People looking to lose weight on the way to work should take public transport, as they can benefit from the ‘incidental’ physical activity involved, according to a major new study published in The Lancet Diabetes & Endocrinology journal.

Experts at the London School of Hygiene and Tropical Medicine looked at data from more than 150,000 Britons aged between 40 and 69, in the largest study to date on the health benefits of active transport.

They discovered that people who walk or cycle to work have a lower body fat percentage and body mass index (BMI) than those who drive.

And even those who travel on public transport have lower BMI and percentage body fat than car drivers, with researchers stating that the “incidental physical activity involved in public transport journeys has an important role.”

The strongest associations were seen for adults who cycle to work, compared to those who drive, with men 5kg lighter and women 4.4kg lighter on average. Walking to work was the next strongest association in reducing BMI and percentage body fat. But the study adds: “Even individuals who reported a mix of public and active methods were also found to have significantly lower percentage body fat and BMI than those who exclusively commuted by car, with a similar size of association seen for the walking only and the mixed public and active transport categories.”

Compared with car users, men who used public transport weighed 2.2kg less; and those who mixed public transport with walking or cycling were 3.1kg lighter. For the average woman in the study travelling to work in either of these ways, the weight differences were 1kg and 2kg respectively.

Many people live too far from where they work for walking or cycling to be a practical way of travelling in. But active commuting, where individuals walk or cycle part of their journey, is a “way to increase population physical activity without requiring unacceptable financial or time expenditure,” according to the study.

Lead researcher Dr Ellen Flint, an expert in population health at the London School of Hygiene & Tropical Medicine, said: “We found that, compared with commuting by car, 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.”

She added: “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.”

Commenting on the findings, in an accompanying editorial, Dr Lars Bo Andersen, Sogndal and Fjordane University College, Norway, said: “Physical activity during commuting has health benefits even if its intensity is moderate and the commuting does not cause high heart rate and sweating.”

Justin Varney, interim deputy director of health and wellbeing, Public Health England, said: “Physical activity can play a role in maintaining a healthy weight, and helps to prevent or manage over 20 long term conditions such as coronary heart disease, diabetes and some cancers. Walking and cycling are some of the easiest ways for people to incorporate physical activity into their daily lives and it is never too late to start. People who don’t get the recommended levels of activity can incorporate walking into their lifestyle as a healthy start.”

“For people with disabilities, being able to access public transport easily encourages them to lead a more sociable and active life.