(CNN) One in five Chinese children is overweight or obese, a new study has found, up from just 1 in 20 in 1995.
The research, published Tuesday, found that while China's rapid economic growth over the past two decades had been accompanied by a reduction in childhood growth stunting and thinness, the country has also seen a four-fold rise in the number of overweight and obese children.
The authors said they were concerned to see such a marked increase. "This suggests a pressing need for policy responses that may include taxation of food and beverage with added sugars and fats, subsidies to promote dietary diversity, and strategies to promote physical activity and health education," said the study's co-author, Peking University professor Jun Ma.
China's economy has boomed in recent years and is now the world's second-largest. The authors said their study was the first to evaluate the effect of economic growth on malnutrition in all its forms, and previous studies have focused solely on under nutrition.
Increasing incomes have allowed households to spend more on food, and urbanization has made it much easier for families to access better health care and education.
But, at the same time, it's much easier for Chinese kids to eat junk food, and kids are less physically active than they used to be, said Bai Li, a research fellow at the Institute of Applied Health Research at the University of Birmingham in the UK, who wasn't involved in the research.
"Children used to use their spare time to play outside; now they are inside in front of computers and the TV. There are many fast food chains in China now and many Chinese people are adopting new food like this," she said.
Childhood obesity is on the rise around the world, and the World Health Organization has called it "one of the most serious public health challenges of the 21st century."
Li said that a lagging perception of what's healthy had underpinned the increase in childhood obesity in China.
"People still think being fat is a good thing. It's particularly true for older generation. They often grew up in poverty when food was scarce," said Li, who has studied the role of grandparents in childhood obesity in China.
"Grandparents often live with the family and given that parents often both work, they play a big role in deciding what children eat."
In the study, which was published in the the Lancet Diabetes & Endocrinology, researchers used data from more than 1 million Chinese children ages 7 to 18 between 1995 and 2014.
It found that the prevalence of stunting in Chinese children and adolescent due to long-term insufficient nutrient intake and infections decreased from 8.1% to 2.4% in that time period, and thinness declined from 7.5% to 4.1%.
On average, the number of Chinese children classed as overweight or obese increased from 5.3% in 1995 to 20.5% in 2014.
Current levels of obesity among Chinese adults are among the lowest in the world, said Lindsay M. Jaacks, an assistant professor at the Department of Global Health and Population at the Harvard T.H. Chan School of Public Health, making this study particularly worrying.
"The importance of this finding cannot be underestimated, considering evidence that excess weight gained in childhood is carried into adulthood and increases the risk of type 2 diabetes, cardiovascular disease, and some cancers," she wrote in a commentary published alongside the research.
"In the absence of strong nutritional governance, China is likely to see a substantial increase in the prevalence of adult obesity as the current cohort of children and adolescents ages."