I picked up a book at Whole Earth Markets called "Allergy Free" by Konrad Kail, N.D. and they have a section with a sample rotation diet plan and a section on food allergy test types including ELISA.
My friend tested through a website called betterhealthUSA.com and she had similar success with weight reduction and found out she was allergic to bananas!
I've been debating on taking the test myself as it seems to work..
-T