Some good news in the war on weight: Obesity in the United States may finally be stabilizing instead of increasing.
Even though the rates of obesity remain high, with about one-third of Americans still falling into that weight category. And, rates of obesity among already heavy 6- to 19-year-old boys appear to be increasing.
"Obesity still remains a significant problem that we need to deal with, but recent data suggests the increasing trend of obesity may be slowing down," said the lead author of one of the studies, Cynthia Ogden, an epidemiologist at the National Center for Health Statistics in Hyattsville, Md.
Results of the studies were being published online Jan. 13 in advance of print publication Jan. 20 in the Journal of the American Medical Association.
In an accompanying editorial, Dr. J. Michael Gaziano, from the Massachusetts Veterans Epidemiology Research and Information Center, wrote that these studies "offer a glimmer of hope that in the United States at least, the steady, decades-long increases in overweight and obesity may have slowed or perhaps reached a plateau. But even if these trends can be maintained, 68 percent of U.S. adults are overweight or obese, and almost 32 percent of school-aged children and adolescents are at or above the 85th percentile of body-mass index (BMI) for age."
The consequences of obesity are far-reaching. Excess weight is linked to type 2 diabetes, heart disease, stroke, high blood pressure, high cholesterol, cancer, joint disease, sleep apnea, asthma and other chronic conditions, Gaziano said.
After remaining relatively stable between 1960 and 1980, obesity rates steadily increased, according to government statistics gathered from 1988 to 1994 and again from 1999 to 2000.
The current studies included data from the National Health and Nutrition Examination Survey (NHANES) gathered from 2007 to 2008, which were compared with statistics from 1999 through 2006. One study focused on adults, while the other looked at children from infancy through the teen years.
The adult study found the prevalence of overall obesity was 33.8 percent -- 32.2 percent in men and 35.5 percent in women. The rates of obesity for women remained relatively stable during the study period. In men, however, the rates went up during the first five years and then leveled off.
"The increases in the prevalence of obesity previously observed do not appear to be continuing at the same rate over the past 10 years, particularly for women and possibly for men," wrote the researchers.
The risk of being obese increased with age, according to the study. The biggest increases came after age 40. Blacks -- both male and female -- and female Mexican-Americans were significantly more likely to be obese than non-Hispanic whites.
For the study on children, the researchers sorted the data into three different cut-off points, according to Ogden -- a BMI over the 85th percentile for age and gender, over the 95th percentile or the 97th. In general, over the 85th percentile is considered overweight in children, while over the 95th percentile is considered obese, according to the U.S. Centers for Disease Control and Prevention.
Overall, 9.5 percent of children under 2 had a BMI over the 95th percentile, and 16.9 percent of children between 2 and 19 had a BMI above the 95th percentile, according to the study.
It appears that the rate of obesity leveled off in 1999 in children and has remained steady since, with one exception. The researchers found an increase in the number of white boys between 6 and 19 years old whose BMIs were over the 97th percentile.
The researchers don't know why the rates of obesity might be increasing in this one group, because the study wasn't designed to find out the cause of such trends, only to spot them, Ogden said.
Anirban Basu, a health economist at the University of Chicago, said that many factors may contribute to the overall stabilization of obesity rates. "It is possible that the rise in calorie intake that we saw during the late 90s and early 2000s has flattened out," he said. "Better awareness does play a role, given the billions of dollars spent on obesity and diabetes awareness and also diet regimens."
"There are a lot of transitions happening at the individual level across all BMI categories. It's important to understand those transitions and, even if overall obesity proportions have stabilized, to think about targeted intervention," Basu added.