SWITCHING from public transport to travelling to work by car is associated with an average weight gain of one kilo per person (just over two Ibs in old money).

That was the finding of a recent study in England into the health benefits to commuting by foot, bike or public transport.

Unsurprisingly a shift in to opposite direction was linked to a "statistically significant" reduction in weight - as much as seven kilos (a stone) for those with a journey time of more than 30 minutes.

You would be forgiven for having missed it though - the embargo was lifted at 11.30pm on May 7 when newspapers and broadcasters were gripped by another breaking story.

So, with the dust settled, it is worth giving the study - published in the Journal of Epidemiology and Community Health - another look.

The proportion of people in England and Wales who commute by car has increased from 42 per cent to 67 per cent over the last 40 years, and researchers at the University of East Anglia and the Centre for Diet and Activity Research (CEDAR) set out to determine whether they could quantify the impact on workers' waistlines.

Scotland is no better, with the most recent Scottish Household Survey finding that 67 per cent of Scots also commuted by car.

The findings are based on the responses of 4000 people to three waves of the British Household Panel Survey (BHPS) in 2004-5, 2005-6, and 2006-7.

The BHPS is a long term annual study of a representative sample of adult Britons which began in 1991-2.

At each time point, respondents described their usual main mode of transport for their daily commute, and provided details of their height and weight - used to calculate body mass index (BMI).

The researchers used a series of analyses to see if changes in mode of transport were linked to changes in weight over a two year period from 2004/5 to 2006/7.

In short, they found that those who had switched from a car to walking, cycling, or public transport - usually a bus or coach - lost an average of one kilo (2.2 Ibs).

The longer the commute, the stronger was the association. Commuters with a journey time of more than 10 minutes typically shed two kilos (4.4 Ibs) while those travelling more than 30 minutes to work lost an average of seven kilos (more than 15Ibs).

In comparison, switching to a car was associated with an average weight gain of around one kilo per person.

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.

The researchers suggested that if policymakers made it easier for commuters to make the switch to walking, cycling and public transport it could reduce the level of obesity at population level.

With 27 per cent of Scots clinically obese as of 2013 and obesity costing Scotland an estimated £4.6 billion a year, major investment now in walking, cycling and public transport infrastructure could pay dividends for the nation's health in future.