Keep with it. I hit a 6 week plateau and am just now moving again.
Make sure you are following the men's plan and getting enough calories. As I found out last week...that was why I was in a 6 week plateau...I was not getting enough once I threw in exercise.
Averages are averages....that means you may have weeks were you lose nothing followed by weeks where you are losing insane amounts, but once you do the math, it averages out to whatever amount.
Take into consideration things like, age, starting weight, your body's actual metabolism, and so on.
If soy is a problem, look into alternatives, such as those found on diet direct....a lot of their products do not contain soy at all and many IPers have found them to be reasonable substitutes.
But stick with it. It does work. It helps to remember you did not put it on over night, it will not come off over night. It also helps to remember that the average person gains 10-15 pounds a year but usually looses 1-2 pounds a week...or 52-104 pounds a year...and you have *averaged* more than that to date
Oh---and a lot of people don't see any movement week two or sometimes week three. I've found that is usually people who had substantial loses on week one.