Stevia impact on gut

I am doing a 2 week fast. I take vitamins and minerals. Maintaining electrolytes when it’s hot out is difficult. I bought Dr. Bergs electrolyte powder. It’s carbohydrate/sugar free with no fiber. An important part of the fast for me is the gut biome reset when you get rid of the carbohydrate craving gut bacteria/biome. That’s why I don’t take fiber during my fast. I read stevia can cause gut biome growth. I need 2 starve on gut to reset it. What does citric acid do to the gut?