Americans are using nearly one billion more gallons of gasoline today than in 1960, and the reason is sitting right behind the steering wheel.

According to a University study, this significant increase in annual fuel consumption is due to weight gain in both men and women over the last four decades.

Since 1960, the average man has gained 25 pounds and now weighs 191 pounds. The average woman is up 24 pounds to a weight of 164.

“If we weighed as much as we did in 1960, we’d have consumed 938 million fewer gallons of fuel per year,” said Sheldon Jacobson, professor of computer science and co-author of the study.

Jacobson explained that the study does little more than put a figure on common sense.

“We quantified what everyone intuitively understands,” he said. “If you put more weight in a car, it requires more fuel to move your car around.”

Jacobson’s partner in research was Laura McLay, an assistant professor at Virginia Commonwealth University who at the time was Jacobson’s graduate student. In late fall of 2005, Jacobson and McLay examined government data, including 2003 statistics on the amount of gas used, the number of miles driven, and the average number of people in a car. The results, while somewhat expected, were nevertheless startling to the researchers.

“We were both surprised that we use so much fuel just as a result of the weight we’ve put on,” McLay said.

Her and Jacobson also agreed that the study does not aim to promote weight loss.

“It’s not our intention to change anyone’s behavior,” Jacobson said.

McLay clarified the real goal of the research.

“We’re just trying to raise awareness,” she said. “There are many results of obesity.”

Jacobson started the research because of rising gas prices were costing Americans an extra $2.8 billion per year. Each extra pound of body weight in a car is responsible for 39 million more gallons of fuel usage annually, which translates into almost $120 million spent per pound.

For an individual, the numbers are smaller: in one year, the typical driver could purchase 18 fewer gallons of gas by shedding 100 pounds.

“What we have here is a quantification of obesity in a new way, in terms of fuel consumption,” Jacobson said.

This correlation between health care and gas usage is not the only connection drawn by the study.

“(Our study relates) a homeland security issue with a public health issue,” McLay said. “It creates a link between people getting heavier and our reliance on foreign sources of oil.”

The study will be officially published in the upcoming October-December issue of the Engineering Economist but has already been noticed because of an earlier news release. McLay called this press a “double-edged sword,” stating that coverage is necessary to inform the public but that the study’s results are often misinterpreted. She explained that the study is purely numerical, devoid of the researchers’ personal opinions.

“Math doesn’t judge people, people judge people,” she said.

Regardless of the exact statistics, Jacobson agreed, saying that studies like his own all relate back to one thing.

“We have an obesity epidemic in this country,” Jacobson said. “(Our study) doesn’t mean very much more than that.”