There are many theories about what causes obesity. There's certainly no one cause. And the causes may vary from one person to another. Many scientists believe that obesity often has its roots in childhood. The theory is that an individual's metabolism is set at a young age. That determines how efficiently the body stores food and expends energy -- and how easily we gain weight.

So it's especially alarming that children's weight has been increasing so fast. Here in the United States, the number of obese children has tripled since 1980. In part III of our series on global obesity, The World's Patrick Cox takes us to a country that has succeeded in reversing the trend toward greater childhood obesity but that success has come at a cost.
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Cox: The city-state of Singapore has a well-earned reputation for conformity and discipline. When the government directs its citizens to act, they generally snap to it.

"Get out of your seat onto your feet. Get your body moving like mine. It's Singapore, Singapore work out time."

Cox: This public service announcement from the early 1990s called on Singaporeans to join a mass work-out. The country's prime minister led the event. 26,000 people took part, enough to break the world record for a gymnastic display. It was the start of a big government push to get citizens, especially children, to lose weight.

Since then, Singapore has achieved remarkable success in its fight against childhood obesity. The proportion of school-age children classified by the government as obese has fallen from 14% to 9% in the past 15 years. During that same period, just about everywhere else in Asia has seen childhood obesity rise. Public health experts from around the world are studying Singapore's approach as a possible model to be replicated.

It's an approach that centers on schools

Cox: It's lunch period at Rulang Elementary School in western Singapore. In the schoolyard, some 30 uniformed 6th-graders are about to begin a 20-minute aerobic workout. Afterwards, they'll scarf down a meal in the ten minutes that remain of their lunch break.

"Ready and go!"

Cox: This is a school fitness club. It meets every other day for strenuous exercise. Participation is mandatory for overweight students.

Cox: Tell me, how long have you been doing the program for?
Student: one year, two years.
Cox: so have you guys lost weight?
Students: Yes.

Cox: These 6th-graders seem eager to please an outsider asking them questions. They say the fitness club is fun. They enjoy the exercises, most of them variations of tag. But after their teacher leaves the room, they talk about the club's downside: other kids call them names.

Students: "Pig -- Some people call us pig. and if you see my name – my name is zul – so if you translate it directly into Chinese it's pig. so most of the people insult me. "

Cox: Of course, such taunting of overweight kids is hardly unique to Singapore. But while schools in other countries try to stop this kind of behavior by telling children that everyone is equal and worthy of respect, Singapore's program has exacerbated the stigma of being overweight. By dividing the children into two groups – the fit and the fat – the schools impose a kind of segregation. And this segregation can extend outside the clubs, into the cafeteria. Ho Soh Heng is the Rulang school's deputy principal.

Ho Soh Heng: "I know of schools—I'm not going to mention names – they do have in their canteen specific tables just for children who need to eat differently, and during recess these children sit there, and they are monitored./ Other children will look at them and say oh this is a special group, you know?"

Cox: In the early days of the program heavyset children were even given calorie coupons to spend at school cafeterias. The larger the child, the fewer the coupons he could spend.

Jaslyn Ng

Singapore named its weight-loss clubs Trim and Fit Clubs, known universally by their acronym, TAF. Intentionally or not, TAF spells "fat" backwards, and so it's hardly a surprise that they're often called Fat Clubs by non-members. Jaslyn Ng was in a TAF club for four years. She's 23 now, and cringes when recalling those days.

Ng: "When you go to TAF club, people laugh at you. Guys will say "You are so fat" and then "You are a girl, you know, why are you eating so much?" It's quite upset."

Cox: Ng's psychologist, David Kan, counsels several past members of Trim and Fit clubs. He says some of these children are deeply scarred by the experience.

David Kan

Kan: "They do feel the stigma that I'm being short-listed for this program means I'm labelled a person that is obese and as a result I may be a potential outcast in the school. And to them, if I am fat perhaps I'm a failure, I am a loser. "

Cox: And the resulting shame may cause real harm. A few years ago, a prominent academic study blamed the Trim and Fit Program for an increase in eating disorders. Officials denied the connection, but psychologist David Kan wasn't surprised. He's seen eating disorders and depression among his own clientele. He says school officials didn't listen when he told them that eating and body size are caught up with self esteem. He says adolescents in particular lose confidence when they're singled out and told to diet.

Kan: "Every spoon of soup you scoop, or every speck of noodles you pick with your chopsticks, it effects your confidence as you grow. "

Cox: Education officials insist that no-one set out to stigmatize overweight children. It's just turned out to be a by-product of the program – a by-product nonetheless tolerated by officials for 15 years. Warren Lee is a paediatrician and chairman of the Diabetic Society of Singapore. He says the Trim and Fit clubs are really "cruel-to-be-kind."

Lee: "Like it or not if a young person were to go through life with a weight problem, they would face disadvantages on the job market. And if you don't address it at the formative stage when they can still do something about their weight, then we're actually doing them a disservice."

Cox: Criticism of the Trim and Fit program has gradually mounted in Singapore. And this year the government bowed to the pressure. Starting this fall, officials are trying to reduce the program's stigmatizing aspects. The calorie coupons have disappeared. The fitness clubs are now open to all students irrespective of body size. However, the overweight kids are still required to participate, and there's little evidence that other kids are choosing to join the clubs.

Yet there's an uncomfortable fact about Singapore's program that health experts are reluctant to acknowledge. It's possible that the program was successful not in spite of the stigma it induced, but because of it. Some former club members certainly believe that. They say that the act of segregating them and labelling them as different motivated them to change. What's more, school programs in other countries that don't segregate overweight kids have largely failed to reduce childhood obesity.

Barry Popkin runs a global obesity center at the University of North Carolina. He calls the obesity epidemic the world's number one public health challenge. So, he admires what Singapore has done, even if some consider it heavy-handed and insensitive.

Popkin: "We don't want to make people who are heavy feel like they are lesser human beings, and we need to show understanding of them. At the same time, this obesity problem is going to destroy our civilization as we know it. If we're at a point where half the people are diabetic and have other heart conditions you're really facing major societal problems of how to survive. "

Cox: Popkin says too much stigma can cause real harm. But he believes just as strongly that too little may not be good either.
The question now: can Singapore maintain its program's success without making the overweight kids feel like failures?