That's the unfortunate finding of a new study conducted at seven Philadelphia schools by researchers at Temple University and the Food Trust, a city-based nonprofit.

Nearly 70 percent of the 595 children surveyed said they bought food or drink from corner stores and other outlets while walking to or from school - $2.98 per day on average, much of it junk. The top three choices: chips, soda and candy.

The researchers were pleased to discover how many kids were traveling on foot - about 74 percent in the morning, 86 percent in the afternoon - but dismayed by the snacking, says lead author Stephanie S. Vander Veur, director of clinical research at Temple's Center for Obesity Research and Education.

Following the in-school survey, the researchers intercepted students as they emerged from stores and asked to see what was in their bags, says Vander Veur, who presented the findings at Saturday's annual meeting of the Obesity Society in Phoenix, Ariz.

Activists often bemoan the scarcity of fresh produce at stores in poorer areas such as these schools' neighborhoods. At each, more than half the student body was eligible for federally subsidized meals.

John Weidman, deputy director of the Food Trust, says he is encouraged because the nonprofit already has persuaded some corner stores to stock fruits and vegetables.

Still, junk often is cheaper. Corner stores sell off-brand colas for as little as a quarter, for example.

Says Weidman: "The kids can get really a lot of calories and a lot of sugar for two bucks."

- Tom Avril