(HealthScoutNews) -- There's been much focus on disturbing increases in child obesity in the United States in recent years. But new research shows that many Americans make the hefty jump from mildly overweight to clinically obese in their early 20s or mid-30s.

Reflecting national obesity trends, blacks and Hispanics appear to put on pounds the fastest, with the research showing that black women became obese more than twice as rapidly as white women. Among men, Hispanics put on pounds the fastest -- about 2.5 times faster than white men.

The findings are based on a review of 9,179 people born between 1957 and 1964 who were enrolled in the National Longitudinal Survey of Youth. The survey offered weight data on the subjects from 1981 through 1998.

In total, 26 percent of the men and 28 percent of women were considered obese by the time they were 36, with obesity defined, according to National Institutes of Health guidelines, as having a body mass index (BMI) of 30 or higher.

Interestingly, the researchers say that among those who were obese by age 36, 80 percent were not obese between the ages of 20 and 22, although many had started gaining excess weight by that point.

Lead author Kathleen M. McTigue, a Robert Wood Johnson clinical scholar at the University of North Carolina School of Medicine, says that in looking at gender, ethnicity and body mass index, the researchers were able to actually predict who would become obese by their mid-30s.

"We made a statistical model, looking at a person's BMI and then adjusted for race and gender," she explains. "For instance, the larger women were at age 20 or 21, the greater a chance they had for being obese by the time they were in their mid-30s."

That seems logical, McTigue adds, but what she found striking was that women of all races didn't even have to be tremendously overweight to have a high risk of later becoming obese.

"Being even mildly overweight at age 20 or 21 put women at a much higher risk of being obese in their mid-30s," she says.

The findings appear in tomorrow's Annals of Internal Medicine.

While there are many theories, McTigue says it's still not known why obesity rates are higher among blacks and Hispanics or why those groups appear to become obese faster than whites.

Yet another perplexing pattern in the statistics involved significantly faster rates of becoming obese among those born in 1964 compared to those born just seven years earlier, in 1957.

"People born in 1964 who became obese did so about 25 to 27 percent faster than those born in 1957," McTigue explains. "That was really surprising to see. We can't offer an explanation for this, but it's been suggested that certain societal shifts in diet and exercise patterns may play a role."

Obesity expert Carol Boozer says one of the most important societal shifts that has probably boosted obesity rates is the settling of many Americans into sedentary lifestyles.

"If you go to a grocery store and see all the low-fat products, or sit in the park and see all the runners going by, you may think, 'How can we have a problem with obesity in this country?'," she says.

"But the fact is, there are so many more people sitting inside, working at computers all day long, and children sitting and playing computer games or watching TV, rather than playing outside," she says.

"For the vast majority of Americans, life is just much more comfortable than it's ever been, and there's less demand for physical exertion in our society than ever," Boozer adds.

Indeed, statistics appear to fall in line with the introduction of television and computer technology in society. According to the Centers for Disease Control and Prevention (CDC), the prevalence of obesity in American adults between ages 20 and 74 has doubled during the past 40 years, rising from 13 percent to 27 percent of the population. Sixty-one percent of U.S. adults now are either obese or overweight.

Lest we fall into a "fat and happy" mindset, the CDC warns that even being overweight (having a BMI of 25 or above) can place people at increased risk of a wide array of health problems, ranging from diabetes and osteoarthritis to stroke, coronary heart disease, congestive heart failure and even some types of cancer.

Seeing such strong patterns of obesity emerging in people of all races between their 20s and 30s should offer important clues in understanding obesity and how to treat the disease, McTigue says.

"Obesity is clearly a big problem in children, but it's also increased dramatically in adults. And our findings that most of the people didn't become obese until they were adults is something that should be considered by health providers," she says.

What To Do

Visit the Centers for Disease Control and Prevention for more information on your Body Mass Index or check out our heathtools.

The National Heart, Lung and Blood Institute, a branch of the National Institutes of Health, offers this helpful site on Healthy Weight Information for Patients and the Public.

Visit the http://www.surgeongeneral.gov/topics/obesity/ U.S. Surgeon General for more information on obesity.

Reference Source 101

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