If you up your fatty food intake her fatty food intake goes up. DS2 did the same thing with me being on a dairy free diet. I was able to eat soy, so the loss was slower
Try adding oils to anything and everything. Extra oil to a serving of soups, pasta sauces, smoothies or anywhere is a good way to sneak fats in. And TBH I don't think it matters what oil. I've used peanut, olive, seaseme, coconut and hemp oils for DS2. Avocados are good fat veges. Nuts are ridiculously high in fats. Pack the butter/margarine onto your bread if you are still able to have both of them.
Those are the ones that come immediately to mind.