"Switching to public transport or cyclingwalking to get to  work might help shed the  pounds Strengthens case for incentivising walking or cycling to boost  population health say researchers Switching from driving to work to using public transport  walking or cycling might help commuters shed weight within a  couple of years suggests res earch published online in the  Journal  of Epidemiology  Community Health . Given that car use is high the findings strengthen the case for  incentivising walking or cycling to boost population health  suggest the researchers. They base their findings on t he responses of  people to  three waves of the British Household Panel Survey BHPS in        and   . The BHPS is a long term annual study of a representative  sample of adult Britons which began in   . At each time point respondents described their usual main  mode of transport for their daily commute and provided details  of their height and weight BMI in    and in   . The researchers used a series of analyses to see if changes in  mode of transport were linked to changes i n weight over a two  year period. In the first analysis which included  respondents   people had stopped driving to work and were either walking  orcycling  or taking public transport . The switchers tended to be younger and less likely  to have  access to a car than those who continued to drive. Those who chose to walk or cycle instead tended to have a  lower household income and a shorter commute  which  became shorter still after making the switch  while those who  opted for public transport were significantly more likely to be  more highly educated. Switching from a car  to walking cycling or public transport  was associated with a statistically significant average reduction  in BMI of . kgm after taking account of other influential  fac tors  equivalent to a difference of around  kg a person on  average. The longer the commute the stronger was the association with  a reduction in BMI of . kgm equivalent to a weight loss of  around  kg associated with journeys of more than  minu tes  and . kgm associated with journeys of more than   minutes  equivalent to weight loss of around  kg on average. In the second analysis which included  people   switched from active to passive travel. Some  stopped  walkingor cycling an d  switched from public transport  usually a bus or coach to the car. Once again the switchers tended to be younger than those  who continued with their mode of transport. Those who stopped walking or cycling to work were significantly  less likely  than those who stopped using public transport to be  in a managerial or professional post. They also tended on  average to have a shorter commute which lengthened after  the switch. Those who had previously used public transport on the other  hand had a  short commute after the switch. But switching to a car was associated with a significant weight  gain of around kg per person or . kgm  after taking  account of other influential factors. This is an observational study so no definitive conclusions can  be drawn about cause and effect. Nevertheless the analysis of  individual level changes in BMI over time between the two  groups of switchers using data from a nationally representative  survey strengthens their findings say the researchers. If a la rger proportion of commuters were able to abandon their  cars for a more physically active commute this could help drive  down the average population BMI they suggest. Combined with other potential health economic and  environmental benefits associated  with walking cycling and  public transport these findings add to the case for interventions  to promote the uptake of these more sustainable forms of  transport they write.  Research Impact of changes in mode of travel to work on  changes in body mass  index evidence from the British  Household Panel Survey  httpjech.bmj.comlookupdoi.jech     About the journal The Journal of Epidemiology  Community Health is one of  more than  specialist journals published by BMJ. The title is  the official journal of the Society of Social  Medicine. httpjech.bmj.com"