I had work done on me, so I'm not great at digesting carbs anymore, and I think my brain notices. If I try to have carbs without much protein or fat for breakfast, I get hungry again very quickly, even if the carbs are healthy and high-fibre. My digestive system is essentially tuned more toward keto or paleo now. But it would get a little monotonous to *just* eat that all the time. It's not varied enough. It would also make me a very annoying guest to have at a restaurant or a party. I eat grain-based breakfasts out of old habit. It's a reassuring feeling when things are as they always were.