Generation XXL A society of obese children Children's impulses haven't changed much in recent decades. But social forces — from the disappearance of home cooking to the rise of fast food and video technology -- have converged to make them heavier. Snack and soda companies are spending hundreds of millions a year to promote empty calories, while schools cut back on physical education and outdoor play is supplanted by Nintendo(任天堂游戏机) and Internet. By the government's estimate, some 6 million American children are now fat enough to endanger their health. An additional 5 million are on the threshold, and the problem is growing more extreme even as it becomes more widespread. 'The children we see today are 30 percent heavier than the ones who were referred to in 1990,' says Dr. Naomi Neufeld, a pediatric endocrinologist(儿科内分泌学家) in Los Angeles. Obese kids suffer both physically and emotionally throughout childhood, and those who remain heavy as adolescents tend to stay that way into adulthood. The resulting illnesses — diabetes(糖尿病), heart disease, high blood pressure, several cancers — now claim an estimated half-million American lives each year, while costing us $ 100 billion in medical expenses and lost productivity. U.S. Agriculture Secretary Dan Glickman predicts that obesity will soon rival smoking as a cause of preventable death, and some health experts are calling for national action to combat it. Meanwhile, the challenge for children and their parents is to swim against the current. Until recently, childhood obesity was so rare that no one tracked it closely. Body-mass index (BMI), the height-to-weight ratio used to measure adult weight, seemed irrelevant to people whose bodies are still growing. But that mind-set is changing. In a gesture aimed at parents and pediatricians(儿科医师), federal health officials recently published new growth charts that extend the BMI system to children. Unlike the adult charts, which classify anyone with a BMI of 25 or higher as 'overweight' and anyone with a BMI of 30 or more as 'obese,' the childhood charts use population norms from the 1960s to determine healthy weight ranges for kids 2 to 20. According to the new charts, a typical 7-year-old girl stands 4 feet 1 inch tall and weighs 50 pounds, giving her a BMI of 15. By the age of 17, she stands 5 feet 4 and weighs 125 pounds, for a BMI of 21. To spare parents undue alarm over baby fat or the normal weight gain that precedes growth spurts(冲刺), the new charts use a broad definition of healthy weight. The heavy sufferings Even by these lenient(宽松的)standards, the proportion of kids who are overweight jumped from 5 percent in 1964 to nearly 13 percent in 1994, the most recent year on record If the trend has continued — and many experts believe it has accelerated — one child in three is now either overweight or at risk of becoming so. No race or class has been spared, and many youngsters are already suffering health consequences. Dr. Nancy Krebs, a pediatrician at the University of Colorado, notes that overweight children are now showing up with such problems as fatty liver, a precursor(先兆)to cirrhosis (硬化), and obstructive sleep apnea(呼吸暂停), a condition in which the excess flesh around the throat blocks the airway, causing loud snoring, fitful sleep and a chronic lack of oxygen that can damage the heart and lungs. Even Type 2 diabetes — known traditionally as 'adult-onset' diabetes turn up in overweight kids. 'Ten years ago 1 would have told you that Type 2 diabetes doesn't occur until after 40,' says Dr. Robin Goland of New York's Columbia-Presbyterian Hospital, 'Now 30 percent of our pediatric patients are Type 2.' Unlike Type 1 disease, in which the pancreas(胰腺) fails to produce the insulin(胰岛素) needed to transport sugar from the bloodstream into cells, Type 2 diabetes occurs when a person's cells grow resistant to insulin, causing sugar