A national report indicates that Chinese kids have grown rapidly in both height and weight over the past 40 years, with experts calling for more exercise and sleep to ensure children develop healthily.

The National Health and Family Planning Commission released the Fifth National Children's Growth Report on Wednesday, which took 161,000 children nationwide under the age of 7 as the sample.

It found that both boys and girls had increased in both height and weight from 1975 to 2015. And the increases were most notable in the group aged between 6 and 7.

The average height of boys in this age range increased from 112.2 centimeters in 1975 to 121.5 cm in 2015, while the average height of girls rose from 111.4 cm to 120 cm during the same period.

The average weight of boys aged from 6 to 7 years had increased by 4.82 kilograms during the four decades, while the average weight of girls in the same age group had increased by 4.05 kg.

"It shows that the Chinese people now enjoy better living conditions and nutrition than 40 years ago," said Zhu Zonghan, vice-chairman of the China Maternal and Child Healthcare Association.

"But we should be alert to the problem of obesity among children," he said.

The obesity rate among children under 7 years old had risen from 3 percent in 2001 to 9 percent last year, according to Zhu.

Children who are overweight or obese have a higher risk of diabetes, according to Zhang Ting, deputy director of the Capital Institute of Pediatrics in Beijing.

He attributed the two problems to the country's economic development and changes in lifestyle, with youngsters eating more but doing less physical exercise .

The commission released a new dietary guideline in May, emphasizing the importance of a balanced diet.

It takes into account the main nutritional problems and eating habits of Chinese, and lays out a nutritious and healthy diet that will help people maintain health and prevent disease.

"Our next task will focus on improving children's nutrition in rural areas. And the data in our latest report on children's health will be used a reference," said Mao Qun'an, spokesman of the commission.