My cat Clyde is a shameless glutton. He will eat anything at all. He has to be fed separatly from all the other animals, otherwise he inhales his food, and then tries to bully food from the other cats.
He is a very small cat though, not much bigger than a kitten. I had always wondered why he was so small, a friend has one of his litter mates, and that cat is huge, at least 20 pounds. Turns out Clyde was the runt of a litter of 12. And his first owner was neglectful of him, he was an 8 week old kitten and was fed only once a day.
I really believe that he still feels like he has to eat as much as possible in case he doesn't get any food. He never got over the early trauma of being neglected.