I live in Chicago and am well served by public transport.  I realize this is not true for many people.  But even with that, when I was 337 lbs, I drove everywhere.

Now that I’m at 210 lbs, I’m much more likely to take bus, train, and even a cab once I get downtown – given the cost of gas and parking, and the aggravation of driving in traffic, I often come out ahead.

People who use public transport generally lose about 6 lbs in a year – walking, climbing stairs, etc.