In a medium size bowl, beat egg whites, eggs, yogurt and water until blended. Using a nonstick pan, melt butter. Add eggs and scramble, stirring often. Cook until you reach desired consistency.
Divide eggs among 2 plates. Top each serving with 1 tablespoon cheese. Add a little salt and pepper, as desired.
To make a really complete, satisfying meal, serve eggs with sliced tomatoes and a cup of fresh fruit. Add a slice of multigrain or whole-wheat toast, if desired.