Lets say I am taking in 3000 calories and I burn off 1000 calories during the day doing weight and cardio which means that I am on a 2000 calorie diet.

Would it not be easier to burn off about 500 doing cardio and lifting then just lose the other 500 calories by dropping them from the diet. This would mean I would start at 2500 calories instead of 3000.

Are there any pro and con things to doing it this way?

I guess what I am asking is can't you get the same results without busting your butt with tons of cardio...

Also if I am misunderstanding something please explain it to me.

This is the idea behind combining diet and exercise to create an ideal weight loss situation...

Cardio is great for nutrient partitioning, burning calories and for general cardiovascular health. But too much cardio is a bad thing - it can hinder fat loss, decrease lean mass and cause cortisol levels to become chronically high. So you don't want to go and bust your butt with hours of cardio a day.

Similarly, cutting calories is pretty necessary for weight loss - you have to burn more than you take in. And it is a lot easier to decrease input than it is to increase effort/output... However, especially in the case of females or smaller males, you can't create a huge calorie deficiency simply by cutting calories - not without starving yourself (and creating dietary nutrient deficiencies). So it is easiest to add in some cardio as well.

Basically, you create a calorie deficiency through a moderate level of calorie restriction and a moderate level of cardiovascular exercise....