After a cheat or even eating the Artificial Sweeteners or bread substitutes, I find that I get incredible pain and major bowel problems. It is because our body isn't used to it anymore (or you may have developed an allergy)
It is just another incentive not to cheat, huh? (albeit a cruel one!)
(But now I can't have ANY sweets, even 'legal" ones) Too bad for me! Dommage!