Many suggest before restricting calories, you "up" activity. Personally, depending on how "fat" you are, i think cardio 6x a week would be a bit much, IF in fact you are training intensely. When in a calorie deficit, it is hard enough to take your ass to the gym, let alone add in 6 sessions of cardio. Psychologically draining. Calorie-in Calorie-out is the gist of weight loss, but if you start reading, it becomes quite complicated. Consuming too few of calories for extended periods of time will destroy your metabolism, which in turn could cause weight gain in the long run. I'd highly suggest reading through the article ive posted (through the link) as well as the other articles that Dr. Berardi has posted on that same page.
personally.. I tried huge calorie deficits, 1400kcal per day, (maintenance is like 3400kcal) only to find that deficit leads to binges, which destroyed my physique. finding a "diet" that you can adhere to day-in & day-out for weeks (maybe months) as a time is key. People whom lose weight quickly through radical diets can not maintain, and end up gaining it all back.
READ, READ, IMPLEMENT, TRAIN. good luck buddy
*** I personally have become a HUGE fan of IF (intermittent fasting). I'd suggest looking up Martin Berkhan, or site searching "intermittent fasting" here. has done wonders for me