Don't use any of the old stuff. And I wouldn't trust any new stuff either.
To the OP: According to the success stoires, those first 50 pounds are pretty easy; it's the last 20 which are more difficult. If your husband has been Primal for 3-4 YEARS and made no progress at all, I don't think a tweak like IF-ing or gluten free beer is going to help. I agree with the recommendation of getting thoroughly tested by a specialist.