I keep having to look this information up, so I decided to write a blog post.
Trainer Jorge Cruise, recommends these, healthier, low carbohydrate alternative flours for these purposes:
Coconut Flour — breading meats for frying or faux frying
Almond Flour — cake baking — Swap out ratio: 1 to 1
Flax Meal/Flour — pancakes, waffles, cookies and muffins — Swap out ratio: “you can replace up to 1/4 of it” — I believe this means that if a standard recipe calls for 1 cup of regular flour, you use 3/4 cup of the regular flour plus 1/4 cup of milled flax seed, for example.
Also of note, per this flax seed website, you can substitute milled flax seed for eggs and butter/oil in the following amounts:
EGGS: 1 Tbsp of ground Omega Golden Flax Seed plus 3 Tbsp water = 1 egg. Substitute a 1:3 ratio of ground flax seed and water mixture for each egg in recipes for pancakes, muffins and cookies. Allow to sit for several minutes together before adding to your recipe.
BUTTER / OIL: 3 Tbsp ground Omega Golden Flax Seed = 1 Tbsp margarine, butter or cooking oil. Substitute for all or some of the fat depending on the recipe. To substitute for all of the fat, increase liquid by 75% as ground flax absorbs liquid. Baked goods brown more quickly.
Some additional info.