Just gotta get them (the kitties, at least) onto a paleo diet. Take the grains out of their canned and dry food and a few junk food treats won’t do any real damage.
Doesn’t have to be that expensive either. A nongrain dry food is a bit more, but much of the supermarket pate cans (e.g., Fancy Feast or Friskies) is generally grain-free.
Cats are obligate carnivores. They need a protein based diet. Unfortunately a lot of less expensive cat foods are laden with carbs.