Chuang Chuang and Lin Hui have a Chinese wedding.

Chuang Chuang weighs 150 kilos (330 pounds), while his partner Lin Hui is a lithe¹ 115 kilos (253 pounds), said Kannika Nimtragol, a veterinarian at the Chiang Mai zoo in northern Thailand.

"We think Chuang Chuang should not weigh over 140 kilogrammes. Otherwise Lin Hui will carry too much weight while mating," she told reporters.

To help Chuang Chuang slim down, zookeepers are feeding him fewer bread loaves and more bamboo branches to cut back on the amount of carbohydrate² he consumes, she added.

The diet program is under the careful supervision³ of Chinese panda experts. Six-year-old Chuang Chuang and his five-year-old partner Lin Hui arrived at the zoo in 2003 on a 10-year loan from China.

Giant pandas, notorious for their low sex drive, are among the world's most endangered animals.

Cutting out carbs is only the latest tactic⁴ used by the zoo in the hope of giving Chuang Chuang and Lin Hui a more loving feeling.

The two have been separated since December, in the hope absence will make their hearts grow fonder, Kannika said.

A plan to show them "panda porn" videos to coach them in mating techniques has been put on hold after research indicated that not all pandas learn from such videos.

Chiang Mai held an elaborate, traditional Chinese wedding for the couple in 2005 in the hope of encouraging them to procreate, and is considering bringing in a snow machine to help recreate a mountainous habitat.

But with the annual panda mating season due to begin within weeks, the zoo is preparing to try artificial insemination if the natural method does not work, Kannika said.