Systems and methods for making a middle distillate product and lower olefins from a hydrocarbon feedstock

A method comprising:

• catalytically cracking a gas oil feedstock within an FCC riser reactor zone by contacting under suitable catalytic cracking conditions within said FCC riser reactor zone said gas oil feedstock with a first catalyst to yield an FCC riser reactor product comprising a cracked gas oil product and a first used catalyst;
• contacting a intermediate reactor feedstock with a second catalyst within an intermediate cracking reactor operated under suitable high severity cracking conditions so as to yield a cracked intermediate reactor product, comprising at least one lower olefin compound, and a second used catalyst;
• separating said cracked intermediate reactor product into a lower olefin product, comprising said at least one lower olefin compound;
• wherein the intermediate reactor feedstock comprises at least one of a fatty acid and a fatty acid ester.