Adults who walk, cycle or use public transport to commute to work have a lower body mass index (BMI) and lower body fat percentages in mid-life than those who drive to work, a new study has found.

The UK researchers noted that while the results are not unexpected with people who walk and cycle, the fact that those who use public transport also have lower body fat and BMI measurements shows that even the incidental physical activity involved with this type of commuting, e.g. walking from a bus stop to your job, has some benefit.

The study involved data on over 150,000 people aged between 40 and 69, making this the largest study to date to investigate the health benefits of active transport.

The best measurements related to cyclists. The average man in the study was found to be 53 years of age and weighing 85.9kg (189lbs). Those who cycled to work were found to be 5kg (11lbs) lighter than those who drove. This is a BMI difference of 1.71kg/m2.

The average woman in the study was aged 52, weighing 70.6kg (155lbs). Those who cycled were found to be 4.4kg (9.7lbs) lighter, which is a BMI difference of 1.65 kg/m2.

After cycling, walking was linked with the biggest reduction in BMI and percentage body fat when compared to drivers.

However, even commuters who used public transport to get to work had a lower BMI compared to drivers, as did commuters who combined public transport with other active methods of travelling.

The link between BMI and active commuting still stood even after other factors were taken into account such as general physical activity, overall health and income.

The researchers said that as so many middle-aged people commute by car, encouraging a more active lifestyle could have major public health benefits.

"Physical inactivity is one of the leading causes of ill health and premature mortality. 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," commented the study's author, Dr Ellen Flint, of the London School of Hygiene & Tropical Medicine.

Details of these findings are published in the journal, The Lancet Diabetes & Endocrinology.