Lu Weishan, who at 5-foot-5 inches and 538 pounds is believed to be the heaviest woman in China, has undergone a drastic weight-loss operation.

After trying and failing to lose the necessary pounds to put her at a healthy weight, the  31 year old underwent gastric bypass surgery in Changchun, capital of China's Jilin Province.

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Lu says she's addicted to food, and ate two or three times what other children ate when she was little, according to local media reports. She was 33 pounds heavier the other children when she entered primary school. By the time she was in high school, her weight had reached 210 pounds, and when she reached college, she tipped the scales at 328 pounds.

Because of her excessive weight, Lu says she shut herself in her home for six years, only finally coming out last month when she heard of the obesity treatment in Changchun.

About one fifth of the one billion overweight or obese people in the world are Chinese, according to a report by Yangfeng Wu, a professorial fellow at  the Peking University School of Public Health.

"China was once considered to have one of the leanest populations, but it is fast catching up with the West in terms of the prevalence of overweight and obesity," said Wu in his report. "Disturbingly, this transition has occurred in a remarkably short time."

And according to a report from the University of Washington's Institute for Health Metrics and Evaluation, China has the second-largest number of obese people in the world behind only the U.S. Worldwide, there are 2.1 billion people who are overweight, 671 million of which are classified as obese.

A person is classified as overweight if he or she has a body mass index of between 25 and 30. Body mass index factors in weight in relation to height. A BMI of 30 or above is considered obese.

Pauline Potter of California is considered the heaviest woman in the world with a weight of 643 pounds, as recorded by the Guinness World Records 2012 record book.

TagsChina's Heaviest Woman Undergoes Drastic Operation, Lu Weishan, gastric bypass surgery, obese, obesity