When I did the veg thing, I used soy for much of my food. I think soy milk is the real problem. I was drinking it down all the time and I ended up having severe mestural problems and I just never got enough protein.

I think some soy products ( if not all) play with hormones. Well that's my belief.

A lot of research has shown that unfermented Soy is not good, and that only fermented soy is healthy.
And fermented soy does not taste too well. And its otherwise very difficult for a vegan/vegetarian to get enough proper protein.

Tempeh is a delicious and and very satisfying form of fermented soy. Vegetarians who also include eggs and dairy in their diets have a variety of good proteins available. It's also possible to do a Vegan form of the Zone.

I have been a vegetarian my whole life. I never think about getting proteins its how you eat. Most people who convert try one of two things.
Junk food vegetarian or straight vegetable and fruit (very hard). I have not had alot of soy milk. I prefer almond milk.