My observations:
Fat girls don't run... they hobble.
Many people have a misconception: you run to get strong and slim down. It should be the other way around: you get strong and slim down FIRST, then you start running. Otherwise not only is it inefficient, it also kills your joints.
And if you want to slim down, don't stuff your mouth. Too many people want to 'reward themselves' with a hearty meal after an exercise session.