Encouraging people to switch from driving to work to walking, cycling or using public transport could help reduce the level of obesity in the population, according to new research from the University of East Anglia (UEA) and the Centre for Diet and Activity Research (CEDAR).
The proportion of people in England and Wales who commute by car has increased from 42% to 67% over the last 40 years. Against this background of increasing car dependence, the researchers found that switching from car commuting to active travel or public transport was associated with a reduction in body mass index (BMI), even over a relatively short time period of two years.
Lead researcher Adam Martin, from UEA’s Norwich Medical School, said: “It is well established that overweight and obesity are linked to a wide range of diseases, most notably type 2 diabetes, cancer, heart disease and stroke.
“This study highlights the potential to contribute to reducing the average weight of the population by helping commuters build regular physical activity into their daily routines, through walking, cycling and using public transport on the journey to work.”
The research team, from UEA, the University of Cambridge and the University of York, based their findings on the responses of over 4000 adults in three annual waves of the British Household Panel Survey (BHPS) collected between 2004 and 2007. People reported their usual main mode of travel to work each year, and their height and weight in the first and third years. The researchers then used a series of analyses to see if changes in mode of transport were linked to changes in weight over time.
In the first analysis, switching from the car to walking, cycling or public transport was associated with a statistically significant average reduction of 0.32 BMI units after taking account of other potential explanations. This equates to a difference of about 1 kg for the average person. While that is a relatively small proportion of their total weight, the longer the commute, the stronger the association. For those with a commute of more than 30 minutes, there was an average reduction of 2.25 BMI units, or around 7 kg for the average person.
In the second analysis, switching from other modes of transport to the car was associated with a significant average increase of 0.34 BMI units, again after taking account of other potential explanations.
This is an observational study, so the authors cannot draw definitive conclusions about cause and effect. Nevertheless, the key feature of this study is that the researchers were able to compare changes in weight over time between commuters who had, and had not, changed how they travelled to work. While the link between commuting and weight may seem intuitive, it has rarely been tested in a longitudinal study using data from a representative national survey in this way.
“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 support a larger proportion of commuters taking up these more sustainable forms of transport,” the authors write.
- Read the full paper: Impact of changes in mode of travel to work on changes in body mass index: evidence from the British Household Panel Survey. Adam Martin, Jenna Panter, Marc Suhrcke, David Ogilvie. Journal of Epidemiology and Community Health.
- For more information or to arrange an interview with Adam Martin, contact the UEA press office on email@example.com. Outside normal business hours, a duty press officer can also be reached on: +44 (0)1603 592352.
- This article is the second in a series of longitudinal studies by researchers at UEA and CEDAR using commuting and health data from the BHPS. The first, published in the journal Preventive Medicine in 2014, analysed data from 18,000 people to show that commuters who switched from car travel to walking or cycling benefited from improved wellbeing. In particular, active commuters felt better able to concentrate and less under strain than those who travelled by car. http://dx.doi.org/10.1016/j.ypmed.2014.08.023
- This article complements a recent cross-sectional study of UK commuters by Dr Ellen Flint and colleagues which was published in the British Medical Journal in 2014. That study found that men who commuted by active travel or public transport had BMI scores that were 1.10 and 0.97 units lower on average, respectively, than those of commuters who used private motor vehicles. The corresponding differences for women were 0.72 and 0.87 units respectively. http://dx.doi.org/10.1136/bmj.g4887
- The BHPS is a long term annual survey of a representative sample of adults living in Great Britain which began in 1991. BMI units are kg/m2. For the calculation of equivalent weight loss for an ‘average’ person we assumed an average man of height 176 cm tall, weight 86 kg and BMI 27.8, and an average woman of height 163 cm, weight 72.8 kg and BMI 27.4.