April 10, 2012 -- Where you live may determine your child's weight, according to a series of new studies published this week.
In a special issue of the American Journal of Preventive Medicine, researchers from the U.S., Canada and the United Kingdom used geographic information systems (GIS) to look at how features of neighborhoods children live and play in affect their health.
What they found is that characteristics of the neighborhoods children live in could be contributing to the high rate of obesity in the U.S. and elsewhere.
In one study, researchers used geographic information to determine which neighborhoods in King County, Wash. and San Diego County, Calif. rated highest in terms of physical activity and nutrition for children ages 6 through 11. A neighborhood received a high rating if there were ample opportunities to walk to places, such as stores and libraries as well as highly-rated parks.
These neighborhoods also had numerous grocery stores or supermarkets where produce and healthy foods were available.
Neighborhoods that rated poorly had few markets available or had a large number of fast food restaurants and also did not offer many chances to walk or play in high-quality parks. There were also neighborhoods rated in between good and poor.
"The biggest difference we found in rates of obesity were in the places where the environment was good for both nutrition and physical activity, the rates were less than 8 percent, but if the nutrition and physical activity were not good, the rates went up to 16 percent," said Brian Saelens, a co-author and professor of pediatrics at Seattle Children's Research Institute.
Saelens added that researchers controlled for other variables that could contribute to obesity, such as income, family status and parental body mass index (BMI).
In an accompanying paper, Saelens and his colleagues used GIS data to define "obesogenic" environments as those that offer little in the way of physical activity and good nutrition. The authors say GIS measures should be used to assess the relationship between physical activity, nutrition and obesity.
By using GIS data, Saelens explained they were able to obtain objective, detailed information about how many parks, grocery stores and other places were in each of the neighborhoods.
Spatial technology, explained Stephen A. Matthews of Pennsylania State University, is rapidly becoming a valuable research tool.
"As GIS has matured (the ready availability of geospatial data, enhanced visualization tools, and advanced analysis methods), there has been an explosion of interest in the application and use of spatial concepts and methods in health-related research," Matthews wrote in commentary.
And in another commentary, Celeste Marie Torio of the Robert Wood Johnson Foundation wrote that while GIS-based research is still in its early stages, it may "help enhance our understanding of how the multitude of factors and their interactions influence childhood obesity, and help us reverse this epidemic."
GIS research still faces many challenges, wrote Janne Boone-Heinonen of the University of North Carolina at Chapel Hill and Penny Gordon-Larsen of Oregon Health and Sciences University, but it still holds a lot of promise for driving policies geared toward preventing and reducing childhood obesity.
Growing Body of GIS-Based Literature
In a study of adolescents from Halifax, Nova Scotia, researchers found that rural teens get most of their physical activity during school, while urban and suburban teens get most of their activity during their commutes to and from school.
Policies geared toward combatting childhood obesity should take the varied sources of physical activity into account, the authors argued.
"Policies developed to promote physical activity should sustain the walkability and active transport option in urban areas and, concurrently, improve and enhance options for youth outside of the urban core to engage in active commuting," they wrote.
In another study, British researchers took a look at the relationship between obesity and the consumption of fast food by using GIS data to assess how many fast food restaurants were within about a half-mile of the homes of 13-year-olds.
A higher body mass index (BMI) and more body fat were both associated with eating fast food.
Food choices, availability of recreation areas and other neighborhood features also played a role in obesity among adolescents in the Minneapolis/St. Paul, Minn. area.
A low percentage of recreation areas, as well as the perception that neighborhoods aren't safe, were linked to higher BMI scores in boys and girls. Other intermingling factors associated with obesity were low socioeconomic status, a high number of convenience stores and fast food restaurants, and a lot of mass transit.
Experts not involved in this research say neighborhoods' detrimental effects on health have long been suspected, but there has been little solid evidence to back up the claims. These studies, they say, provide important data.
"We can confirm things that logically seem to be true, but we didn't have extremely strong data," said Dr. Richard Jackson, professor and chairman of environmental health sciences at the UCLA Fielding School of Public Health. "The evidence base is only now becoming very robust." Jackson is also the author of several books on the topic.
City and town planning policies have moved toward promoting healthier lifestyles in the past decade or so.
California and some other states have laws in place requiring that new roads must be constructed with everyone in mind, meaning drivers, pedestrians, bicyclists and people with disabilities, Jackson said.
"There's been a huge shift in the public health community's awareness of the built environment and its impact," he said.
But others say while the environment does pose barriers to healthier lifestyles for children and adolescents, parents still must take measures to overcome them by making different choices.
"In New York City, for example, there are parks all over the place, but people decide they don't want to take their kids to the park," said Keith Ayoob, associate professor of pediatrics at the Albert Einstein College of Medicine in the Bronx, N.Y. "There are things that make healthy behaviors difficult, but that's true whether people are rich or poor, and they're not insurmountable. People have to pay more attention to it, and parents have to set limits on what kids eat or what activities they engage in."