Monks do this reflection before taking food:
‘Wisely reflecting, I use alms-food not for fun, not for pleasure, not for fattening, not for beautification, only for the maintenance and nourishment of this body, for keeping it healthy, for helping with the Holy Life; thinking thus, I will allay hunger without overeating, so that I may continue to live blamelessly and at ease.’
You can do the same before you eat.
You can also be mindful while eating as mentioned in the Mahasi Sayadaw Satipatthana technique.