I will put this in the Category of a "myth buster". I recommend taking supplements prior to working out and so this is support for that recommendation. That said, I know many folks think that exercising on an empty stomach is good for weight loss. Turns out, through the data,to be a wrong assumption.
http://well.blogs.nytimes.com/2011/06/27/does-exercising-on-an-empty-stomach-burn-more-fat/