Well, you need to feed her with the highest calorie food and to know that time burns calories, walking burns them more and the run burns them even more. The best food for weight gain is Coconuts from the start if you find enough of them. And also you should train cooking to make more dishes and choose the best options from them.
And do not forget to keep her full, so that she will gain capacity after sleeping, so you could feed her more food next time.