"We are actually making a connection between fast food proximity to schools and obesity," Davis said in a telephone interview.
"Students who were exposed to nearby fast food have a higher level of body mass index -- they weigh more. They are more likely to be overweight and obese," he said.
For the study, Davis and colleagues examined the relationship between fast-food restaurants located within one half mile of schools and obesity among middle and high school students in California.
They took weight and dietary information from a statewide school survey between 2002 and 2005 and cross referenced the data with a database of top fast food chains located near each school.
"Overall, our patterns are consistent with the idea that fast food near schools affects students' eating habits, overweight and obesity," Davis and colleagues wrote.
They also found that students whose schools were located near-fast food restaurants eat fewer servings of vegetables and fruits, and drink far more soda than students at schools not located near fast-food restaurants.
The study could not determine why fast-food restaurants near schools have such an impact, but Davis said it likely goes well beyond access to burgers, fries and tacos.
"A nearby fast-food restaurant is really a hangout place for people to socialize," Davis said.
Editor:Zhao Yanchen