You can also feed them less, and then put that kibble in the treats as part of dinner time. So they'd get half their dinner from the bowl and half from a puzzle toy, or whatever.
Cat nip. It sounds like they want treats and a puzzle just happens to be in between them and sweet sustenance. We have 3 cats and when they get to begging, my god, I'm out numbered and out matched. Our girl is on a diet so snacks are a no-go for now but a little bit of fresh nip and POOF! Now I have distracted cats for a good half hour. Play time has officially begun.