Updated

More and more, fast-food restaurants are staking out locations within easy walking distance of schools, exposing children to poor-quality foods, according to a new study.

The findings add weight to the growing argument that the availability of high-calorie, low-nutrition fast foods play a role in the nationwide epidemic of obesity among children.

That's the conclusion of a new study by researchers at Children's Hospital Boston and the Harvard School of Public Health. The study appears in theAmerican Journal of Public Health.

Researchers show that on average fast-food restaurants were located less than 1 mile away from any school in Chicago. They estimate that fast-food restaurants were three to four times more likely to be within less than 1 mile from a school than what would have been expected had the restaurant been distributed throughout the city in a way unrelated to schools.

"This means that five days a week, we are sending our school children into environments where there is an abundance of high-calorie, low-nutritional-quality, inexpensive food," says researcher Bryn Austin, MD, of Children Hospital Boston's division of adolescent and young adult medicine, in a news release.

Healthy Lunches, Healthy Students

Poor Nutrition a Culprit

Nationwide during the past three decades, fast-food retail sales have increased 900 percent, from $16.1 billion in 1975 to $153.1 billion in 2004, according to the study.

Previous research done by the authors in conjunction with the U.S. Department of Agriculture found that almost a third of children and teens eat fast food on a typical day. Compared with days in which children do not eat fast food, they consume more calories, fat, and sugar and fewer fruit and vegetables, write the authors.

Kids Choose Junk Food in School

Obesity Rampant Among Youth

The percentage of young people who are overweight has more than tripled since 1980, says the CDC. Among children and teens aged 6-19, 16% (more than 9 million young people) are considered overweight. Being overweight and obese puts them at greater risk for many diseases including heart disease and diabetes.

The psychological ramifications can be debilitating as well. Children who are obese or overweight are often teased, which can lead to depression and low self-esteem.

In 2002, Austin and her colleagues compiled a comprehensive list of 613 fast-food restaurants in Chicago. They then created a separate list of 1,292 public and private kindergartens, elementary schools, middle schools, and high schools.

Each restaurant and school was assigned longitude and latitude coordinates and census tract identification codes. Using statistical methods, the researchers quantified the distances between schools and restaurants and calculated the degree of clustering. In Chicago, overall they show that:

—35 percent of schools had at least one fast-food restaurant within less than a third of a mile —Nearly 80 percent of schools had at least one fast-food restaurant within less than half a mile.

—A significantly greater number of fast-food restaurants were located within a shorter distance from a school than would be expected. They were three to four times more likely to be within less than 1 mile from a school than what would have been expected had the restaurants been distributed throughout the city in a way unrelated to schools.

"Our cities are saturated with fast-food purveyors. ... With the concentration of fast food even worse in school neighborhoods, our schools, parents, and policymakers need to take a serious look at this issue," Austin writes.

The study was supported by a grant from the CDC.

Changes for School Vending Machines?

By Patti Connor, reviewed by Brunilda Nazario, MD

SOURCES: Austin, B. American Journal of Public Health, September 2005: vol 95. News release, Children's Hospital Boston. CDC.