People who drive to work every day are packing on slightly
more weight than their colleagues who use trains, buses and
bicycles to get to work, even if they exercise in their spare
time, according to an Australian study.
"Even if you are efficiently active during leisure time, if
you use a car for commuting daily then that has an impact on
weight gain," said lead author Takemi Sugiyama of the Baker
IDI Heart and Diabetes Institute in Melbourne.
Among people in the study who got at least two and half hours
of weekly exercise, car commuters gained an average of 1.8
kilograms over four years - about half a kilogram more than
people who got to work another way, or who worked from home.
Of 822 study participants, only those who got enough weekly
exercise and never drove to work managed to stave off any
weight gain over the course of the study.
Participants who didn't get enough weekly exercise also
gained weight, but now much they gained wasn't tied to their
mode of getting to work, according to results published in
the American Journal of Preventive Medicine.
"Simply achieving the amount of moderate physical activity
otherwise recommended won't provide enough compensation to
overcome the effect of commuting for a long period of time,"
said Lawrence Frank of the School of Community and Regional
Planning at the University of British Columbia in Vancouver.
There are probably other factors at work that were not
considered in the study, noted Frank, who was not involved in
"People who have longer commutes tend to purchase a lot of
their food and run a lot of errands on their way to and from
work," which influence weight gain, he said.
In addition, 80 percent of car trips are non-commuting.
Previous studies that focused on total time spent in cars per
day have also found a link to becoming overweight or obese.
A 2004 study of adults in Atlanta, Georgia, found that each
additional hour of time spent in a car each day was
associated with a six percent increase in the chances of
In Australia, about 80 percent of working adults take a car
to work every day. In the United States, that figure is 86
"Commuting is a truly important predictor of obesity," Frank
Many of those people don't have another option, said
Sugiyama, noting that it's the responsibility of government
to provide public transport to and from work, and design
neighbourhoods where short walks are accessible.
"The message is, if possible try to avoid cars, but for many
people that sort of choice isn't available," he said.