The world is fat and only getting fatter. That is the grim prognosis given by a global network of researchers. Their comprehensive review of four decades of data paints an even more alarming picture of the obesity epidemic than originally thought.

An estimated 18 percent of men and 21 percent of women worldwide will be obese by 2025, according to the research. The United States will easily surpass those estimates with 45 percent of men and 43 percent of women becoming obese if the projections hold. Currently, 66 percent of all adults in the U.S. are considered overweight or obese.

However, in a list of the fattest countries in the world the U.S. is well outside the top 10. The most obese country in the world is the Polynesian kingdom of Tonga followed closely by Samoa.

The global numbers represent a sharp rise from 2014. That year, 11 percent of men and 15 percent of women met the obesity criteria. Perhaps most alarming, more than 6 percent of men and 9 percent of women are expected to become severely obese within the next decade.

A person is considered obese when their body mass index reaches 30 or higher. A BMI of 35 or higher is considered severely obese while 40 or higher constitutes morbid obesity.

Global Obesity Boom

Since 1975, global obesity rates among men have more than tripled from 3.2 percent to 10.8 percent. High-income English-speaking countries, including the U.S., have shown the steepest increases. Among women, the number more than doubled from 6.4 percent to 14.9 percent with the largest increases occurring in central Latin America.

The study, conducted by the World Health Organization’s NCD Risk Factor Collaboration, examines data compiled from 1975 until 2014. It includes the results of nearly 1,700 studies with more than 19 million participants representing 186 countries. The findings are published in the April edition of The Lancet.

In 2013, the United Nations unveiled plans to reverse the global obesity epidemic by 2025. However, researchers have now concluded the chances of meeting that goal are now “virtually zero.”