London: People who drive cars as their main form of transport are on average four kilos heavier than those who cycle, according to a study. The researchers studied how different forms of transport relate to levels of physical activity, and consequently people's health. Researchers have so far monitored 11,000 volunteers in seven European cities, asking them how they move around the city, which mode of transport they use and how much time they spend travelling. The team also asked volunteers to record their height and weight, and to provide information about their attitudes towards walking and bicycling. "Our research shows that factors like urban design, how we move in cities, and the use of cars, bikes or walking could all play an important role in determining the level of people's daily physical activity,” said Audrey de Nazelle, researcher at the Imperial College in a statement. “Getting people to walk and bike as part of their daily transport modes is really an ideal solution to try to tackle this epidemic of physical inactivity," added Nazelle. The survey also aims to determine how people make transport decisions, and what measures cities can take to encourage walking and cycling. While the researchers cannot yet draw a causal link between the type of transport people choose and their weight, they said the initial results are intriguing, and hope that by following more people they can draw some firmer conclusions.