The obesity rate in students of Shanghai primary school last year was 15.2 per cent, up from 13.5 per cent in the previous year, the statistics released by the Shanghai Statistics Bureau and Women and Children's Welfare Committee revealed.

About four per cent of children under six were found to be suffering from obesity while 11.1 per cent of middle school students were overweight, said China Daily.

Excessive intake of calories and fat coupled with lack of exercise is the main cause of obesity in most cases, according to the report. The number of obese children in Shanghai, the most developed city in the country, has been among the highest in China for years.

About 8.1 per cent children were found to be obese in China's big cities, according to the first national survey on nutrition and health conducted in 2002.

The report also found that 29.9 per cent of primary school students suffer from bad eyesight.

What is more disturbing is the trend that poor eyesight increased considerably with school age. The figures for junior school and high school students are 61.2 and 80.6 per cent respectively.