Incorporating active travel into long commutes is associated with reduced body fat

Encouraging more active travel (walking and cycling for transport) is one promising approach to prevent obesity and related diseases. In this study, published online in Preventive Medicine, researchers at the MRC Epidemiology Unit and CEDAR looked at the relationship between active travel to and from work and body fatness.

What we did
We used data from 7,500 people living in Cambridgeshire who are participating in the Fenland study. The study collects detailed information about the health and lifestyle of participants including travel, diet, physical activity and body composition.Body composition was measured using a DEXA scan (Dual Energy X-Ray Absorptiometry), which is a special type of X-ray that allows us to determine overall and regional fat as well as lean mass and bone density. It gives information about not just the overall percentage of body fat and where it is distributed, for example the amount stored in peripheral areas such as under the skin or as  ‘visceral adipose tissue’ surrounding the organs in the abdomen.

What we found
Among those living less than five miles from work, we found that those who cycled to work had lower body fatness compared to those who drove to work. Among those living more than 5 miles from work, we found that those who incorporated some walking or cycling into their journey, compared to those who drove all the way to work, had lower body fatness. We also found those who walked or cycled for other types of journeys (such as shopping or errands) had lower body fatness compared to those who drove.For visceral adipose tissue the pattern was very similar to that observed for total body fat, with a lower amounts of visceral adipose tissue observed for those who incorporated physical activity into their commute, although the association for women living more than 5 miles from work who reported regular car-use was (marginally) not statistically significant after adjusting for other self-reported physical activity.

Why does it matter?
In the UK most people live too far from work to walk or cycle the whole way, but incorporating some active travel within the commute is beneficial. This is important for people choosing how to commute as well as policy makers and planners who influence how towns, cities and transport infrastructure develop.Visceral adipose tissue is sometimes described as ‘bad fat’, because it is strongly linked to the development of diabetes and heart disease. Our work provides a partial answer to how and why active travel reduces the risk of diabetes and heart disease.

Other factors to consider
We accounted for other factors that might explain any differences in body fatness, such as age, education, diet quality, smoking, alcohol consumption and other reported or measured physical activity.As our study is cross-sectional our results alone do not show that walking or cycling to work causes people to have lower body fat, although the findings are in keeping with other recent studies that show physical activity can reduce body fat.