Sheldon H. Jacobson of the University of Illinois in Champaign and students Douglas M. King and Rong Yuan analyzed annual vehicle miles traveled per licensed driver as a surrogate measure for a person's total sedentary time.
"If you look over the last 60-plus years, the automobile has become our primary mode of transportation -- so much so, in fact, we have literally designed our way of life around it. It is that energy imbalance that ultimately may lead to obesity," Jacobson says in a statement.
After analyzing national data from 1985 and 2007, Jacobson discovered vehicle use correlated "in the 99-percent range" with national annual obesity rates. Jacobson used annual vehicle miles traveled as a proxy for a person's sedentary time because inactivity is most obvious when sitting in a car.
"If we drive more, we become heavier as a nation, and the cumulative lack of activity may eventually lead to, at the aggregate level, obesity," Jacobson says in a statement.
"When you are sitting in a car, you are doing nothing, so your body is burning the least amount of energy possible and if you are eating food in your car, it becomes even worse."
The findings are published in the journal Transport Policy.