exception eats and health issues

I understand the purpose of scheduled exception eats, and how it is important for it to contain flour or sugar, to continue to trigger urges so that those urges continue to bring to light underlying emotions.
I have liver disease such that my doctor has me on a diet that is devoid of flour and sugar, to help my liver to heal. Would exception eats be as effective if they aren’t a formerly craved food? Or is it okay to include flour or sugar, for this one exception, since it is only once a week?
Thank you!