Ummm, I think you should speak to the nutritionist again. People who are enzyme defiicient cant break down any long chain molecules, which include fats AND protiens. Whilst there may not be any fat in this type of food there is protien, and she will not be getting any of this protien from these foods which is exrtemely important in kids growing up.
The problem is, only short chain molecules can be absorbed through the large intestine walls. The enzymes in our food break down long chain molecules so that they can be absorbed. With out these enzymes, fats, oils, protiens and complex carbohydrates (not entirely sure about the carbs) are not absorbed and the patient suffers from malnutrition. It is especially important for kids growing up to get all the essential fatty acids and protiens they require, or they will suffer from stunted growth and all sorts of related problems.