(Bloomberg) — About 2.1 billion people, or almost one-third of the world’s population, were obese or overweight last year, researchers estimated after examining data from 183 countries.

The estimated number of overweight or obese people almost tripled from 857 million in 1980, according to the analysis published today in The Lancet. The heaviest country was the U.S., accounting for about 13 percent of the world’s obese people, followed by China and India, which together represent 15 percent, according to the study funded by the Bill & Melinda Gates Foundation.

“Since 1980, no country has made significant progress in reducing the rates of people being overweight or obese,” Christopher Murray, the study author, said in an e-mail. “Obesity is now a major public health epidemic in both the developed and the developing world.”

Obesity can raise the risk of diabetes, osteoarthritis, heart disease and cancer, among other health-threatening conditions, according to the U.S. Centers for Disease Control and Prevention. Being overweight was estimated to have caused 3.4 million deaths worldwide, said Murray, director of the Institute for Health Metrics and Evaluation at the University of Washington in Seattle.

“Countries need to be looking at how they communicate effectively both what people eat and how much they should be eating,” Murray said. “Because what we’ve been doing up until now isn’t working. Strategies to tackle obesity need to address both physical activity, total caloric intake and the different foods we eat.”

BMI Measure

The researchers analyzed data from international surveys on obesity that included height and weight as well as national reports and medical research. They based their analysis on body mass index, a measure of weight and height.

A woman 5 feet, 4 inches tall weighing 175 pounds would have a BMI of 30. A BMI of 30 or more is considered obese, while a BMI of 25 to 29.9 is considered overweight, according to the U.S. National Institutes of Health.

Worldwide prevalence of obesity and overweight rose by 28 percent for adults and by 47 percent for children from 1980 and 2013, the researchers found. The number of men who were obese over that period time grew to 37 percent from 29 percent, while the number of women rose to 38 percent from 30 percent.

“The rise in obesity among children is especially troubling in so many low- and middle-income countries,” Marie Ng, the study’s lead author and an assistant professor of Global Health at the University of Washington, said in a statement. “We know that there are severe downstream health effects from childhood obesity, including cardiovascular disease, diabetes, and many cancers.”

50% of Obese

More than half of the world’s 671 million obese people live in the U.S., China, India, Russia, Brazil, Mexico, Egypt, Germany, Pakistan and Indonesia. During the more than three decades studied, the largest increase in obesity rates were in Egypt, Saudi Arabia, Oman, Honduras and Bahrain for women and New Zealand, Bahrain, Kuwait, Saudi Arabia and the U.S. for men.

In Kuwait, Kiribati, the Federated States of Micronesia, Libya, Qatar and Samoa more than 50 percent of the women are obese, while in Tonga, more than half of men and women are obese, the paper showed.

The one “bright spot,” Murray said, was that obesity and overweight rates aren’t rising as fast as they were in the past in high-income countries.

Obesity increased the most from 1992 to 2002, but has slowed in the past decade, particularly in developed countries, according to the analysis.