Childhood obesity rates have more than tripled since the 1970s. It is estimated that almost 19 percent of children between the ages of two and 19 years old are obese. If obesity rates continue to increase, medical costs attributable to obesity and related conditions, such as diabetes and cardiovascular disease, could be as high as $66 billion per year by 2030.

Where kids live — the kind of nearby food resources including restaurants and grocery stores — appears to play a role in this weight gain. A study of more than one million students in New York City found a connection between how close a child lived to healthy and unhealthy food outlets and their weight and body mass index (BMI).

For every half or full block further away students lived from sources of unhealthy food, obesity rates dropped between one and more than four percent.

The New York University researchers analyzed height and weight data from the annual FitnessGram assessment of nearly 1.2 million New York City public school students between the ages of five and 18. They looked at how a child's weight corresponded to how close he or she lived to unhealthy food outlets such as fast food restaurants and corner convenience stores or bodegas or healthy food outlets, defined in the study as supermarkets and wait service restaurants.

About 20 percent of the students living within a half-block (about 132 feet or 0.025 miles) of a fast food outlet were obese and 38 percent were overweight. Among those living within a half-block of a corner store or bodega, 21 percent were obese and 40 percent were overweight.

For every half or full block further away students lived from sources of unhealthy food, obesity rates dropped between one and more than four percent, depending on the type of food outlet.

A family's proximity to supermarkets and sit-down restaurants did not affect obesity rates. “This finding suggests the neighborhood ‘food deserts,’ with a limited supply of fresh fruits and vegetables, may contribute to childhood obesity in urban areas,” Brian Elbel, senior author on the study, told TheDoctor.

The impact of fast food availability on obesity rates was not surprising, Elbel said. Fast food is relatively inexpensive, so kids can afford it. And fast food outlets are often marketed toward children and young adults. Supermarkets and wait service restaurants did not affect childhood obesity rates as much compared to fast food and bodegas because kids often can’t afford to go to such places. “So it’s just how often they use these things,” said Elbel, an associate professor at NYU School of Medicine and NYU Wagner Graduate School of Public Service.

Parents might want to consider how the local food environment, particularly the proximity of fast food outlets, influences how often their family eats foods that are high in fat, calories and salt. Parents concerned about family members' health and weight might want to go a little farther out of their way if their family will have a choice of healthier food options for a comparable price, Elbel suggested.

The researchers hope their findings will inform policies to limit the number of unhealthy food outlets in neighborhoods with persistently high obesity rates. The team has already completed a study looking at the association of both home and school food environments and childhood obesity rates, and they are investigating the effect aspects of the physical environment, such as access to parks and transportation, have on childhood obesity rates.

The study is published in Obesity.