My cat is 6yrs old,weighs about 7 lbs she hates dry food won't eat any snacks and the only brand she will eat is fancy feast. I can open a can right now eat half of it and cry for food. I still leave it down she will then finish the rest. Then goes to sleep for as long as I don't go near that kitchen. After 10 min she is climbing all over me wanting more food. When I bring home cold cuts she will rip the bag loves table meats. Why is she constantly hungry ? Can't stand the crying so I give in.

Wow! She's got you trained!

We have four cats. That includes a new addition ("Deborah") that we brought in last week from the outdoors. Deborah already knows the sound of a Fancy Feast can being opened, and comes dashing into the kitchen to be first in line. We feed all four, and then they disappear to nap. If someone happens to go into the kitchen to open a can of soup or something for himself, all four cats suddenly reappear (just in case) and will whine and cry until another can or two of FF has been opened. They love Buddig chicken slices and deli ham and McNuggets (with the coating removed and carefully diced) and Arby's beef, so we give them small amounts of these foods when we have them. It seems like even a token amount is good enough. They will snack, and then nap some more.

We're trained too. (And no, they aren't "hungry" but can always eat a bit more.)

Mabye you feed him too much try dieting her and only giving her a amount of food after that.

mabye you feed him too much try dieting her and only giveing her a amount of food after that.
That's not correct. You don't "diet" a cat. Her problem is not eating too much. Her problem is that she begs for people food and prefers only Fancy Feast cat food. She's spoiled.