The state your body is probably in right now NO sugar is good sugar
Dr Gundry's high polyphenol diet recommendations is to cut out added sugar completly and avoid natural foods like dried fruit with high fructose content at least until you have lost weight and stabilized your digestive system.
The diet is all about getting the human gut back to the kind of foods it evolved to handle before crops became widely available thanks to the development of agriculture over the recent millenia - wheat & sugar cane not being in that category
Once you've got your digestive system and weight under control the occasional 'sweet treat' (or even some hard liquor) is not going to ruin everything.
Getting over the craving for sugar highs is THE BIG DEAL
Soon you will look at the miles of sugar and salt saturated processed food crap on supermarket shelves and ask yourself why people pay their hard earned money to kill themselves
Sugar is not entirely bad if its taken in recommended amount. Removing sugar and agricultural food containing starch entirely from diet will eventually kill you due to lack of glucose which is your body fuel. Goal of taking starch or any kind of sugar whether its sucrose or fructose, is providing glucose to body for energy production. Carbohydrates are essential part of your diet. You can not entirely eliminate them.