I'm not sugar free, but I can't have gluten, eggs, dairy, soy, peanuts, tree nuts, shellfish, sesame, mustard, coconut, ginger, artificial sweetners, raw fruits, and raw vegetables, plus a few other foods.
I've always eaten very very well at Disney even with QS. I do avoid all no Disney owned restaurants such as the world showcase and downtow Disney restaurants but the only Disney owned restaurant I have ever had a problem with was garden grill....the chef was not very good and something must have gotten cross contamination because that is the only reaction I have ever had at Disney.
Some of the best meals I had were:
Crystal palace
Liberty tree tavern
1900 park fare
Citricos
The Wave
50s prime time
Sci Fi dine in
The turf Club
QS meals:
Contempo cafe
Artists palette
Sunshine seasons
Cosmic rays
Columbia harbor house
POP century food court
All Star Sports food court
This last trip, we ordered food from garden grocer and I brought safe treats with me (cupcakes, cookies, brownies, etc) and I never touched any of the food from garden grocer. I was always so full after meals that I would have one safe treat at night but otherwise I was never hungry.