CarbQuick
Carbquick is my flour substitute of choice. I use it in place of flour in most of my baking, sometimes in combination with Atkins bake mix, sometimes with protein powder or sometimes on it's own. It does have some fat in it as well when you read the nutritional content because of it's mixture of different flours and that, which I like because I use no oil or butter in my baking, choosing to substitute with apple sauce and Greek yogurt. I've made cakes, pancakes, waffles, breads, muffins, etc. with great success. The one thing though is it won't mix to a smooth consistency with basic mixing (only with a blender) because it does have flakes in it. This doesn't change the consistency of the final product however.
I hope this helps!