My cat Tito is the same way. I have come to the conclusion that whether or not he's really hungry, I know how much he needs to eat (according to vet's guidelines) because I'm his mommy! At least your kitty is still in shape - Tito only eats 1/3 cup of food a day & he's still fluffy.

They can make you feel guilty so easily - meowing, looking at the bowl - cats are masters of their craft!

My advice is to ask your vet how much he should be eating, and just stick to that. Good Luck!