Obesity is still on the rise among California students, but after years of prevention measures in schools, the rate is slowing, new research shows.

More than 35 percent of students were overweight or obese in 2008, up from one-third in 2003. That’s an average annual increase of 0.33 percent, compared with 0.8 to 1.7 percent each year in decades prior.

The findings, released last week, are based on the results of state-mandated physical fitness testing of fifth-, seventh- and ninth-grade students. Researchers at UC Davis, with funding from the California Department of Education, examined test results of 6.3 million students over six years.

The tests showed overall improvements in aerobic capacity, upper body strength and flexibility and declines in healthy body composition, abdominal strength and trunk extensor strength. The percentage of students achieving healthy fitness in all categories jumped from about 29 percent in 2003 to nearly 35 percent in 2008.

“This is a first step. It’s a big first step because for the first time, we’ve at least been able to block the progression or increase in obesity,” said Dr. William Bommer, a professor of cardiovascular medicine at UC Davis and senior author of the study. “Obesity, it’s probably one of the hardest things we have in adults and even in kids to try to reverse.”

Student Obesity Rate Slowing Thanks To Prevention Efforts In Schools