[arvidj]

While what you say is true, taking public transport makes people move around more: going to/from the bus-stop, changing at connections, standing up in the metro instead of sitting etc.

Here is a study on this subject: http://www.bmj.com/content/349/bmj.g4887 Its conclusion: "Men and women who commuted to work by active and public modes of transport had significantly lower BMI and percentage body fat than their counterparts who used private transport."