Why are children in rural China suddenly becoming obese?
Scientists are blaming a lack of exercise and good old American food.
Researchers, in fact, are predicting that China's enthusiasm for a Western-style diet of junk food and soft drinks is setting the stage for big increases in diabetes and heart disease there.
This news was revealed in the results of a 29-year study just published in the European Journal of Preventive Cardiology.
The study, "Trends in overweight and obesity among rural children and adolescents from 1985 to 2014 in Shandong, China," followed nearly 28,000 children and adolescents.
It's a trend that is being seen elsewhere in the world, too.
Chinese physicians, led by Dr. Ying-Xiu Zhang, found that less than 1 percent of children and adolescents in their country were obese in 1985 compared with 17 percent of boys and 9 percent of girls in 2014.
The authors speculated that more boys might be overweight than girls because of a societal preference for sons.
"China is a large agricultural country and our findings have huge implications for the entire nation," said Zhang in a press release. "The rises in overweight and obesity coincide with increasing incomes in rural households and we expect this trend to continue in the coming decades in Shandong province and other regions of China."
Professor Joep Perk is the cardiovascular prevention spokesperson for the European Society of Cardiology. In a press release, he called the results "extremely worrying."
"It is the worst explosion of childhood and adolescent obesity that I have ever seen," Perk said. "The study is large and well run, and cannot be ignored. China is set for an escalation of cardiovascular disease and diabetes, and the popularity of the Western lifestyle will cost lives."
A child obesity expert in the United States echoes Zhang and Perk's concerns.
Dr. Robert Lustig, a pediatric endocrinologist at the University of California, San Francisco (UCSF), is director of the UCSF Weight Assessment for Teen and Child Health program.
"The obesity epidemic in China correlates with the advent of processed food and soft drinks," Lustig said in a Healthline interview. "It's the sugar. Added sugar in foods adds 7 to 8 percent weight gain in body mass index. But sugar is only 10 percent of total weight gain. The top two sources are potato chips and french fries."
Lustig has spent two decades treating childhood obesity, and studying the effects of sugar on the central nervous system and metabolism.
He is author of the New York Times bestseller, "Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease" (Plume 2013). He is also the founder of the Institute for Responsible Nutrition.
China, India, and Pakistan have a 12 percent diabetes rate, but they are not fat, he said. Americans are the most overweight but have a diabetes rate of only 9 percent.
"When you stand on a scale you measure four different factors," Lustig said. "Bone: more is better. Muscle: more is better. Subcutaneous, or 'big-butt' fat: more is better. But abdominal or visceral fat is responsible for morbidity. More is worse."
The problem is not just in China and the United States, Lustig said. Obesity is growing globally in every country.
Sugar, which metabolizes differently and only in the liver, is causing nonalcoholic fatty liver disease in China and India, Lustig said.
"Sugar is a chronic, dose-dependent liver toxin. Once there's fat in your liver, you're sick," he noted.
The Chinese study found that the prevalence of overweight and obesity in boys increased from 0.74 percent and 0.03 percent in 1985 to 16.35 percent and 17.20 percent in 2014.
Obesity in girls increased from 1.45 percent and 0.12 percent in 1985 to 13.91 percent and 9.11 percent in 2014.
"China has experienced rapid socioeconomic and nutritional changes in the past 30 years," Zhang said. "In China today, people eat more and are less physically active than they were in the past. The traditional Chinese diet has shifted toward one that is high in fat and calories and low in fiber."
Societal preferences and resource allocation may be driving the epidemic.
Zhang and his team speculated that boys might become fatter than girls because families in rural China prefer sons, and spend more family resources on them.
The Chinese 2005 National Youth Risk Behaviour Surveillance reported that 4 percent of boys and almost 3 percent of girls frequently consumed soft drinks, while 12 percent of boys and 4 percent of girls spent more than two hours per day playing computer games.
Perk said that computer games are not the issue.
"The problem is that kids sit there with a 2-liter bottle of fizzy drink. To burn those calories they would need to walk 46 kilometers, but they don't," he said.
The study also found that overweight and obesity are rising faster in children ages 7 to 12 than in adolescents 13 to 18. The scientists concluded that particular finding could be driven by teenagers' greater concern about personal appearance, which could motivate them to get more exercise.
"Rural areas of China have been largely ignored in strategies to reduce childhood obesity," Zhang said. "This is a wake-up call for policymakers that rural China should not be neglected in obesity interventions."
Lustig said obesity is just one of the long list of illnesses that are part of the "metabolic syndrome" --which includes diabetes, hypertension, lipid abnormalities, cardiovascular disease, nonalcoholic fatty-liver disease, polycystic ovarian disease, cancer, and dementia.
Metabolic syndrome illnesses caused by sugar consume 75 percent of America's healthcare costs, he said.
"We think of sugar as bad because of calories, but sugar is not just like other calories," Lustig said. "It's especially detrimental and unrelated to calories and effect on weight gain."
Forty percent of Americans do not drink alcohol, he said.
And there was no processed food industry until 1965. It started, Lustig said, with SPAM during World War II and then TV dinners.
"Many years ago, everybody had a 5-pound bag of sugar at home. They used it for coffee and for baking. But now our food has become contaminated with sugar, poisoned. The U.S. food industry has 56 names for sugar and it uses all of them to hide the sugar in their food.
Since 2013, five scientific papers have been published -- including three by Lustig -- that demonstrate sugar's critical role in metabolic disease.
Governments and national agencies are beginning to respond to the sugar problem.
In January 2016, the USDA issued new dietary guidelines. These include encouraging Americans to consume less than 10 percent of their daily calories from added sugars.
When the G-20 nations met in November 2015, the International Diabetes Federation lobbied leaders to establish a sugar tax. The United Kingdom enacted a sugar tax in March.