A new study suggests that motorists are on average four kilos heavier than people who use bikes as their main form of transport.
Researchers from Imperial College London have collaborated with colleagues from across Europe in a study which has monitored the movement of 11,000 volunteers.
They were asked how much time they spend travelling and what mode of transport they use.
Analysis of their height and weight show that those who use cars as their main form of transport are on average four kilos or 8.8 pounds heavier than those who get about by bike.
The EU-funded study is called the Physical Activity through Sustainable Transport Approaches project - or PASTA.
As well as London, volunteers from six European cities are taking part in the study including Antwerp, Barcelona, Orebro in Sweden, Rome, Vienna and Zurich. More people are needed to help researchers draw firmer conclusions.
Researchers also hope to establish what leads people to make decisions about their mode of transport and the impact this has on their health.
Anyone who wants to take part in the study can sign up at the PASTA website.