In the same way that some of us (including me, tbh) put on weight easily and others don't, I'm assuming the same is true with cats? Or is one of my cats finding another food source? I've got two and both of them are fed half a sachet of wet food a day, and then I leave down a bowl of dry food for them both to eat - I've not noticed one eating more than the other. The only treat food I do is dreamies - but I'd say that is only 2 or 3 times a week and the same amount to both. Cat one is quite big, has long legs and is the sort of cat who leaps gracefully onto high places. Cat two is quite small, has short legs and quite a chunky body and a really pronounced primordial pouch which swings a bit when she runs. She does not leap gracefully onto high places, but she can get wherever she wants to go! Both have free access to outside and Cat two probably goes out more than Cat one. I'm fairly sure that if I took Cat two to the vet they'd tell me to put her on a diet...