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Riders Who Take Mass Transit Regularly May Lose Weight

Light rail commuters like these in Charlotte, N.C., lost weight by taking the train. Payton Chung/ hide caption

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Payton Chung/

Light rail commuters like these in Charlotte, N.C., lost weight by taking the train.

Payton Chung/

Using light rail regularly can actually make you lighter. Not the sitting and riding from home to work and back again, but all the walking in between.

A year after a light rail system in Charlotte, North Carolina, began running, commuters who took light rail to work regularly were 6.45 pounds lighter than the folks who drove, researchers found.

Factoring in the walk to the bus stop, the walk from the bus stop to the rail stop, and then the walk to work and back,  "It could add an extra mile a day [of walking] for the average rider. Over the course of year, that mile a day will translate into substantial loss of weight," says John M. MacDonald who co-authored the study.

The Charlotte-Mecklenberg area's decision to develop a nine mile track through a high density residential area to downtown gave MacDonald and his colleagues the opportunity to conduct a natural experiment. Before and after the line was built, they surveyed people who lived for some time near the lines being constructed.

They asked them how often they exercised, whether they felt comfortable going for a walk in the neighborhood, lived near a park, and of course, their height and weight, income and employment status.

Then the researchers waited until 2008, six to eight months after the Lynx South Corridor Light Rail Line had been completed, figuring that would give people the opportunity to regularly using the system.

"We actually see," MacDonald says, "what happens to people who on their own (volition) decide to use the system and reap some reward in weight maintenance and weight reduction."

People who used the system more than once a week for 8 months after the rail line was in place had a 1.18kg reduction in body mass index (BMI). That’s a loss of between 6.4 and 7 pounds for a person who's around 5'5''.

"That's a significant drop in weight," says MacDonald. "People who used the system also were less likely to become obese over time."  These were people who reported no significant changes in recommended physical activity rates in the initial surveys.

MacDonald, a criminologist, says it's important to create safe and attractive environments linking home, work and transit stops.

"The built environment can constrain or facilitate physical activity," he says.

"Understanding ways to encourage greater use of local environments for physical activity offers some hope for reducing the growth in the prevalence of obesity," says MacDonald.

The study will appear in the August issue of the American Journal of Preventive Medicine.