'Tis the poundage-prone time of year. Holiday food and too much celebration can really cause problems. As you begin to contemplate the New Year resolutions to combat this yearly threat, you might want to consider a new tactic suggested by a mathematician, rather than a dietician: Leave your car keys at home.

Your weight is a product of your daily caloric intake and output. So, a group of University of Illinois researchers reasoned that reducing how much you eat or how much you use the car can affect your body mass index (BMI). “…Making small changes in travel or diet choices may lead to comparable obesity reduction, which implies that travel-based interventions may be as effective as dietary interventions,” said graduate student Banafsheh Behzad, a co-author of the study in a press release.

Even choosing to take the bus rather than the car and walking the distance to and from the bus stop could have an impact roughly equal to eating 100 calories less per day.

Instead of focusing on obesity as a product of the amount of energy consumed or energy expended, the group looked at the problem mathematically and nationally. Research has shown that people who are overweight spend more time in the car. So they decided to use driving as a measure of physical activity.

“An easy way to be more physically active is to spend less time in an automobile. Any time a person sits behind the wheel of a car, it's one of the most docile activities they can do in a day,” said Sheldon H. Jacobson, a computer science and mathematics professor who led the study.

Using national data on average BMI, caloric intake and driving habits, the team developed a mathematical model that took into account multiple variables and showed how calories consumed and miles driven correlate with BMI. The model predicted that if all adults in the United States drove one mile less per day, the average BMI would be reduced by roughly the same amount as if we all decided to cut 100 calories out of our diets every day for three years. Put that way, walking a mile — or a half mile out and back — doesn't sound particularly painful.

“One mile is really not much.” said Behzad. Even choosing to take the bus rather than the car and walking the distance to and from the bus stop could have an impact roughly equal to eating 100 calories less per day.

The benefits of hanging up the car keys extend beyond individual waistlines. Think of the financial impact from using less fuel and healthcare cost savings if people nationwide used their cars less and walked more.

“The most important thing for people to learn from this study is that they have a choice,” Jacobson said. “One has to be just as careful about when you choose to drive as when you choose to eat. These small changes in our driving and dietary habits can lead to long-term significant changes in obesity issues. ”

The study appears in the journal, Preventive Medicine.