The rates of obesity in the U.S. are holding steady, despite ongoing efforts to curb the epidemic, according to two new reports, published online Tuesday in JAMA, The Journal of the American Medical Association. About 35 percent of adults and about 17 percent of kids were obese in the period from 2009 to 2010 (the most recent years for which data were available).

For most adults, these rates have remained about the same for more than a decade. But some groups—non-Hispanic black women and women of Mexican ancestry in particular—have seen an increased obesity rate since 1999. And, according to Katherine Flegal of the National Center for Health Statistics (NCHS) at the U.S. Centers for Disease Control and Prevention and her study co-authors, "We found no indication that the prevalence of obesity is declining in any group." For both men and women 20 years and older overall, mean age-adjusted body mass index (BMI) was 28.7, which is toward the upper end of overweight, sneaking toward the obese category.

For children, however, the story has been slightly different, according to the second study in JAMA. Boys, in particular, have been becoming obese at higher rates than girls in the past decade. And the most recent data shows 18.6 percent boys between two and 19 were obese whereas only 15 percent of girls fit this category.

The extra weight might start accumulating as early as infancy—or pregnancy. In 2009–10 nearly 10 percent of babies younger than 24 months weighed more than their length would dictate (a BMI, of sorts, for babies). Recent research has also suggested a mother's weight during pregnancy can influence her offspring's chances of becoming obese. The obesity risk also steadily increased with age: 12 percent of kids aged two to five years, 18 percent of kids six to 11 years, and 18 percent of kids 12 to 18 years were obese, according to the JAMA study.

"Obese children may be at risk for both short-term health consequences and long-term tracking of obesity to adulthood," Cynthia Ogden, of the NCHS, and her team wrote in their paper.

As with adults, the obesity burden is unevenly distributed among groups for young people. Almost one in four non-Hispanic black kids or teens were obese and about one in five Hispanic kids or teens suffered from obesity—compared with about one in seven white kids or teens.

The relative stability of obesity rates in the past decade suggests that it might not be headed for exponential increase, as many previous reports have suggested. Nevertheless, the current damage to U.S. health from obesity is already as heavy as that from smoking. And recent estimates suggest that obesity's many health consequences—from diabetes to heart disease—are running up an annual bill of $147 billion in health care expenses, which does not include other documented losses such as decreases in productivity and the quality of life.