Again I haven't tried it, so just guessing what would be the result based on my experience baking fat free. Fat-free doesn't work always. It's more of a trial and error experiment. Personally I wouldn't suggest baking it entirely fat free, because you might end up with a dry bread. So start with maybe 1/4 cup of unsweetened applesauce and 1/4 cup of softened butter/margarine or about 2 tablespoons of oil. See how it turns out and based on that you may decide to reduce the fat content further.