Why was the fat important in the sacrificial offerings?


They shall remove all the fat, just as the fat is removed from the fellowship offering, and the priest shall burn it on the altar as an aroma pleasing to the Lord. In this way the priest will make atonement for them, and they will be forgiven.  Leviticus 4:31
            The “fat” of an animal (humans too) stores the excess calories that are processed in the body (from carbs and sugars).  This fat is back-up energy when the body needs more calories. 
            The priests removed the fat from the sacrifices.  They were not allowed to eat it, but burn it.  That burning created a smell.  When you smell hamburgers on the grill, that smell is the fat burning.  That aroma was pleasing to God.  Why?
The priest shall burn them on the altar as a food offering, a pleasing aroma. All the fat is the Lord’s.  Leviticus 3:16
            The fat represented the excess, the best tasting, the fuel of the land.  By surrendering it to God in a sacrifice, you are acknowledging where the abundance, the best, and the motivation/drive really comes from—God, not the land.