For men, the obesity rate more than tripled over the past four decades, rising from just over 3 percent to nearly 11 percent. Among women, the rate more than doubled, rising from more than 6 percent to nearly 15 percent.

Ezzati collaborated with more than 700 public health experts around the world to identify and collect obesity estimates for most countries from 1975 to 2014. He directs that network of experts, known as the Noncommunicable Diseases Risk-Factor Collaboration, or NCD-RisC. The estimates are based on a person’s body-mass index.

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If the global trend continues, Ezzati and his colleagues estimate, nearly 18 percent of men and 21 percent of women will be obese by 2025.

Ezzati and his colleagues define obesity as a BMI of 30 kilograms per square meter or more. Under that definition, an average American male who is about 5 feet and 9 inches tall would be considered obese at a weight of 205 pounds or more. For an average American female who is nearly 5 feet and 4 inches tall, the cutoff would be about 174 pounds.

Here’s what the four-decade spread of obesity looks like for men and women, according to images of the interactive maps that he and his collaborators created.

(Note: The maps show how the obesity rate changes within each country. In other words, the values are relative.)

Despite having less than a quarter of the population of China, the United States contributes about as much as that Asian nation to the world’s obese population. Globally, roughly 1 in 3 obese men call either China or the United States home, while those two countries are home to about 1 in 4 obese women.

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But few countries were immune to the four-decade rise in obesity. As the charts below show, nearly every region of the world saw rates increase for both sexes.

To Ezzati and his colleagues, the implications of their research are clear.