Caffeine and sugar intolerance?

Hi I am 25 yo and have ADHD. I am currently unmedicated. I have basically a pretty severe intolerance to sugar and caffeine. For example I just drank a poppi with only 50mg caffeine and I feel my heart pounding. I get really dizzy too. I barely drink liquids other than water (I am very hydrated I love water hahah) too. Sugar too, if I have two pieces of candy I’m out for like 24 hours, dizzy, exhausted, heart pounding. Why is this? Is this just because I don’t have a lot of sugar and caffeine in my daily life? Not that I need it but still