She is 24 months old, and her tiny frame is struggling to support her. Doctors say getting her to a healthy weight means that she cannot gain a single pound for the next three years. She is not an anomaly.

In the United States, an estimated 16 percent of children and adolescents ages 6 to 19 are overweight. The challenge and frustration for doctors who treat these youngsters is breaking through the apathy.

"We don't get it as a culture yet," says Dr. J. Mike Gilbert, a Salem, Ore., pediatrician. "Being obese is not painful, it doesn't cause anguish, and so we just don't get it."

The medical price these children will pay includes more heart disease and more strokes. Some will develop high blood pressure. Some will suffer the debilitating consequences of diabetes.

More immediate problems include skeletal strain, resulting in back pain and knee pain.

"Even if you don't keep statistics, it's just dramatic, and when you work in a pediatric office, it just assaults you and comes at you every day," says Dr. George Miller, medical director at Salem Hospital. "It's a combination of a sense of alarm and a sense of incredible discouragement."

Only in the past decade have doctors started to see childhood obesity as an epidemic, says Gilbert.

"We see five or six kids a day that should be 25 percent less in weight than they are," Gilbert says. "When you talk about one out of four kids being overweight, that's an epidemic. If we had that many cases of influenza, everybody would be up in arms."

The reasons are as complex as any solution to the situation, which the American Academy of Pediatrics cites as a "crisis" in the United States.

The most popular scapegoat is sugary breakfast foods, prepackaged lunch snacks loaded with sodium and fat and "super-sized" dinners that are quick and cheap.

But food is only part of the story, experts say.

Children aren't moving. Riding a bicycle or walking to school is almost unheard of. Climbing trees and jumping in puddles have given way to sedentary entertainment such as surfing the Internet or playing video games.

At Whiteaker Middle School in Keizer, Ore., physical-education teacher Kathy Arquette says she sees today's students as less active than those of the past.

"The biggest shift that I've seen is the entrance of technology, which is great for the cognitive end of our students, but it has aided in their inactivity," Arquette says. "When kids didn't have the video games and the televisions in their rooms — the quick access to entertainment — they went outside and entertained themselves."

In the absence of all other physical activity, a school P.E. class is not a cure-all.