When using heavy flour (see below for examples) or gluten free replacements adding air to the mixture is necessary to get a lighter and fluffier product.
Baking soda – sodium bicarbonate
When mixed with an acid like vinegar or lemon juice it produces a rapid exothermic reaction which quickly causes oxygen to be produced, putting air into the mixture, holding up the heavy flour.
Are just a few of the healthy grains used in healthy baking they are all heavier than regular All Purpose flours.
When baking with these healthy alternatives. It is important to get as much air into the batter to achieve fluffiness.