For the first time in more than three decades, obesity rates for white and Asian children are falling in California, and they seem to have leveled off for Hispanic kids - all good signs that public health campaigns aimed at keeping young people away from unhealthful sweets and fatty foods are starting to work, according to a UCSF study.

The bad news is that those programs don't seem to be reaching all children.

In particular, obesity rates are still climbing for black and American Indian girls. And the percentage of youths in the heaviest range - those whose body mass index puts them in the 99th percentile for their age and gender, according to fixed growth charts established by health officials based on 2000 data - is also continuing to rise.

The study, which is appears in today's edition of the journal Pediatrics, suggests that public health programs created to fight obesity need to become much more widespread, said Dr. Kristine Madsen, an assistant professor of pediatrics at UCSF and lead author of the study.

"The fact that we're seeing some decline suggests that the efforts we're making on policy levels are having an impact, which is great. What no one expected is it's driving a deeper wedge between racial and ethnic groups," Madsen said. "This is a call to action for policies that will be truly equally distributed among communities."

The study looked at BMI, or body mass index, numbers for more than 8 million California schoolchildren from 2001 to 2008. The children were in fifth, seventh and ninth grades, and were weighed as part of the state's school-based BMI screening program.

Improved school food

Obesity rates peaked in 2005 - the year when state and local public health officials started making significant changes in the food made available in public schools, including removing sodas from vending machines and emphasizing healthy, fresh food in cafeterias.

Since then, rates have either leveled off or declined for most ethnic groups, the study found. Aside from public policy changes, pediatricians said public and professional awareness about obesity has played a big role.

"We can attribute the plateaus to increasing awareness of pediatric obesity in families and communities. And there's been a consistent effort by pediatricians to identify overweight and obese kids," said Dr. Padmaja Padalkar, an assistant chief of pediatrics who specializes in working with overweight children at Kaiser Permanente San Jose Medical Center. "But this study also reminds us that we're far from being out of the woods."

According to the study, 20 percent of California schoolchildren in 2008 were obese - which means their BMI was at or above the 95th percentile in the government growth charts - and 3.6 percent were severely obese, or at the 99th percentile.

Serious health risks

The percentage of obese children didn't decrease much from the peak in 2005 - it only fell by about half of a percent - but it's still notable because obesity rates had been climbing steadily for more than 30 years.

But the rate of severely obese children hasn't fallen at all for boys, and continues to climb for girls. Black and American Indian girls in particular have yet to see any decreases in obesity rates. Only 1 percent of white and Asian girls were severely obese in 2008, but 4.6 percent of black girls and 4.9 percent of American Indian girls fell into that category.

What's especially troubling about the rates of severely obese children is that they face multiple, serious health risks - many of them are diabetic, or prediabetic, or are showing signs of hypertension. Some doctors said the UCSF study shows that more emphasis needs to be focused on treating young people who are severely obese.

"It's great that at least some groups are seeing plateaus and declines, but at least in Oakland, we are seeing greater disparities in severe obesity," said Dr. Lydia Tinajero-Deck, co-director of the Healthy Hearts Program at Children's Hospital Oakland. "I'm seeing 12-year-olds that weigh over 200 pounds. As pediatricians, we're trying to figure out how to treat hypertension in a 12-year-old."