Are you sure that the gain is fat? It could be muscle and bone. How do your clothes fit? How is your belly? Is it getting flatter?
Three hours of cardio six days a week, if that is what you are saying, is way too much. If you mean a total of 3 hours per week, that is different. It still should be less than full out cardio except for a couple of short sprint sessions.
What meats do you eat? Do you eat variety cuts or just lean?