Weight constantly weighs on Olympic judo champion Yang Xiuli's mind.

"On the morning before every match, you get up on the scales," said Yang, women's judo gold medalist at the Beijing Games. 

"If you are so much as 0.1 kg, or 0.001 kg overweight, you'll be disqualified."

But she does not want to tip the scales much lower, either.

"I'll be at a disadvantage against opponents."

Yang keeps a close eye on the scales and watches her calorie intake assiduously. An extra bite or nibble could prove costly.

Yang is not alone. All the athletes staying at the national team's base, the Olympic Sports Center Hotel near the Asian Games Village in Beijing, are in the same dietary boat.

The center is hosting 672 athletes, coaches and staff members ahead of their departure for London and is the biggest among six in Beijing, according to Yan Ketong, general manager of the hotel.

The athletes eat at Wei Yuan Ting (Source of Flavor Hall), on the first floor of the hotel. The restaurant helps athletes monitor weight, energy levels and, of course, their nutrition.

The restaurant provides a buffet, instead of a set menu, and all the major food categories are served. Athletes lack for nothing regarding choice and can select from 110 different types of food.

A buffet is a practical arrangement because athletes require a high intake of calories and it provides variety, according to Yan.

Hygiene and food safety are obvious priorities.

"Meat comes from designated sources approved by the General Administration of Sport," Yan said. "Every batch must pass quality tests by a designated institution."

Athletes have been told not to dine out, have food delivered, or buy snacks outside. A notice board at the entrance of the dinning room asks athletes not to bring in food.

The restaurant keeps samples of all food served for 48 hours. Meat samples are kept even longer just in case there are any problems.

Dishes are designed based on advice from the nutrition center at the Institute of Sports Medicine.

Members of the nutrition center regularly visit the athletes and give advice on the best food for their particular discipline.

Executive chef Li Li says the most difficult part of his work is that he has to think up new dishes all the time. For example, fish and beef are served at both lunch and dinner. But they must be prepared differently.

"Dinner must be different from lunch. Tomorrow must be different from today. Next week must be different from this week," says Li. "We change the menu every month.