Melanie Konarik heard the warnings from her school “lunch ladies”: the students at the Texas district where she serves as the director of child nutrition would never go for fat-free milk and whole-wheat rolls.
But with little fuss, the children of the 31,300-student Spring school district, near Houston, took to the healthier options, along with chef salads, pizza with lowfat cheese, and eggrolls that are baked instead of fried. The gratifying change reminded Ms. Konarik of why she switched, early in her career, to working with children instead of adults.
“This was a field where I thought I could make an impact,” she said.
But while school nutritionists are working hard to introduce healthy choices to schools, and districts are implementing federally mandated wellness programs, the strongest research into the effects of lower-fat food and fitness for students in schools shows that the efforts often do little to make overweight children less fat.
Research shows that children can learn healthy-living options, such as the importance of exercising vigorously and eating fresh fruit and vegetables. But the influence such information will have on them as they grow up can only be measured down the road. And, while some researchers have attempted to introduce family-nutrition education as a component of their studies, the effects such education has on children’s well-being is even harder to discern.
Carl-Erik Flodmark, the chief of the childhood-obesity unit at University Hospital in Malmo, Sweden, was the primary author of a report this year that examined various studies around the world related to interventions to prevent childhood obesity. He and his co-authors examined the results of 24 studies that involved 25,896 children.
Their findings, published in the International Journal of Obesity: Eight studies showed positive effects in reducing obesity and 16 showed neutral effects. When he examined the conclusions of other reviews of childhood obesity research, he came up with 15 studies with positive results and 24 with neutral results.
Those 15 studies, though not the majority of the ones examined, at least demonstrated that some interventions work, Dr. Flodmark said in an e-mail message.
“However, there are no patterns giving us any clues [into] what is the difference between successful interventions and less successful [ones]. This shows that you need to focus more on the methods used,” he wrote.
A 2005 report published in the Cochrane Database of Systematic Reviews, a British journal that reviews health studies, offered similar conclusions after examining 22 research studies.
“The mismatch between the prevalence and significance of the condition and the knowledge base from which to inform preventative activity continues to be remarkable,” concluded the report, written by researchers at the University of Teesside in Middlesbrough, England. “At a time in which we see obesity prevention nominated as a public-health priority, we have only a limited number of studies from which to examine findings.”
Multiple Health Risks
Leslie A. Lytle, a professor and researcher at the University of Minnesota-Twin Cities’ school of public health, has worked on some of the best-regarded studies on efforts to prevent childhood obesity.
“We have little pieces of research,” Ms. Lytle said. “We do not have the community trial that shows we’ve done all this, and this is what works.”
But none of this suggests that children should consume as much candy as they want, all while watching hours of television each day, she stressed.
“We have to move forward based on the best evidence we have,” she said. “We can’t wait. Things are sort of spiraling out of control.”
Few experts would deny that childhood obesity is a problem. According to a study conducted by researchers at the U.S. Centers for Disease Control and Prevention, in Atlanta, the prevalence of obese young people in 2000 was 15.3 percent among 6-through 11-year-olds and 15.5 percent among 12- through 19-year-olds. In 1980, only 7 percent of 6- through 11-year-olds and 5 percent of 12- through 19-year-olds were considered obese.
Obesity is defined for children and adolescents in a different way than for adults. Though the body-mass index, a measure of body fat, is used for both children and adults, there are no government tables of healthy weight ranges for children and adolescents as there are for adults, because healthy weight varies as a child ages and grows.
But far too many children are at the higher end of the weight scale, researchers agree, and children with weight problems are at risk of developing psychological burdens, as well as physical consequences such as diabetes and hypertension.
The prevalence of overweight youths among ethnic minorities is even higher, in some cases. In one three-year-study, researchers tried to determine whether they could prevent American Indian children from becoming overweight by launching an extensive study of 1,704 3rd, 4th, and 5th graders in 41 schools with majority-Indian populations in Arizona, New Mexico, and South Dakota.
The Pathways study, which was conducted in the 1990s and whose findings were published in the American Journal of Clinical Nutrition in 2003, tried to tackle the program comprehensively. Children received lessons on healthy eating and physical activity. Food-service workers were taught how to purchase and prepare lower fat school meals. A minimum of three 30-minute recess sessions were offered to children each week. Family information packages were sent home to parents, and family fun nights were held at schools, all focused on healthy living.
At the end of the study, researchers found that students had significant knowledge of healthy food choices, and that they tended to eat less fat, compared with a control group. But the children in the intervention group didn’t lose weight.
Beyond the Classroom
Another project, the Child and Adolescent Trial for Cardiovascular Health, or CATCH, study, examined 5,106 children at 96 schools in California, Louisiana, Minnesota, and Texas in the early 1990s. As in the Pathways study, children were taught about healthy food, offered opportunities to exercise in physical education class, and given a home curriculum to share with their parents.
The results, published in 1996 in the Journal of the American Medical Association, showed that after three years, children ate less fattening school lunches and reported engaging in more vigorous exercise. Blood pressure, body mass, and cholesterol measures were similar between the children who were receiving the interventions and those who were not. A follow-up report on the children three years later showed that the CATCH children tended to exercise more than those in a control group, but that they still had no significant differences in body mass compared with a control group.
Many researchers suggest that children’s lives must undergo widespread environmental changes that go beyond the classroom. The Institute of Medicine, a part of the National Academies, said in the report “Progress in Preventing Childhood Obesity: How Do We Measure Up?” released in September, that the problem must be tackled by governments, communities, industries, and families, as well as schools.
Alicia M. Moag-Stahlberg, the executive director of Action for Healthy Kids, a Skokie, Ill., health-advocacy group, says there’s no need to wait for definitive studies when common sense suggests that less fat and more exercise helps young people with their weight. The right thing is to make healthful choices easy for students, she believes.
“It is very, very difficult to do school-based intervention studies,” said Ms. Moag-Stahlberg. “But I don’t believe that we need to do that. I believe there is enough evidence that, personally, I don’t need to do a study that says, ‘Will it work?’ ”
“We’re talking about a major social change that has to occur,” she said. “By no means is it all on the families and the parents, and by no means is it all on the schools.”
Coverage of education research is supported in part by a grant from the Spencer Foundation.
A version of this article appeared in the October 18, 2006 edition of Education Week as Effects of Schools’ Push for Healthy Eating Unclear