All of these issues respond--often dramatically--to elimination of wheat and cornstarch.
Why would there be undesirable effects of eliminating wheat?
One clear issue is that elimination of wheat and other sugar-equivalents deprives your body of glucose. Your body then needs to resort to fatty acid metabolism to generate energy. Apparently, some people are inefficient at this conversion, having subsisted on carbohydrates for the last few decades of their lives. However, as fatty acid metabolism kicks in, energy generation improves. That is my (over-)simplified way of reasoning it through.
However, are there other explanations behind the mental fogginess, drop in energy, and overwhelming sleepiness? Some readers of this blog have suggested that, since opioid-like sequences (i.e., amino acide sequences that activate opiate receptors) are present in wheat, perhaps withdrawal from wheat represents a lesser form of opiate withdrawal. I find this a fascinating possibility, though I know of no literature devoted to establishing a cause-effect relationship.
Whatever the mechanism, I find it very peculiar that this food widely touted by the USDA, American Heart Association, and other agencies actually triggers a withdrawal syndrome in approximately 25% of people. Spinach does not trigger withdrawal. Nor does flaxseed, olive oil, almonds, and countless other healthy foods.
Then why would whole wheat grains be lumped with other healthy foods?