Craig Gundersen, a professor of agricultural and consumer economics at Illinois, says food and exercise alone are not to blame for the extent of obesity among children in the United States. Psychosocial factors, such as stressors brought about by uncertainty about the economy, income inequality, and a fraying social safety net also must be considered, he says.

"Energy-in, energy-out is important, but energy imbalance isn't the only thing leading to overweight status among children," said Gundersen, the executive director of the National Soybean Research Laboratory at Illinois. "We also know that people have very different ways of responding to the same amount of food intake and exercise, and one of the factors that may influence how people react to eating and exercise is through the amount of stress they're under."

Gundersen says stressors are particularly prevalent for low-income children, a demographic group that has high rates of obesity in the U.S. and other developed countries.

"As a society, we're always looking for different ways we can address public health issues, whether it's reducing food insecurity or reducing obesity," he said. "Although there have been many different ways to reduce obesity, what we've found is that stress is a leading cause of obesity among children. So if there's any way we can reduce stressors from a policy standpoint, that will also have the effect of reducing obesity."

The calls for trimming the social safety net that are currently in vogue in Washington, D.C., as part of a larger program of government austerity would likely lead to more obesity over time because it places more stress on low-income families, Gundersen says.

"If we cut back on benefits for the Supplemental Nutrition Assistance Program, or otherwise reduce its availability to people, that would increase the amount of stress that low-income families would face, which would then subsequently lead to increases in obesity," he said.

According to Gundersen, programs such as SNAP play a vital role in the social safety net as well as in efforts to end obesity.

"I really cannot stress how great of a program SNAP is," he said. "It's a fantastic program, and I think it can do a lot to help in our fight against obesity as it's currently constructed."

But there have been calls to restrict what SNAP recipients can purchase. For example, New York City recently proposed prohibiting children from purchasing sports drinks with their SNAP benefits. Gundersen views this development as setting a "dangerous precedent."

"Ultimately, placing restrictions on what people can buy only discourage them from participating in the program because it stigmatizes the benefits," he said. "The best way to reduce obesity isn't to introduce more restrictions, but to expand SNAP as it's currently structured."

Since SNAP allows families to purchase more healthy foods that they would otherwise be able to, any further restrictions or cutbacks to the program would have a two-fold effect, Gundersen says.

"Reducing access to SNAP would increase stress, which leads to increases in obesity, but it also means that families wouldn't be able to afford healthy foods and would subsequently have to purchase less healthy foods," he said. "When thinking about these sort of policy considerations, we have to think about who bears the brunt of these cutbacks, because not only could they lead to more obesity, but also to more inequality."

Gundersen says that while many families who are facing tough times may not be eligible for SNAP, which is only available to those below 130 percent of the poverty line, private food assistance networks can also play a key role in helping reduce food-scarcity stress.

"People know that if they're short on funds at the end of the month, they can go to their local food pantry and get some food," he said. "So a lot of people may be ineligible for SNAP but are still facing a very a stressful financial situation. Food banks really help those people, which in turn lowers stress and, by extension, obesity."

As many families face financial hardship as a result of the sluggish economy, Gundersen says that public policymakers need to be aware of the relationship between stressors and childhood obesity, which has only become more pronounced as income-inequality has grown over the last three decades.

"If present trends of income inequality are maintained, and if people are stressed by this -- and there is some evidence to suggest that they are, to the extent that it's your position versus others in society, and not your absolute level of income -- that, too, could lead to more obesity," Gundersen said.

The study, published in the journal Obesity Reviews, was co-written by Duhita Mahatmya, Steven Garasky and Brenda J. Lohman, all of Iowa State University.

The research was supported by the U.S. Department of Agriculture.