we have 2 cats, they're brothers but they're different in every way. Their mosts noticeable difference is their weight, one is skinny, very choosy with his food, and the other is as fat as can be, literally stuffs himself all day long. The vet said he should go on a diet so we bought him light dry food. But it's a nightmare supervising their feeding, since they have different foods now, and share the same space, obviously. They nibble all day long and I can't spend my day checking which one eats what. As a result, Fatty is still fat despite having been on a diet for weeks now. Any tips ?