Is Your Car Making You Fat?

Last Editorial Review: 8/25/2005

How to break the drive-everywhere habit

By Leanna Skarnulis
WebMD Weight Loss Clinic - Feature

Reviewed By Cynthia Haines, MD

"My car is making me fat" sounds about as plausible as "My dog ate my homework." But don't laugh. The truth is that the lack of physical activity in our daily lives is a huge contributor to obesity. And what contributes more to inactivity than our dependence on the automobile?

A recent study of the link between driving and obesity showed a result that surprised even its lead researcher: Every 30 minutes you spend each day in a car increases your risk of being obese by 3%.

"Three percent for a half-hour is a heck of a result," says Lawrence D. Frank, PhD, who led the Georgia Institute of Technology study involving nearly 11,000 Atlanta-area residents.

The study also showed that:

  • 90% of participants reported not walking at all. The average person in the study spent one hour or more per day in a car (driving or riding). Some spent more than five hours.
  • People who lived in neighborhoods with shops and offices within walking distance were 35% less likely to be obese than people who lived in sprawling, residential-only suburbs.
  • An average white male (height 5'10") living in a compact community with nearby shops and services weighed 10 pounds less than a similar white male living in a low-density subdivision.
  • Three out of every four people using mass transit had to walk to or from a stop, and were likely to get the surgeon general's recommended 30 minutes per day of physical activity.
  • For the average study participant, each kilometer walked (that's just over a half mile) per day translated into an almost 5% reduction in the probability of being obese.

A Matter of Mindset

We live in a nation with the world's lowest gas prices. Many of us are in the habit of driving or riding everywhere. So if your car is sabotaging your weight control efforts, what can you do?

"Get into the mindset of 'I could walk that,'" says Susan Moores, RD. "Something like 80% of our car trips are 1 mile or less. We need to stop and think about walking or biking to buy stamps or pick up a movie." She adds that rising gas prices might help us do just that.

Experts say there's a definite correlation between walking and weight management.

"It depends on the type of walking you do," says Moores. "Walking to or from your car probably has little effect, but if you're walking ... for more than three minutes, it has a positive effect. Also, walk briskly, so you feel somewhat breathless but can still carry on a conversation."

Help! I Live in Suburbia

How easy it is to get out of your car and walk often depends on where you live.

"Some places, it just isn't safe," says Moores. "Drivers aren't used to seeing bike riders or pedestrians. They're preoccupied with talking on their phones."

Still, it isn't a lost cause, she tells WebMD. She offers these tips for walking more wherever you are:

  • Park some distance from work or from a store and walk the rest of the way.
  • Park on the perimeter of every parking lot you use.
  • Use stairs instead of elevators.
  • Walk for 15 minutes at lunchtime.
  • Try to walk 15 minutes every three hours during your workday. "The blood will go to your brain and make you more productive," she says.
  • If you love to shop, do a couple of laps around the mall before strolling through the shops.
  • Wear a pedometer. "It puts a number to your accomplishments so you can track your progress," Moores says.

Where You Live

The Georgia Tech study didn't analyze the attitudes behind participants' behavior.

"We don't know whether people are sedentary because of where they live or if sedentary people choose to live in environments that aren't walkable," says Frank. "Also, do people trade off living in walkable places for other reasons, like schools or crime rates?"

Frank and his family moved to Vancouver from Atlanta and chose a walkable neighborhood.

"We like to walk, and we're more physically active than we were in Atlanta where the environment wasn't walkable," he says.

Where are you likely to find walking-friendly neighborhoods?

"Often, any neighborhood built before 1950 is walkable," Frank tells WebMD. "Also, in college towns it's easy to walk or bike."

Walking-Friendly Environment

Moores, who has a nutrition consulting business in Minneapolis/St. Paul, says creating a more pedestrian-friendly environment will take a commitment from developers and communities.

Some companies with workplace wellness programs offer bonuses for people who don't use the parking garage, or for people who wear pedometers and record a certain number of steps.

Others make cars available during the workday to encourage people to use mass transit or to park some distance from work. That way, a car is available if an employee needs to go to a meeting during the day or respond to a family emergency.

Many city planners are now adopting "Smart Growth" designs for land use that promote livability. Smart Growth includes preserving natural environments; developing new areas as mixed-use neighborhoods of shops and residences; and providing transportation systems that accommodate pedestrians, bicycles, and mass transit as well as automobiles. One-third of suburban respondents in the Georgia Tech study said they would prefer to live in a Smart Growth community.

On the federal level, former Health and Human Services Secretary Tommy Thompson called for "complete streets" to help fight the obesity epidemic, saying, "Every road being built, you should be able to walk on it or ride a bike on it."

A Walking City

Brian Gabrial, PhD, got rid of his car when he moved from Minneapolis for a job in Montreal a year ago. It wasn't a sacrifice. Even in Minneapolis, he often left his car at home, preferring to walk and ride the bus.

"In Montreal, practically everybody uses mass transit," he says. "All bus lines feed into the subway system, making it possible to get anywhere in the city, and it's cheap. I buy a one-month pass for the equivalent of $50 U.S."

Most days he walks the 1 1/2 miles from his apartment to Concordia University, where he's an assistant professor of journalism. In bad weather, he takes the bus.

The biggest hardship? "It's not practical if you're buying a lot of groceries," he tells WebMD. "On the other hand, most stores will deliver."

In a city where pedestrians are the norm rather than a novelty, crossing streets is safe, says Gabrial. "Also, in Montreal drivers can't turn right on a red light," he says.

Several years ago, the 53-year-old professor decided to substitute walking for running due to knee injuries. He walks for exercise as well as for getting around his neighborhood.

"It definitely contributes to my ability to manage weight," he says. "I don't have to diet. But I also subscribe to the algebra theory of living, so if I'm shoveling a lot of junk into my mouth, I need to walk more or spend more time in the gym."

He adds, "There aren't a lot of fat people here."

Published Aug. 12, 2005.

SOURCES: American Journal of Preventive Medicine, August 2004. Lawrence D. Frank, PhD, associate professor, J. Armand Bombardier Chair, Sustainable Transportation Systems, School of Community and Regional Planning, University of British Columbia, Vancouver. Susan Moores, MS, RD, spokesperson, American Dietetic Association; nutrition consultant, Minneapolis. Brian Gabrial, PhD, assistant professor of journalism, Concordia University, Montreal.

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