The path to obesity may actually be a highway from one community to another. It may have more to do with the collective behavior of a geographical area and its food marketing and distribution patterns than the poor food choices of an individual or their genetic make-up.

A group of researchers, led by City College of New York physicist Hernan Makse, had previously theorized that collective behavior was a bigger factor in obesity than lifestyle choice or genetics and decided to further investigate this hypothesis by using physics and statistics. County-level data was analyzed from the U. S. Centers for Disease Control and Prevention Behavior Risk Factor Surveillance System for the years 2004 through 2008 and compared to food centers and the supermarket economy in that area.

A higher number of food establishments corresponded to higher rates of obesity.

A map of obesity prevalence in the United States showed that neighboring geographical areas tend to be similar in their rates of obesity. Greene County, Alabama was pinpointed as the center of the obesity epidemic; and two other clusters were found, one along the Appalachian Mountains and the other in the lower Mississippi River Valley. These clusters were compared to certain characteristics: prevalence of adult obesity and diabetes, cancer death rates, economic activity, and population density.

The researchers found "clustering patterns" of obesity that they determined resulted from "collective behavior, which may not merely be the consequence of fluctuations in individual habits." The obesity clusters were compared to the presence of supermarkets, food and beverage stores, restaurants, and bars, and the researchers found that a higher number of food establishments corresponded to higher rates of obesity.

The World Health Organization (WHO) considers obesity a global health epidemic and one of the greatest public health challenges of the 21st century. It is a non-communicable disease for which no prevention strategy has been able to contain the spread.

Correlations between environmental factors and obesity would not have been observed in their research if only genetics determined obesity, said Makse. When a non-communicable disease spreads like a virus, environmental factors must be at work.

The study does not claim to show that obesity is caused by geography because it is not known if obesity is driven by market forces or if it is the other way around, but Makse does believe that the current epidemic of obesity won't be solved by focusing on individual behaviors.

The WHO's position on the obesity epidemic is that, "Both societies and governments need to act to curb the epidemic. National policies should encourage and provide opportunities for greater physical activity, and improve the affordability, availability and accessibility of healthy foods. They should also encourage the involvement of different government sectors, civil society, the private sector and other stakeholders."

The study was published online in the journal, Scientific Reports.