The theory of blood pH. How does this theory work?

I saw a book by Dr. Robert Young today in the bookstore. The book basically says if you are overweight it is because you are too acid, and that you need to alkalize. Is this quackery, or does it have some truth to it. Please give some references if you have any.

Quack, quack, quack.

If it quacks like a duck . . .