If you are really fat how can you lose fat fast?

You can loose a ton of weight by cutting out simple things from your diet. For me, I cut out soda and sugary drinks. Coffee, tea, and water are good, just watch your sugars. I also greatly limited my alcohol intake, and tried to do 30 minutes of just walking on a treadmill. You don't have to run, in fact running can be dangerous for the joints of an overweight person. This is a good start.