Science Diet is one of the worst dog foods on the market. It's full of fillers and by-products. She's eating and eating because she is hungry. You really should consider home cooking. It's the best and safest. Here is some info on dog food:
Dead Cats And Dogs Used To Make Pet Food Closer Look At A Rendering Plant The Dark Side of Recycling
The best book I highly recommend on this very subject is, FOOD PETS DIE FOR by Ann N. Martin.