Last year, our younger son and his cat moved in with us for 5 months while he house hunted. Our other son and daughter-in-law decided we needed our own cat, and one of d-in-l's friends had a cat which needed a new home (after getting him 3 years before, they then got a hyperactive dog, then she had a baby and the cat was totally ignored). So they persuaded us to take him. In the last 4 months he's changed from a cat who just lay there and let the dog jump all over him, to a cat which now has a quality of life. It's been lovely to watch him come to life again.
But yes he is fat. The last but one owner (who had to rehome him as their child proved to be allergic to him) gave the last owner packs of food - which included porridge made for human consumption.