Reading the comments by Curator and Bella on my previous post has reminded me to go back to PetMD and read the final installment of her summary of the study about how we can influence the behavior of our dogs.
It seems that the way to get your dog to choose a smaller portion of food over a larger one would be to handle the food, especially if you move it to your own mouth. Okaayy...if I'm going to try that one, it's going to be on a night when Penny's not getting ox liver or chicken necks or raw fish. (Oh, I forgot, raw fish is the only protein she refuses to eat, especially if it has eyes. I don't blame her.)
PetMD said the fact we can influence our dogs to go against their own judgment means we have a great responsibility towards them. I agree.