When a woman with a fat aluminum kettle on her back enters a working-class neighborhood here, children quickly swarm around to share spoonfuls of the thick, syrupy porridge scooped from the vat.

This treat called "bubur sumsum Jawa" -- rice flour mixed with sweet coconut milk and sugar -- sells for about 10 cents a bowl, creating a local favorite cheap enough for many poor families in Indonesia's sprawling capital.

Indonesia has its share of McDonald's and KFCs, but far more ubiquitous and affordable are cheap street foods like the sweet porridge and "chiki-chiki," this country's catch phrase for packaged junk food. As families abandon the countryside for cities, the abundance of this poor-quality food has grown.

One result, say global health experts, is the paradox of underweight children with fat parents.

Benjamin Caballero, a physician, first noticed overweight mothers with thin, stunted children a few years ago in a Brazilian clinic. After looking closer, he found the problem was more widespread and prevalent in developing Asian nations undergoing economic transition with a high number of people migrating to cities.

A recent survey published in the International Journal of Obesity examined seven countries for underweight-overweight households. The two with the highest rates were in Asia: Kyrgyzstan with 13 percent and Indonesia with 11 percent, a finding based on data collected several years ago and adjusted for household size.

These countries are still relatively poor, but incomes are growing enough for parents to give children a few cents a day for preservative-filled, processed foods lacking vital nutrients children need to grow properly. Adults who eat them merely get fat.

Caballero, director of the Center for Human Nutrition at Johns Hopkins University's Bloomberg School of Public Health, wrote of the phenomenon in a recent commentary in the New England Journal of Medicine.

"A lot of the globalization of food markets have resulted in the introduction of many processed foods in these countries in transition, which has changed the eating habits of people," Caballero said in an interview.

Families that once grew their own fruits and vegetables now must buy everything in the city where cheap street food abounds. That change, along with more mothers working outside the home and cooking less, and families watching TV instead of working in fields, is what's leading to "dual-burden" households, Caballero wrote in the medical journal.

Changes in eating habits are apparent on Jakarta's busy streets and in its outlying neighborhoods as children like 7-year-old Raras, come home from school and beg their parents for change to buy "chiki-chiki" -- potato chips, candy, fried cassava, cookies.

"My kids prefer to eat that type of food every day," said Raras's mother, Nining, who like many Indonesians uses only one name. "I tried to forbid my kids from buying that kind of food, but I cannot."

Nining, who is chubby by Indonesian standards, said her average-size daughter began eating chiki-chiki when she was 2 years old and is now addicted to it.

An Indonesian nutritionist says the majority of families she sees are still underweight, although she's starting to see more fat children with fat parents among wealthier families.

"In the lower-income families, usually the mother or father are quite skinny and the children become undernourished or stunted -- not growing tall or not enough weight," said Uken Soetrisno, of the government Board of Research and Development of Nutrition and Food.

And while the majority of households may not have overweight and underweight members, Caballero said he's received letters from health experts all over the world who are seeing the phenomenon more and more.

He fears the problem will progress to a new phase as these countries gain more wealth -- producing overweight families, as is the trend in many Latin American countries.

To address the issue, Caballero recommends that governments recognize the phenomenon and devise intervention plans targeting underweight and overweight households.

Key prevention for both could include encouraging breast-feeding, improving nutrition among women of child-bearing age and educating communities about the importance of prenatal nutrition.

An Indonesian girl buys a sweet ice treat during lunch time outside her school in Jakarta, where there is an abundance of poor-quality, unhealthy food sold to children on the street at very low prices. An Indonesian schoolgirl eats crackers at lunch. More and more children eat "chiki-chiki" or packaged junk food.