For the Holiday Special, Isabella's overworld sprite is already at fat state before dinner, same thing when interacting with her also before dinner as she and Brookes said the same thing as if they already ate.
Before: https://ibb.co/Ng0Z0Db
After (I've censored her new art, so it doesn't get spoiled): https://ibb.co/gTFWpkx
By the way, I hope to see more art for Isabella art in the future! And I also think you should add some new Christmas items since Polly and Luci don't have their presents for now.