I did not do the cleanse but went straight into the diet, as I’m a breastfeeding mother. I’ve been on the diet for about 3.5 months now and my symptoms are getting less every day – not quite symptom-free, but almost! So it is possible.
Re counting grams of sugar, I don’t bother. Life is too short to stress about that sort of thing. I just try to eat a good healthy range of allowed foods and I stay well away from anything that I know is going to cause a problem.