Obesity in children raises the risk they will develop diseases, including Type 2 diabetes, sleep apnea and depression.'We are seeing a marked increase in what we used to call adult diseases [in children],' said said Aaron Carrel, an associate professor of pediatrics.

"Obviously there has to be some upper limit," said lead author Cynthia Ogden, a researcher with the US Centers for Disease Control and Prevention. "I just don't know where it's going to be."

The number of obese and overweight men also increased, although an encouraging sign was that obesity in women remained constant at about one-third of the population aged 20 and over.

Calorie-Restriction Benefits

At the other end of the spectrum, a separate group of researchers found that depriving people of about 25 percent of their normal calories, while still eating nutritionally balanced diets, led to physiological changes associated with increased longevity.

The six-month month study involving 48 people -- the first in non-obese humans -- showed that calorie restriction led to improvements in insulin levels, a beneficial decrease of about one degree in body temperature and less DNA damage to cells.

Numerous animal studies have showed that calorie restriction, which slows metabolism, can extend life span by as much as one-third.

"The next phase is to look at more people for a longer time," said co-author Steven Smith, an associate professor of endocrinology at the Pennington Biomedical Research Center in Baton Rouge, La.

Both studies were published Wednesday in the Journal of the American Medical Association.

'Things Are Worsening'

The national obesity study is considered one of the most credible estimates of the problem because it included actual weight and height measurements of 3,958 adolescents age 2 to 19 and 4,431 adults age 20 and over. Other surveys simply ask people for those measurements, which tend to be inaccurate.

The study found that in 2003-2004, 17.1 percent of 2- to 19-year-olds were obese, up from 13.9 percent in 1999-2000 and 15.4 percent in 2001-02.

The biggest increase was found in 6- to 11-year-olds, up from 15.1 percent in 1999-2000 to 18.8 percent in 2003-04.

"It's during childhood that our patterns often are set," Ogden said. "Overweight adolescents often become obese adults."

The number of overweight kids also increased, up from 30 percent in 2001-02 to 33.6 percent in 2003-04.

The finding shows that childhood obesity is not leveling off and that much more needs to be done, said Aaron Carrel, an associate professor of pediatrics at the University of Wisconsin-Madison.

"It's a pretty loud message that things are worsening," said Carrel, who works with obese kids.

Communities, schools and health insurance companies need to do more to address the problem, he said.

He said obesity in children raises the risk they will develop diseases, including Type 2 diabetes, sleep apnea and depression.

"We are seeing a marked increase in what we used to call adult diseases [in children]," Carrel said.

The increase in juvenile obesity is caused by a variety of factors, including television and video games, high-calorie foods such as soda that have little or no nutrition, and a family environment where overeating and a lack of exercise are the norm, said Safak Guven, an assistant professor of medicine at the Medical College of Wisconsin.

"It (obesity) is a chronic disease that needs to be treated as such," said Guven, who also serves as clinical director of the obesity and metabolic syndrome clinic at Froedtert Memorial Lutheran Hospital.

Overweight, Obesity, Extreme Obesity

Obesity in adults has been a mounting problem for nearly a quarter century. The adult obesity rate doubled between 1980 and 2002.

In the latest study, overall adult obesity increased from 30.6 percent in 2001-02 to 32.2 percent in 2003-04, but nearly all the increase was in men whose rate increased from 27.8 percent to 31.1 percent during that period.

For women, the obesity rate went from 33.3 percent to 33.2 percent.

"Basically, men are catching up to women," said lead author Ogden.

Researchers had differing opinions on whether the next survey will find a leveling off among adults.

The authors of Wednesday's study said that the obesity rate in women appears to be leveling off. Obesity in those age 60 and older declined, they also found.

However, Guven said he believes that if more isn't done to address the issue, the obesity rate in adults could reach 50 percent in the next decade.

The study also found an increase in the number of overweight Americans. In 2003-04, 66.3 percent of adults were overweight, compared with 64.5 percent in 1999-2000 and 65.7 percent in 2001-02.

Again, the increase was fueled by men. In 2003-04, 70.8 percent of men were overweight, compared with 70 percent in 2001-02 and 67.2 percent in 1999-2000.

A total of 4.8 percent of adults were extremely obese, down from 5.1 percent in 2001-02. Extreme obesity was much more common in women (6.9 percent) than men (2.8 percent).

Overweight is defined as having a body mass index of 25 or more; obese is a BMI or 30 or more; extreme obesity of a BMI of 40 or more. BMI is a formula that relates weight to height.