When I was younger our indoor/outdoor (declawed) cats were suddenly gaining a lot of weight starting every spring and slimming down through the winter. We put the cats on a special diet, monitored how much food they got, forbid giving scraps at dinner or while snacking. After a year of this and it finally seeming to work through the winter, regular vet check up revealed one fat gained almost 2 pounds in a month since spring.
As we were bringing the cat home we ran into our neighbor, who asked where we caught the cat. We informed him she was our cat, and had been for 6 years. He had a eureka moment "So that's where that cat comes from!" Before laughing through an explanation of how he thought his daughters brought home a cat after being told no because every afternoon the cat was on their deck waiting for the girls to come out. Turns out once weather was good enough to sunbathe outside, the girls would take some meat and cheese out to the back deck and our cats came over to investigate, leading to the tradition of the neighbor girls constantly feeding our cats through the spring and summer, the cats only losing weight in the winter cause it was too cold to be out on the deck.
