Birkat Ha-Mazon when not full

Q: Does one recite Birkat Ha-Mazon if I am still hungry because I am dieting?
A: Yes, one needs to recite Birkat Ha-Mazon even when hungry. Even though the Torah states: "And you shall eat, be satisfied and bless" (Devarim 8:10), the Rabbis established that even when you eat the amount of a "Kezayit" (volume of an olive), which is the size of a matchbox, one recites Birkat Ha-Mazon (Berachot 45a).