I would stay away from soy. Though soy does have many healthy benefits, it has also been linked to Alzheimer's in men and reproductive tumors in women and many other ill effects. There are other things you can get those health benefits from without getting the ill effects.
I would use a high quality organic Protein Shake. I have an Isagenix protein shake for Breakfast every morning. I like the chocolate ones the best, but the vanilla is good too. I prefer the chocolate because it is rich and tastes really good. I am pretty lucky, I have read a lot about how nasty protein shakes can taste, but this one was recommended by my massage therapist.
If you want to know more about soy and don't want to take my word for it, read this.