Preheat a waffle iron, and coat with cooking spray.
In a medium bowl, stir together the whole wheat flour, cornmeal, sugar, baking powder and baking soda. Make a well in the center, and stir in the buttermilk just until smooth. In a separate bowl, whip egg whites with an electric mixer until thick enough to hold a soft peak. Carefully fold the egg whites into the batter.
Spoon batter onto the hot waffle iron in an amount appropriate for your iron. Close, and cook until the iron stops steaming, and the waffles are golden brown.