Children in Hong Kong are being warned of a growing serious health risk - obesity.

In a single generation, Hong Kong children have moved from healthy traditional diets to living on fast food and high fat snacks.

During break time, secondary school students crowd round food stalls, buying fried chicken wings, crisps and other fatty snacks.

Children are taller and fatter than they used to be. But their cholesterol levels are amongst the highest in the world and obesity is being seen as the top health risk.

Plump children

Dr Henrietta Ip: "Parents like plump children"

Dr Henrietta Ip, a paediatrician who chairs the Hong Kong Child Health Foundation, says parents, she says, like their children to be plump.

"They don't see it as a problem. That is more worrying," she said. "Traditionally, little fat babies are loved and thought to be healthy. Parents are very proud that their children are a bit podgy.

"Because they are fat when they are little, they grow up into little fat kindergarten children, become fat primary schoolchildren and this goes on. In fact, the parents may be quite fat."

Busy fast food restaurants are part of the problem. With both parents often working full-time, the traditional Chinese diet with several shared dishes is being swapped for convenience foods.

Home alone

Paulina Ng: "Fatty western food seen as fashionable"

Hospital dietician Paulina Ng sees a growing case load of fat children. She says many children eat alone in the evening, choosing fatty western food which is fashionable and high status.

"It's a compensation, you know, because the parents go to work in the daytime. They don't have any communication with their children," she said.

"So they usually buy packets of junk snacks for their kids, just for compensation, to show their love to them, you know."

As well as eating junk snacks, many children do not get regular exercise.Hong Kong is one of the most overcrowded cities in the world and playing fields are in short supply.

Dr Ip: " Children adopt lifestyle of parents"

Dr Ip says most children spend their free time indoors.

"They adopt the lifestyle of their parents. They sit in front of the television, in front of the computer, they have transport to go from home to school and school back home," she says.

"All the high rises have fantastic fast lifts so they don't have to walk upstairs or downstairs. It's unheard of to walk."

Medals for fitness

Carmen Li: "Children still fat"

The authorities have launched a special awards scheme to try to persuade children to get fit. Children train at school for regular tests in running, sit ups and other exercises, winning medals if they pass.

Teacher Carmen Li has made the scheme compulsory for all her pupils. But even so, about a third of the children are still fat.

"They cannot control themselves to eat. Hong Kong student have an abundance of snacks to buy everywhere," she says.

"They will eat every time. Maybe some of them will eat during their lessons."

One of Ms Li's star pupils is Geoffrey. He eats sensibly, loves sport and already has a silver medal in the awards scheme.

But many of his friends would rather sit down than join him on the sports field.

"Some like playing basketball or football but I know some of them don't like to play. They just like to play computer games at home or reading books," says Geoffrey.

No motivation

While fit children like Geoffrey win the awards, the fatter children are less enthusiastic about running round the playground and doing sit ups. Their teacher Ms Li admits it is hard to motivate them.

"It's very difficult for them, for the fat boys or fat girls to do exercise. They're very heavy and they need more effort and more confidence. They think that it's very difficult and very uncomfortable to make many sweat," said Ms Li.

But getting fit could prove an issue of life and death. The western diet is bringing western-style disease.

Heart attacks are now affecting those in their thirties and forties, something almost unheard of in the past.

For the fat children now refusing to play outside, heart disease could come even earlier.