You want evidence that the quality of food you eat affects how you feel and the quality of your brain activity?
Unless you're starving, your brain pretty much only runs only on glucose. That means that whatever you eat, good/bad fresh/packaged, whatever, just gets converted to glucose.
Assuming you're getting basic levels of required vitamins, I don't see any reason why one diet would be beneficial over another in terms of brain performance.
That's "reduced brain effectiveness" too.
No, you're making the claim you should already have more evidence to back it up than a snark.
it boggles the mind.
as it turns out, happy meals are, in fact, a great replacement for breast milk.
That's sort of beside the point though. I'm just tired of the ridiculous amount of misinformation in the diet, nutrition, and exercise fields. It's not like there isn't a long history of claims that are "just common sense" turning out completely wrong ("eating fat makes you fat", "eating high cholesterol food gives you high cholesterol" (mostly genetics), "diet and exercise are equally important to losing weight" (reality is that it's mostly diet), etc.)
Bottom line, if you're going to make a claim that certain food improve your brain's performance, you should have just a shred of evidence.
This doesn't even include the fact that some things in food directly affect the brain, such as caffeine.
When you eat fats, proteins and slower-digesting carbs the glucose regulation problem doesn't occur, at least not on the same scale, so your brain and body can perform undistributed for potentially many, many hours. Consequently the only problems come from nutritional content and digestive efficiency.
For elite endurance athletes there is still reason to "carb up" to pump as much glyogen into the muscles as possible, but that isn't most of us, and it isn't something you need for brain work.
I grew up eating nothing but TV dinners and ramen, in college I added pizza and fast food to the mix. Since I've gotten married I eat regular healthy meals. Anecdotally, I don't notice any difference in my brain function, but I do weigh 40 pounds more then college :)