Chinese soldiers have become so much taller and fatter in recent years that they often find themselves cramped in tanks designed three decades ago, state media reported.

A survey found that People's Liberation Army troopers were on average two centimetres (0.8 inches) taller and five centimetres (two inches) fatter around the waist than 20 years ago, the military's official PLA Daily reported Tuesday.

As a result, it is harder for soldiers to squeeze into a tank designed for smaller personnel 30 years ago, it said.

Rifle stocks are also too short for some, limiting their accuracy, it added.

The findings of the survey, which began in 2009 and included more than 20,000 soldiers, suggested an upgrade to the military's equipment was necessary, the newspaper said, citing Ding Songtao, head of the poll project.

"Equipment must be in the right size for the battlefield, as clothes have to be in everyday life," Ding was quoted as saying.

Obesity rates have almost doubled in China since 1980, according to a recent report by the Overseas Development Institute (ODI), a London-based think tank.

The rise was attributed to diets changing with incomes rising, it said, and lifestyles become increasingly sedentary.