Cat survived

Hello, I'm looking for answers. My 5 year old cat hid somehow in the house we moved from. We assumed she got out during the move because we couldn't find her. She is very timid and wasn't responding to our calls so we just gave up. The house remained vacant and the new owner would frequently go there to work on it but never saw her. On July 5th, 6 weeks later, she suddenly appeared inside the house. Mind you, there was no way for her to get outside so she had been there the whole time, in a completely empty house with no food and only trickles of water from a hose in the basement. My vet said she does have fatty liver and lost between 3-4 pounds but she is eating now and gaining strength. Tell me how she survived?