Fast-food outlets were located within about a half-mile of eight of the 11 schools, according to the survey, and 10 schools had stores nearby that sold soft drinks.
However, the researchers' statistical analysis found no correlation between a risk for being overweight and the proximity of fast-food restaurants to the teens' respective schools.
"This finding suggests that maybe we should be doing more to educate kids as to the impact of unhealthful food," Blum said.
Lona Sandon, a registered dietitian and assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center at Dallas, said that the findings were "surprising, yet not surprising."
"Knowledge is power," Sandon said. "Offering the knowledge of what foods are health-promoting and beneficial is certainly the first place to start. But behavior based on knowledge and the built environment both impact food choices. The question is, what has the biggest impact?
"In this case, they're saying the built environment around these teens is less impactful than what the children know about nutrition, and also less impactful perhaps than what's going on in the home," she said.
The home environment, Sandon stressed, plays a critical role.
"Past research has looked at what students bring to school when they bring their own lunch, and it's actually often less nutritious than if they ate a school lunch, which means that what's going on in the home is often worse in terms of giving kids a sense of what to do in terms of making healthy food decisions," she said. "And that might explain these findings."
Sandon suggested that "if we focus on informing kids as to how best to think about what they're eating, that may be a more impactful way to affect their decisions than trying to change the built environment around them."
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