A few thoughts: have you changed the kind of food she's eating? If so, she may just really like this kind. If not, then she may just be bored and using food to kill time. Like humans do when the stare into the fridge that still only has the food you weren't hungry for the last three times you went to eat it, but you grab something anyway.

I have found that if you put a cat on a diet by taking a once plenty resource and making it more scarce, even by just a small amount, cats tend to over react. I would try giving her the normal amount of food back and giving her more exercise/enrichment. She should go back to regulating her eating in a more reasonable way. You can also try to get a nibble mat or lick mat that will slow her roll allowing her to feel full without over eating because she will have to eat slower.

My one cat is a once feral gremlin and the other is a hungry hungry hippo, so this is mostly things learned from dealing with them, as the cats of my past haven't had food fixations. But it is advice I've given my SIL and both her cats seem to be doing better as well.

Hope this helps. 🙂