London School of Hygiene & Tropical Medicine

Adults who commute to work via cycling or walking have lower body fat percentage and body mass index (BMI) measures in mid-life compared to adults who commute via car, according to a new study published in The Lancet Diabetes & Endocrinology.

People who commute via public transport also showed reductions in BMI and percentage body fat compared with those who commuted only by car. This suggests that even the incidental physical activity involved in public transport journeys may be important..

The study, by researchers at the London School of Hygiene & Tropical Medicine, is believed to be the largest ever analysis of the health benefits of active commuting. It looked at data from over 150,000 individuals from the UK Biobank data set, a large, observational study of 500,000 individuals aged between 40 and 69 in the UK.

The strongest associations were seen for adults who commute via bicycle, compared to those who commute via car. For the average man in the sample (age 53 years; height 176.7cm; weight 85.9kg), cycling to work rather than driving was associated with a weight difference of 5kg or 11lbs (BMI difference 1.71 kg/m²). For the average woman in the sample (age 52 years; height 163.6cm; weight 70.6kg), the weight difference was 4.4kg or 9.7lbs (BMI difference 1.65 kg/m²).

After cycling, walking to work was associated with the greatest reduction in BMI and percentage body fat, compared to car-users (BMI difference 0.98 kg/m² for men; 0.80 kg/m² for women). For both cycling and walking, greater travelling distances were associated with greater reductions in BMI and percentage body fat.

Commuters who only used public transport also had lower BMI compared to car-users (BMI difference of 0.70kg/m² for men), as did commuters who combined public transport with other active methods (BMI difference 1.00 kg/m² for men; 0.67 kg/m² for women). The effect of public transport on BMI was slightly greater than for commuters who combined car use with other active methods (BMI difference 0.56 kg/m² for men).

The link between active commuting and BMI was independent of other factors such as income, area deprivation, urban or rural residence, education, alcohol intake, smoking, general physical activity and overall health and disability.

In England and Wales 23.7 million individuals regularly commute to work, 67% of commuters by car. In the study sample, 64% of men and 61% of women commuted by car, and only 4% of men and 2% of women reported cycling only or a mix of cycling and walking. Previous studies that have looked at the association between active commuting have tended to combine cycling and walking together with other modes of active commuting, which may understate the positive effects of cycling

With the majority of people in mid-life commuting via car, the authors say there are significant public health benefits in obesity reduction that could be realised by encouraging and incentivising a more active lifestyle.

Lead author Dr Ellen Flint, Lecturer in Population Health at the School, said: "Physical inactivity is one of the leading causes of ill-health and premature mortality. In England, two thirds of adults do not meet recommended levels of physical activity. Encouraging public transport and active commuting, especially for those in mid-life when obesity becomes an increasing problem, could be an important part of the global policy response to population-level obesity prevention.

"Compared with commuting by car, we found that public transport, walking and cycling, or a mix of all three, are associated with reductions in body mass and body fat percentage - even when accounting for demographic and socioeconomic factors. Many people live too far from their workplace for walking or cycling to be feasible, but even the incidental physical activity involved in public transport can have an important effect."

The study was funded by the UK Medical Research Council.

Publication

Ellen Flint, Steven Cummins. Active commuting and obesity in mid-life: cross-sectional, observational evidence from UK Biobank. The Lancet Diabetes & Endocrinology. DOI: 10.1016/S2213-8587(16)00053-X