The study, published in the latest issue of the European Journal of Preventive Cardiology, found children and adolescents in the countryside of Shandong province to be much fatter in 2014 than they were in 1985.
It was based on a survey tracking nearly 28,000 students from rural schools in Shandong, a predominantly agricultural area, over 29 years. The students were aged from seven to 18 when they were surveyed.
Some 17.2 per cent of the boys surveyed in 2014 were obese, while the rate was only 0.03 per cent in 1985, according to the thesis, reports Xinhua.
The obesity rate among girls was 9.11 per cent in 2014, while in 1985 the percentage was 0.12 per cent.
Meanwhile, the proportions of overweight boys and girls climbed to 16.35 per cent and 13.91 per cent respectively in 2014.
In 1985, the proportions were 0.74 per cent and 1.45 per cent, said Zhang Yingxiu, one of the co-authors of the thesis.
He said the increase was even more apparent among children aged from seven to 12.
The study used a cut-off of Body Mass Index (BMI) -- the ratio of weight-to-height squared -- to define overweight and obesity.