Research Activities, August 2013
Preventing Childhood Obesity—Researching What Works
When describing just how complex it is to study interventions for childhood obesity prevention, researcher Sara Bleich, Ph.D., takes a cue from the classroom and turns to the alphabet.
"Typically if you're looking at a community-based intervention for obesity prevention, you can't just say, ‘If you change A, what happens to B?' Usually what happens is you change A through J, and you have to figure out what happens to K," explains Bleich, associate professor of health policy and management at Johns Hopkins. "It's complicated to tease out the individual impact of different things." But she tries.
"Obesity is something that we don't entirely understand. We know that people are getting bigger because they either eat too much or exercise too little. But the complex things that are driving that relationship are not entirely understood," says Bleich. "When you combine that with a disease whose etiology we don't totally understand, it's a messy topic."
More than 20 researchers at Johns Hopkins University, including 9 affiliated with the Johns Hopkins Evidence-based Practice Center, tackled that topic in their systematic review of childhood obesity prevention programs, which was supported by AHRQ's Effective Health Care Program. Several of the researchers spoke with Research Activities.
The AHRQ review, Childhood Obesity Prevention Programs: Comparative Effectiveness Review and Meta-Analysis, analyzed childhood obesity interventional studies that aimed to improve diet, physical activity, or both in many settings, including schools, homes, primary care clinics, child care settings, the community, and combinations of these settings in high-income countries. More than 80 percent of the studies were conducted in school-based settings.
A comprehensive approach
"In measuring the effectiveness of community-based programs that impact childhood obesity, more comprehensive interventions are definitely better," says Bleich about the review. "The research shows that to help prevent obesity among children, we must focus on both diet and exercise in the communities where children live and go to school since the environment is a key contributor to obesity risk. Focusing on the community is especially important for children since they generally have little or no control over their environment."
Principal investigator of the AHRQ-funded project, Youfa Wang, M.D., M.S., Ph.D., has devoted his career to preventing obesity and has authored more than 130 publications. He is the founding director of the Johns Hopkins Global Center on Childhood Obesity. He says, "This is an important systematic review in our field. We examined various childhood obesity prevention studies published over the past three decades and we focused on high-income countries. The majority of the childhood obesity prevention studies were school-based. We found modest to strong evidence that school-based interventions can help reduce children's risk of obesity. Our review provided a number of important insights to help guide future research in the field and guide future intervention programs. For example, very limited studies have tested environment- and policy-based interventions. More future research in this area is needed."
Experts in the field from other institutions, including universities, health departments, and government organizations, contributed to this systematic review by providing comments and suggestions on the review protocol and the 800-page evidence report. The review called for more studies on the effectiveness of interventions in a variety of settings other than schools.
In the United States, 17 percent of U.S. children and adolescents are obese, and approximately 30 percent are either overweight or obese, according to national survey data. Minority groups, such as African Americans, Hispanics, and Native Americans, and low-income groups are at higher risk of obesity.
A personal issue
Wang also understands the complexity of the issue on a personal level. "In my own house, we notice a difference in our two young boys–who are both very healthy. But my wife and I are a little concerned about one of them regarding his body weight. My sons have the same parents and live in the same household, but they have different tastes and personalities," he explains. "We care and we have the knowledge to make a difference. Compared to what we know how some other parents provide meals and snacks to their children, we see the differences we have made in helping our children to eat a healthy diet." Yet, Wang acknowledges the interaction between genetics, culture, environment, and many other factors play a role in obesity.
"My doctor says. . ."
Researcher Nakiya N. Showell, M.D., M.P.H., says that this research combined with her other ongoing research and clinical experience have broadened her perspective and changed the way she counsels her patients and their families. "The perspective I have on the factors that influence what a child eats and how much they play has changed," explains Showell, a pediatric fellow in the Division of General Pediatrics and Adolescent Medicine and incoming assistant professor at Johns Hopkins. "Some things are beyond a family's control. There may be limited access to healthy foods and vegetables and they can be difficult to afford. I'm not just saying to my patients that you need to limit your screen time, play outdoors, and eat fresh fruits and vegetables every day without asking questions like—‘Where do you buy food? Are you able to get healthy foods where you live? Can your child get a healthy meal at school? Are you able to pack a lunch for your child?' I'm starting to ask the questions first before I give the guidance and tailoring my counseling because I have a better understanding of what could affect one's obesity risk."
Showell shared a story about one of her patients, a normal-weight baby she had been caring for since birth. "At around age two, her BMI [body mass index] skyrocketed above the 95th percentile for weight, so she was technically obese. I had a very open discussion with her parents and I told her parents that I was very concerned. We talked about diet, physical activity, and more. They looked at me a little bewildered because they had never been asked these questions," says Showell.
When Showell followed through with recommendations, she made sure they were culturally sensitive. "I told them, ‘I don't want you to change all your family traditions. There are ways to do what you're doing in a healthy way.' I followed her for months and her weight was on a much healthier trajectory, and her BMI was much better. When I asked the parents, they told me that when their daughter would tell people, ‘My doctor says I can't have any soda,' and ‘My doctor says I can't have too many tortillas,' they really responded. Rather than just saying, ‘no,' the little girl says, ‘My doctor says.'"
Beyond body mass index
Researcher Lawrence J. Cheskin, M.D., F.A.C.P., started a weight control program at Johns Hopkins in 1990. He primarily sees adults, but he is very interested in preventing obesity in children. "It is extremely difficult to change people's body weight," he says. "It is extraordinarily difficult to fight the headwinds of our society that has promoted obesity in our children. We have a lot to do to truly tackle this epidemic." Yet, Cheskin is hopeful. "The most effective way we can tackle obesity is preventing it in children," he says. "There are favorable factors when it comes to children. One is that, for better or worse, they are much more under our control than adults are. An eight year old can't jump in the car and go to the fast food store and use a credit card."
Cheskin tells about one of his patients, a 10-year-old girl he had been seeing, who presented him with a handmade card made out of blue construction paper. "We spent hours together. Her parents were involved along with a dietician, an exercise specialist, and a psychologist. Later, she sent me this lovely card thanking me for helping her. She told me that it was so hard being overweight because kids made fun of her, and she was looking forward to not being made fun of anymore," he explains.
"This was hard to hear, because as adults we don't usually do that sort of thing or at least we would recognize how cruel and unfair it is to judge a person based on their weight. This had nothing to do with the health consequences of obesity. It's about how we treat other human beings with problems. She'll feel better about herself after losing weight, even though the judgment is not fair. She should not feel bad about herself. She is not defined by her body weight. But that's the reality of our culture. No matter how many of us are obese, we still have this bias and prejudice."
For Cheskin, his work is about this 10-year-old girl and children like her. "Most everyone cares about our children and the world's children," he says. "We need to devote more resources and make obesity prevention a priority as a society. This will have a lasting effect for generations to come."
Editor's note: You can access the review at the Effective Health Care Program Web site at http://www.effectivehealthcare.ahrq.gov.