The incidence of diabetes linked to obesity has jumped significantly in U.S. children in the past few decades, according to new findings presented last week at a U.S. Department of Agriculture meeting on the causes and prevention of obesity in kids.

Obesity in children has emerged as a major health problem, particularly among African American girls, and Hispanic American and Native American children. One of the more worrisome trends is the sharp rise in the type of diabetes normally found only in adults.

"Childhood obesity is at epidemic levels in the United States," said U.S. Surgeon General David Satcher. "We have been remiss in shedding light on this problem, which leads to so many other health problems, particularly when we consider the threats this disease imposes on our children. Today, we see a nation of young people seriously at risk of starting out obese and dooming themselves to the difficult task of overcoming a tough illness."

The percentage of overweight children, aged 6 to 17 years, has doubled in the United States since 1968. The most recent National Health and Nutrition Examination Survey conducted by the National Center for Health Statistics from 1988 to 1994 found that one in five children in the United States was overweight.

Studies show that 70 percent of overweight kids aged 10 to 13 years will be overweight and obese as adults, Goran said. There is also psychological and emotional fallout from being overweight in childhood, as youngsters struggle with self-esteem and often become the brunt of teasing from peers.

Findings released at last week's meeting add to this troubling picture of the effects of obesity in childhood. In particular, researchers cited findings from a study of 1,000 schoolchildren in Cincinnati that showed an increasing incidence of type II, or adult onset, diabetes, the form of the disease that is closely linked to weight. In 1982, about 4 percent of children in the study had type II diabetes. By 1994, the rate had risen to 16 percent. Most children developed it between the ages of 10 and 14, researchers said, and the onset of the disease was directly linked to obesity. Other studies have found similar trends in other cities.

"It's a very dramatic problem," Michael Goran, an obesity researcher at the University of Alabama at Birmingham, told the meeting last week. "And it's not just occurring in Cincinnati, it's occurring nationally."

Obesity also puts overweight children at risk of other diseases. The Bogalusa (La.) Heart Study, an ongoing project funded by the National Heart, Lung and Blood Institute, found, for example, that overweight children tend to have readings in the highest levels of the normal ranges for their blood sugar, blood pressure and blood fats. Each of these factors places them at increased risk of health problems.

Why excess weight sets in motion a cascade of adverse health effects is not completely understood. But the latest evidence points to visceral fat, the type that hides deep within the recesses of the body, close to organs.

Visceral fat is more metabolically active, meaning that its cells churn out more byproducts, than other types of fat cells, researchers said. Included among these substances are free fatty acids that are dumped directly from the visceral fat into vessels leading to the liver. "The point is," Goran explained, "that when visceral fat releases its breakdown products, it has harmful effects on the surrounding organs."

What researchers still don't understand, however, is the relationship between visceral fat and total body fat. CT scans of the body show that not all heavy children have the same amount of visceral fat.

"What we are seeing is that obese children definitely have more visceral fat," Goran said. "But as with adults, you don't have to be obese to have a lot of visceral fat."

Nor can anyone explain why obesity has emerged as such a significant health problem worldwide during this century. During the past 15 years, the percentage of fat in the American diet has dropped from at least 40 percent to about 30 percent of total calories. There's been a proliferation of fat-free and low-fat foods.

"Despite that, the prevalence of obesity in adults and kids has increased substantially," said William H. Dietz, director of the Centers for Disease Control and Prevention's Division of Nutrition and Physical Activity.

Cultural changes in food preparation and family meals likely play a role in the problem, he said. In 1934, all food was prepared from scratch and was largely consumed based on seasonal harvests. The advent of frozen food in 1954 opened up a wider array of food choices, and the introduction of the microwave oven in 1974 meant that children could take a far more active role in choosing and preparing foods without parental guidance, Dietz said.

Adding to the problem is the recent trend of eating food that has been prepared outside the home. National food surveys show that about 30 percent of family meals nationwide are fixed outside the home, regardless of family income. Such meals often are higher in calories and fat and contain larger portions than those prepared at home, Dietz said. (See related story on Page 20.)

Lack of physical activity contributes to the problem. Fewer than half of U.S. schoolchildren participate in daily physical education. Television, video games and computers also add to the problems of sedentary living. Studies by Dietz showed that childhood obesity is related to the amount of time spent watching television.

"But television viewing is not a single behavior," Dietz said. "It represents a marker for inactivity and altered patterns of food consumption. The more television a child watches, the more likely they are to consume foods advertised on television and the more likely it is that those foods are high in calories."

There are signs, however, that some of these trends can be reversed. At Johns Hopkins Bayview Medical Center in Baltimore, Kerry Stewart, head of cardiac rehabilitation, has developed a prevention program targeted at children. "We find that we can increase the knowledge of children and improve their eating habits so that they report consuming lower percentages of fat, salt and sugars in their diet," Stewart said.

At Stanford University, Thomas Robinson and his colleagues have studied the effect of reducing children's use of television, videotapes and computer games. Using body mass index--a measurement that takes into account height and weight--the team found that they could cut BMI by half a unit in children who watched between a quarter to a third less television and videotapes and played fewer computer games.

An effective but simple change may be removing television sets from children's bedrooms. The Stanford team found that half of elementary schoolchildren they studied had a television set in their bedrooms.

"If there's any one thing that parents could do, it's that," Robinson said. "There's no reason for a child to have a television in the bedroom."

(I hope there weren't too many millions spent studying the effect of having a television in a child's room. Some things are just OBVIOUS.........ed)