LOS ANGELES - A new study suggests the price of fresh fruits and vegetables has a stronger connection to weight gain among children than whether they live near fast-food outlets.

It adds more confusion to the muddy picture of what causes youngsters to gain weight.

Advocacy groups have suggested a strong link between obesity and the proximity of fast-food restaurants or the lack of supermarkets stocked with fresh food. But the new study by the Santa Monica-based Rand Corp. think tank found little support for that connection.

"You see lots of stories about the poor becoming obese because they're in neighborhoods with lots of restaurants and no access to healthy food," said Roland Sturm, a co-author of the Rand study. "We show that well, maybe those stories don't hold up."

The study examined the weight gain of 6,918 children of varying socio-economic backgrounds from 59 U.S. metropolitan areas as they advanced from kindergarten to third grade. Researchers compared the weight gain figures with the price of different types of foods and the number of food outlets in the areas.

They did not examine what the children ate, however.

The results showed that young children who live in communities where fruits and vegetables are expensive are more likely to gain excessive amounts of weight than kids who live in areas where produce costs less. That connection was stronger than the proximity to fast-food restaurants.

On average, children in the study gained 29 pounds. But for the region with the highest relative price for produce - Mobile, Ala. - children gained about 50 percent more excess weight as measured by body-mass index (a ratio of height to weight) than children nationally.