I keep this fact secret in my day to day life because it is way too close to the trendy gluten intolerance (I know people who legitly have crone's disease andthe like where if they eat a piece of bread they are hospitalized, they have a problem, but some fam/friends get 'run down' or have 'headaches' and that's BS). but...
I get absolutely wrecked if I eat too many simple carbs without enough protein. I don't know what the issue is exactly, but if I eat a pancake or a tiny brownie (which an amazing coworker brings in every monday), within 15 minutes I am so bloated my stomach is visibly distended, raging heartburn, and very painful cramps, these symptoms last several hours and start to fade as my body expels the horrendous unpleasantness brewing in my gut in various ways, the whole process takes 12 to 18 hours or so. I still experience it but it is significantly reduced if I eat a good amount of protein with it, like if I want pancakes/waffles/toast I need to eat at least an equal volume of eggs &/or meat with it. I love these things and still eat them if I don't have anything going on or just can't turn them down, and have gotten pretty good at hiding it.