific island nations dominate the absolute rankings, it would be a mistake to view obesity as purely a small-island problem. Larger and wealthier nations show their own concerning trends, even if their percentages sit lower on the list. The top ten countries and territories in terms of adult obesity rates include American Samoa, Nauru, Tokelau, the Cook Islands, Niue, Tonga, Tuvalu, Samoa, French Polynesia, and the United States[7], showing that even a country as large and diverse as the US now ranks among the ten heaviest nations on Earth by this measure.
Middle Eastern nations tell a similar cautionary tale about rapid economic change outpacing public health adaptation. Some developed countries have relatively high obesity rates, such as Qatar at 40.79%, Kuwait at 38.88%, and Saudi Arabia at 38.13%[7]. These figures, while lower than the Pacific island nations, still represent a substantial share of the adult population and reflect similar underlying drivers: rapid urbanization, car-dependent infrastructure, and diets increasingly built around convenience rather than tradition.
Looking Ahead
The obesity crisis facing these six nations is not a static problem frozen in time. Global health researchers continue tracking these trends closely, and the picture keeps evolving as new data comes in each year. Looking at data from 2022, researchers found that more than one billion people worldwide are now living with obesity, and adult obesity has more than doubled since 1990[1], a trajectory that shows no clear sign of reversing on its own without sustained intervention.
For the six countries profiled here, the path forward will likely depend on a mix of local policy innovation and continued international support. Some nations elsewhere have shown that meaningful progress is possible, but small island states face unique constraints that larger countries do not, including limited land for agriculture, high costs of fresh food importation, and small populations that make economies of scale difficult to achieve. Whether these Pacific nations can bend their obesity curves downward in the coming decade remains one of the more pressing open questions in global public health.
What’s clear is that obesity is no longer a problem confined to wealthy Western nations with abundant fast food chains. It’s a truly global phenomenon shaped by trade patterns, economic history, and the slow erosion of traditional ways of life, nowhere more visible than on the small islands scattered across the Pacific Ocean.
