Genetics or just bad eating habits might not be increasing America's waistlines. A new study suggests that individual choices may have little impact on the rise in number of people who are obese.

Researchers say that it might have to do with "collective behavior" in humans.

For the study, researchers used data provided by U.S. Centers for Disease Control Behavior Risk Factor Surveillance Systems for 2004 through 2008 to find spatial co-relations between environment and obesity.

According to the researchers, Greene County, AL, is the epicenter of the obesity epidemic. The Appalachian Mountains and the Mississippi River valley are two clusters that have emerged from the epicenter.

The states neighboring these regions have a high prevalence of obesity in BMI terms. A BMI greater than 30 is considered obese.

The study also says that the regions that have higher concentrations of food related businesses tend to have higher prevalence of obesity.

"We found there is a relationship between the prevalence of obesity and the growth of the supermarket economy. While we can't claim causality because we don't know whether obesity is driven by market forces or vice versa, the obesity epidemic can't be solved by focus on individual behavior," said Hernán Makse, physicist, City College of New York said. Makse is the lead author of the study.

As obesity is seen to be associated with market demands and social behavior, it has leapt out of the genetic factors to factors relating to environment. Researchers, however, say that this isn't a causal relation but a co-relational one.

Obesity is growing with an incredible pace in the U.S., which according to certain estimates is, with more than 30%. Men and women across all ages and ethnicities are prone to obesity but non-Hispanic black (44.1%) and Mexican- American men (39.3), especially those with higher income, are more likely to be obese.

The World health Organization says that now almost 65 percent of the world population lives in countries where more overweight or obesity kills more people than underweight.

"The basic idea is that if a non-communicable disease is spreading like a virus, then environmental factors have to be at work. If only genetics determined obesity, we wouldn't have seen the correlations," he said.

The study is published in the journal Scientific Reports.