TOM Needles, a 12-year-old American boy, goes to the gym three times a week. Right now, he is practising leg lifts. After 30 lifts, sweat (汗水)runs down his face.

"It's pretty hard," Tom said, "but I think it's worth the effort (努力)."

Tom goes to the gym because he wants to lose weight. He is taking part in Stony Brook University Hospital's weight-loss programme (减肥课程) for children. He and 17 other kids are spending three months getting fit.

In the past 20 years, the number of overweight American teenagers has increased to 30 per cent, according to an American medical magazine. But child obesity is not just a problem in America; it is now a serious problem around the world. Many fat teens try different ways to lose weight. In China, teens are advised to eat a balanced diet (均衡饮食) and do exercise to keep healthy. In America, weight-loss programmes are very popular.

In Tom's programme, everybody goes to the gym several times a week. They also meet once a week for a healthy-eating lesson.

Tom started the programme 18 months ago. Now, he doesn't eat French fries (薯条) and other junk food (垃圾食品). He has lost more than 20 pounds (9kg). "I now feel good about myself. It's amazing," he said.