Obesity has quietly become one of the defining public health challenges of the 21st century. The worldwide prevalence of obesity has more than tripled between 1975 and 2022. That trajectory is not slowing down. In 2024, the NCD Risk Factor Collaboration estimated that more than one billion people in the world are now living with obesity, including nearly 880 million adults and 159 million children and adolescents aged 5 to 19 years.
The countries at the very top of the global rankings tell a striking story. Most of them are small Pacific island nations, places that barely register on a world map but that carry an outsized burden of chronic disease. Eight of the top ten countries with the highest obesity rates are located in the Pacific Islands, a region grappling with the effects of globalization on diet. The remaining entries come from the Middle East and North America. Here is a closer look at the nine countries where the obesity crisis is most severe.
1. Nauru: The World’s Most Obese Nation
The World Health Organization has estimated that 94.5% of Nauruans are overweight or obese, and Nauruans aged 27 to 40 years old have an average weight of more than 100 kilograms, with an obesity rate of roughly 71.7%. That is a staggering figure for any population, but for an island of just about 10,000 people, the health implications are catastrophic.
With much of the landscape destroyed from phosphate mining, Nauru was forced to import food resources from Western countries, leading to a sharp increase in consumption of processed food. With healthy food depleted from the island, obesity rates continued to climb. Nauru also holds the highest rate of adult diabetes worldwide, with the International Diabetes Federation identifying roughly a third of Nauruans as diabetic, with rates as high as 45% among individuals aged 55 to 64.
2. American Samoa: A Territory in Crisis
American Samoa leads the global rankings with an unprecedented obesity rate of around 70 percent among its adult population, making it the country facing the world’s most severe obesity crisis. This U.S. territory in the South Pacific has seen generations grow up in an environment where calorie-dense imported food is the norm and fresh produce is scarce and expensive.
American Samoa holds the highest or second-highest obesity rate globally, followed closely by Nauru. Pacific Island nations dominate the top rankings, largely due to genetic predisposition, dietary westernization, and limited access to fresh produce. In 2022, data from the WHO found the prevalence of obesity in American Samoa at approximately 75 percent of adults, among the highest ever recorded for any territory.
3. Cook Islands: Where Half the Population Faces the Same Struggle
With roughly 66 percent of adults classified as obese, the Cook Islands confronts extraordinary health challenges that require urgent intervention and sustainable policy changes. This small South Pacific nation of around 15,000 people has become a case study in how globalization can dismantle traditional food cultures in a single generation.
Between 1980 and 2008, the Cook Islands experienced one of the fastest rates of increasing BMI in the world, at rates over four times higher than the mean global BMI increase. More than half of the Cook Islands population have a body mass index of 30 or above, and Cook Islanders are dying prematurely due to a poor diet.
4. Palau: Modernization at a Heavy Price
Obesity is a significant issue in Palau, with more than half of the population experiencing an obesity epidemic, largely due to the country’s limited availability of wholesome food options. The fact that Palau is made up of roughly 500 islands makes distributing healthy food to all areas difficult, leaving many of its 20,000 citizens with limited access to nutritious options.
Instead of using energy to hunt, fish, and gather, Palauans have traded tradition for convenience. Conserving energy and poor nourishment result in less physical activity on the remote Pacific island. The result is a population increasingly burdened by type 2 diabetes, cardiovascular disease, and related conditions that strain a healthcare system with limited resources.
5. Tonga: A Kingdom With a Growing Health Emergency
Tonga is a monarchical nation in the Polynesian archipelago of the South Pacific. Tongans are facing an obesity epidemic primarily driven by changing dietary habits, as traditional, healthy foods are replaced with imported products high in salt, fat, and sugar. This shift in nutritional habits has led to a significant increase in overweight and obese individuals.
Life expectancy in Tonga sits at 71 years, and up to 40% of the population is said to have type 2 diabetes. Among females, the prevalence of overweight and obesity has reached 88% and above in Tonga, Kuwait, Cook Islands, Nauru, and Samoa combined. The scale of the metabolic disease burden in Tonga is one of the most pressing in the entire Pacific region.
6. Niue: The Small Island With a Massive Burden
Niue is a small island nation roughly 1,500 miles from New Zealand. With just over 2,000 people, Niue has roughly half of its population considered obese or overweight, a weight problem largely driven by the consumption of processed food. For a territory this size, even modest absolute numbers translate into a near-total population health crisis.
Processed food is often cheaper and more readily available than healthier options, a reality that shapes everyday eating habits across the island. Nutrient transition is the primary cause of the obesity epidemic in the Pacific Islands, with a high amount of imported foods high in salt and fat content. Much of the local diet consists of processed, salty, and calorie-dense imported food such as spam or corned beef, rather than traditional fresh fish, fruit, and vegetables.
7. Tuvalu: A Vanishing Island With a Worsening Crisis
In the Pacific island nation of Tuvalu, the transition to a diet of heavily processed, low-cost food has devastated the population’s health. Tuvalu is better known internationally for its vulnerability to rising sea levels, but the obesity crisis it faces is equally urgent. The country sits among the top ten most obese nations on earth by adult prevalence.
High rates of obesity in Pacific island populations appear within 15 months of birth, suggesting that the problem starts before children even develop independent food choices. Obesity is leading to increased levels of illness, including type 2 diabetes, heart diseases, and other associated noncommunicable diseases that are overwhelming the limited medical infrastructure these islands can realistically sustain.
8. Kuwait: The Middle East’s Heaviest Nation
Kuwait reports an obesity rate of around 45%, placing it among the highest in the Middle East and making it one of the most affected nations outside the Pacific. Middle Eastern countries like Kuwait, Qatar, and Saudi Arabia show extremely high rates, likely linked to sedentary lifestyles and high-calorie diets. The speed of Kuwait’s economic transformation over the past half century has outpaced any meaningful public health response.
Obesity is classified by the WHO as a chronic, relapsing disease arising from complex interactions between genetics, neurobiology, eating behaviors, access to healthy diet, market forces, and the broader environment. In recent decades, obesity has expanded globally as countries have experienced greater food security, socioeconomic development, and shifts in diet, physical activity, and societal and individual behavior driven by globalization and industrialized food systems. Kuwait represents a textbook example of that pattern.
9. United States: The World’s Most Obese Large Nation
The United States has an obesity rate of around 42 percent as of the most recent estimates, representing a steady increase. This makes the U.S. the most obese developed nation, with rates continuing to rise despite public health interventions. For a country with one of the world’s most advanced healthcare systems, that trajectory reflects just how deeply structural the problem has become.
The prevalence of obesity in the United States increased from 18.6 percent in 1990 to 42.0 percent in 2022, more than doubling over three decades. The United States ranks among the top 20 countries globally with an obesity rate above 42%, making it the highest among large developed economies. The World Obesity Federation’s 2025 Atlas projects that the total number of adults living with obesity will increase by more than 115% between 2010 and 2030, from 524 million to over 1.1 billion, a trajectory that places countries like the U.S. on course for even sharper economic and healthcare costs in the decades ahead.
