A UC Davis study has found that the rise in childhood obesity rates in California is slowing, which researchers think may be the outcome of improved nutrition and physical fitness programs in the state’s public schools.
In their February report, “Obesity and Physical Fitness in California School Children,” published in the American Heart Journal, the researchers found that between 2003 and 2008, the rate increased by a mere 0.33 percent per year among the California students in their study. National studies in prior decades, based on surveys, had shown childhood obesity climbing at somewhere between 0.8 percent and 1.7 percent per year.
The study examined 6.3 million student records provided by the California Department of Education for 5th, 7th, and 9th graders in each year between 2003 and 2008. The students’ names were masked so the researchers tracked each class from 5th to 7th to 9th grade rather than each individual student.
The researchers found obesity levels were stable and fitness levels improved in students in grades 7 and 9, said Dr. William Bommer, professor of cardiovascular medicine at UC Davis and co-author of the study along with Dr. Melanie Aryana and Zhongmin Li. Bommer credits state regulations implemented during the past decade that promote better nutritional standards and establish fitness requirements for school children.
Bommer was involved in creating California’s new fitness requirements, established in 1996, which require an average of 20 minutes of exercise a day for K–6 children and 40 minutes for students in grades 7 through 12. Before the standards were created, there were no requirements for physical exercise in school, he said. He was also active in the state’s new nutritional standards, which include banning sodas and candy bars from vending machines.
“Weight gain can be entirely explained by 200 extra calories a day (from a large soft drink), five days a week,” he said.
However, the study found that each year, the entering 5th graders were more obese than the previous year’s 5th graders. In fact, Bommer said, the 0.33 increase in obesity “was totally accounted for by the (more obese) group coming into 5th grade each year.” As those 5th graders continued on in school, they did not get any thinner, at least through the 9th grade — but they didn’t get any fatter either and their fitness levels improved.
“Children who were obese entering the 5th grade remained obese in subsequent years as well, despite improvements in school nutrition and fitness standards,” Bommer said.
Bommer was not able to view records before 5th grade, which is the first year that fitness tests are required. But he suspects that the increase in obesity revealed in 5th grade records examined by him and his colleagues actually occurred before students enter the school system. After they begin kindergarten, he believes, the better nutrition and fitness regimen in California schools keeps them from becoming more obese.
“Once they enter the school system, it’s not getting any worse,” he said. “It’s a first step, but a big first step,”
To lower the obesity rate, the state needs to make an effort to reach children earlier, he said. Bommer recommends fitness standards be implemented at an earlier age, ideally at the preschool level.
As the study noted, “Continued increases in early entrance (5th grade) clearly will require additional efforts directed at preschool and elementary students to completely stop and reverse this obesity epidemic.”
The records reviewed by the researchers included students’ body mass index (BMI) (calculated from a student’s height and weight) and measurements of skin thickness to determine how much fat lies beneath the skin. They also included the results of state-required fitness tests measuring students’ aerobic capacity and flexibility, as well as abdominal, trunk, and upper-body strength.
One of the most important findings of the study was a significant increase in children’s aerobic capacity, which is likely due to the new exercise requirements, Bommer said. More aerobic capacity has been shown to reduce the risks for heart disease and diabetes.
However, only 31 percent of the children were deemed fit in all the areas measured.
The authors expressed particular concern about their finding that more children in lower-income counties were less fit than their counterparts in higher-income areas.
“We clearly need to do more to ensure that children, regardless of where they go to school, are benefiting from the recommended health standards,” said lead author Melanie Aryana.
The study also found that ethnicity played a role. Latino students had about a 40 percent higher chance of being physically unfit than the average student, Bommer said. Pacific Islanders had a 46 percent higher chance. However, Asian students were 50 percent more likely to be healthy. Whites were also somewhat more likely to be fit, and Filipinos were about average. African Americans were somewhat less likely than the average student to be fit.
Bommer said another way to measure the impact of the state’s new nutrition and fitness requirements is by looking at neighboring states. The growth in obesity among California children has slowed since the new nutrition and fitness rules were implemented, yet surveys done in Utah, Arizona, and Nevada show childhood obesity rates are rising faster there, as well as nationally, he said.
At the same time, Bommer and his fellow researchers cautioned in their study:
Despite the fact that progress has been made, much more is needed. Although the rise in obesity rates seems to have slowed down, our current efforts have not yet reduced obesity in children.
They also pointed to the crucial role of parents:
It is important to note that successful prevention of childhood obesity cannot be carried out by governments or educators alone, but that parents have to be heavily involved in the process by making changes in the home.
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