A protein shake IS a protein meal. If you are going to eat in only 2 hours, a protein shake ought to hold you that long, especially if you can figure out how to add some fat to it. Use a could of tsps. of heavy cream or some oil like flax or borage (if you like the taste). It is the fats we eat that give us the feeling of fullness and satisfaction.

You can try drinking the shake and see how you feel when your next planned mealtime rolls around.