If you have gut inflammation or leaky gut, sugars, starches, or carbs can cause symptoms. The gut and brain are very closely connected. That's why we get brain fog from something our gut doesn't like. Are you familiar with the SCD diet? There's a lot of information on their site about this stuff and food recommendations. Even if you're not on the diet, it's helpful reading. You may know about it already but if not here's a link:
I'm assuming that if one has Celiac, then by definition they are dealing with intestinal permeability unless they got their number down to zero. But why would carbs cause problems for my brain when fat and/or protein would not? What's the reasoning or cause behind that? I have read about the specific carbohydrate diet before but I'm rusty so I'll read up on it.