As a dietitian and breast cancer survivor, I would encourage her to eat a broad variety of foods that taste good to her. Finding foods that taste good can be a challenge, but she she should keep looking and trying foods that she might not normally eat. For instance watermelon tasted particularly good to me. When I couldn't find things that tasted good, I drank Carnation Instant breakfast for the overall nutritional value that it provided. I tended to eat pretty plain foods because highly spiced foods didn't agree. Once I finished chemo and radiation, it was several moths before most things were tasting good. There are some salad dressings that I still can't tolerate. For me, small frequent meals worked best. I also discovered my taste changed overtime, for example, something that tasted good one time did not taste good another time. The important thing is to keep eating and not worry about high fat, low carb, etc unless she has intolerances that need to be accommodated. There's plenty of time afterward to follow specific plans if she chooses to once she is finished with treatments.