Yum! Brands is hardly a household name, even though it's the world's biggest fast-food corporation, operating KFC and Pizza Hut to name just a few of its brands. The company is doing spectacularly well, and has primarily China to thank for its success.

Ever since KFC opened the country's very first fast-food restaurant on Tiananmen Square in 1987, China's appetite for the stuff remains insatiable. Yum! Brands now operates over 6,400 restaurants in China, opening 700 new branches in this year alone. There's no end to the expansion in sight, either. Just a few weeks ago, Yum! Brands' CEO David Novak let slip that the company's Chinese customers are set to double within the next five years.

Obesity: a growing problem

That might be good news for Novak, but China's love of greasy snacks is becoming a serious problem. The country where historians estimate that more than 40 million people died of starvation during the Cultural Revolution is now on course to become home to the world's most obese people.

One in three people in China now suffers from obesity, and the problem is not restricted to the older generation. A recent study revealed that one in 10 people aged between 20 and 39 are now either overweight or obese. Westerners might be surprised to learn that in a country with such tasty and varied cuisine, many opt instead for a cheeseburger when they're in a hurry. But while fast-food tends to be consumed by the working classes in Europe and the United States, because fresh food costs more, in China it's mostly the urban middle classes whose taste for junk food is resulting in expanding waistlines. Rice, vegetables, meat and fish are fast being replaced by Western-style fast-food.

Fast-food as a status symbol

This is because eating at places like KFC is considered sophisticated the same way that wearing Western brands is. From fried chicken to stuffed crust pizza and Big Macs, Chinese diets are becoming increasingly similar to Western ones.

As a result, China now has the world's highest number of diabetics. Diabetes and certain types of cancer can, after all, be a consequence of obesity. Treating diabetes cost the Chinese state billions in 2010.

The next statistics on the nation's health and fitness levels be published in 2015. The population's extra pounds are unlikely to have melted away by then, and the cost will be high. Even now, a fifth of the world's overweight people come from China. According to the experts' estimates, this is set to cost Beijing $400 billion. But David Novak of Yum! Brands has other things on his mind. As far as he's concerned, China represents a growth opportunity.

DW columnist Frank Sieren has lived in Beijing for 20 years.