We have the same problem with our cat but as he is 18 it's age related. He has been cleared of any illness by the vet.
He drove us nearly demented with constant crying for food. No sooner had he eaten than he was tripping us over in the kitchen for more. It was endless. In desperation I was giving him more food to basically shut him up
It failed as he ate it and was then sick.
We have now excepted it's age related and confusion. What is working at the moment is buying some cheap cooked chicken and chopping it up very small and adding it to a pouch of food. Then I have found myself giving him a little saucer of single cream ( I know ) if he starts crying again. Seems to fill him up so he will finally go to sleep. I have put a cat bed in the spare room and now put him in and shut the door.
I have read age makes a cat just forget they have eaten. Our boy is also showing signs of being confused when outside so keeping him in now. Hope you find a solution for you both.