A major report on the growing problem of childhood obesity calls for "fundamental changes in our society" that would affect how children spend their time and how food is advertised, packaged and sold to them.
The report by the Institute of Medicine calls for schools to restrict vending machine sales and require at least 30 minutes of physical activity each day. Planners should design communities that encourage walking and other exercise, parents should restrict television and computer time to a total of two hours a day, and federal officials should monitor food advertising geared toward children, it says.
There are 9 million obese children in the United States, and the number is rising so fast that the problem is a major threat to the nation's health, the report says. The two-year study is the most comprehensive one to focus on the problem.
In the past 30 years, obesity rates have tripled for children ages 6 to 11 and more than doubled for teenagers and preschoolers, according to the institute, an arm of the National Academy of Sciences.
Obesity is defined as a body mass index - a calculation of weight and height - 20 percent above recommended levels.
Doctors say they are seeing increasing numbers of children with obesity-related ailments once confined to adults, including diabetes, high blood pressure, high cholesterol levels and sleeping disorders.
"It's not just that people are fat. The extra weight is causing real health threats to them," said Dr. Debra R. Counts, an endocrinologist at the University of Maryland Medical Center.
Experts blame the barrage of food advertisements aimed at children, often during the school day, larger food portions and many children's preference for television and computer games over physical activity.
The average child is exposed to 110 TV commercials a day, most of them for candy, cereal, soft drinks and fast food, studies have found. The food and beverage industry spends $10 billion to $12 billion a year marketing to children.
"We lead such stressed lives, food has become a way of coping," said Dr. Lawrence Cheskin, who treats obese families at the Johns Hopkins Weight Management Center.
The report says that combating the problem will require a shift in public attitudes similar to shifts in past decades that discouraged smoking and encouraged seat belt use.
"This is not something that can happen overnight," said Shiriki K. Kumanyika, a member of the 19-member institute committee that conducted the study and a health expert from the University of Pennsylvania School of Medicine.
Experts say that if nothing is done to help obese children, 80 percent of them will become overweight adults and face an increased risk of ailments such as diabetes and cardiovascular disease.
The federal Centers for Disease Control says poor diet and lack of exercise caused or contributed to 400,000 deaths in 2000, making obesity second to tobacco as a cause of premature deaths.
The nationwide cost of treating obesity and excessive weight problems is estimated at $98 billion to $129 billion annually.
Dr. Jeffrey Koplan, a former director of the CDC who was chairman of the committee, said fighting childhood obesity will require a coordinated effort by the food and advertising industries, parents, schools and government agencies.
"No single factor or sector of society bears all of the blame for the problem," he said.
The CDC has been warning about obesity in adults since the mid-1990s, but the institute report is seen as a major call for action.
"This is a big deal," said Kelly Brownell, a psychology professor and an expert on obesity at Yale. "The report is really a plea to government officials to take this problem more seriously and to support it with more than just lip service."
Experts in the food industry say they are voluntarily implementing some of the report's recommendations. Many restaurants offer nutritional information to customers, and more will offer it by the end of the year, said a spokesman for the National Restaurant Association.
Some experts say the panel's recommendations should be studied closely before they are implemented.
A recommendation that schools take annual weight and height measurements of every child and send the measurements home to alert parents to potential problems could be misinterpreted by some parents, said Sally Nazelrod, supervisor of the office of physical education for the Baltimore County schools.
"I would want to educate the parents before sending home something like that," she said. "I wouldn't want it to be a shock treatment."
A recommendation that physical education in the schools be increased could conflict with course requirements in what has become a busier school day.
Maryland schools require a half-credit of physical education - one semester out of four years in many schools - for a high school diploma. Requiring additional physical education in schools would mean taking time from other class work.
Many anti-obesity initiatives are under way in Maryland and elsewhere.