After getting used to Inara's eating habits, I simply cut down on the amount of food I was putting in her dishes. This cut down considerably on the overt waste factor. I weighed her daily for a little over a week to ensure that she was still eating enough. She was. I also give her "untouchables" (things she does not eat that are left in her dish) to the outdoor wild birds. They and The Squirrel love her leftovers, and since she is healthy I don't worry about the risk of transmitting something from her to them. My avian vet gives her birds' untouchable to the chickens. So very little winds up wasted.
Yes, there are always bits and pieces in the bottom of her cage, but not nearly like it was, once I began titrating the amount I was offering. She still is abundantly fed, just not over indulged. I give her smaller bits and pieces (she is a TAG so is smaller in general) of things and mix in a few bigger chunks of non-sticky fruits and veggies to give her some foot held bits, too. She won't eat a pellet to save her life and personally I don't blame her. She does eat Nutriberries though, and those I break in 1/2 and toss about 5 broken ones in her dry dish.