Feeling good is measured mostly by how I feel a few hours after I've eaten, but what I eat can affect me for up to a few days.
The "do eat" list is fish, meat, eggs, fruit, veggies, seafood (except crayfish and squid), nuts, seeds, sweet potato, squash, probably mushrooms, probably tofu, beans, olive oil (haven't experimented with other oils), and salt, herbs, and spices. The "don't eat" list is sugar, honey, dairy, and grains (including corn). And jicama. Lentils are marginal. Quinoa is probably ok, but I haven't tested it enough to be sure. I haven't done a careful check on wild rice, either.
Sugar knocks me out. A very moderate binge (a box of Entemann's chocolate covered donuts--that's 8 fairly large donuts) eaten in the course of two or three days means I won't get anything much done for two or three days afterwards. What's worse, it looks like an emotional problem--I keep thinking "I don't care", which is not what you'd call a standard symptom of being poisoned. I have tested this out enough times to be quite sure of it.
If I complain about not getting anything done, I would be pathetically grateful if you'd ask me what I've been eating lately.
Cow's milk (yes, even reasonably hard cheeses) upsets my stomach if I eat much of it. Goat's milk cheese is easier on my stomach, but both sorts of cheese seem to lower my mood. There's more to milk than lactose, and some people have trouble with the non-lactose components.
Grains also seem to do some mood/energy lowering for me, and wheat is apt to make me obsess about things that get on my nerves.
I've been poking around this for some time, but I had no idea how much better I'd feel if I gave up sugar and grain and dairy at the same time.
Quality matters. Fortunately, I can get very good grass fed beef at the farmer's market for about $7/pound for roasts, and frozen fish at Trader Joe's for $5 to $7/pound. I can eat just about any amount of the $3+/dozen free range/organic eggs, but a couple of days in a row of $1/dozen eggs make me feel a little off.
I haven't tried high omega-3 eggs--I've heard that they don't have much added omega-3, and I'm supplementing with fish oil anyway.
Veggies are important. I've tried making meals of one of those Indian meal packets plus eggs, and I feel a lot better if some veggies are added to the stirfry.
I loosen up a lot on the requirements if I'm eating out, but I'm eating out a lot less. Even a cheap meal out costs at least $7, and I can eat much better for less at home. Also, since the foods that are good for me are very low glycemic, I don't feel hungry as often, and when I do feel hungry, it doesn't feel as bad.
I've lost a little weight, but am trying to keep a firm grip on the idea that losing weight doesn't prove anything about whether I'm doing something right.
The goal is to have more good hours.
When I first started with this, I wondered why more people aren't doing this simple experiment, but then I realized that it takes pretty steady self-monitoring (though a diary could substitute if you don't do it as habitually as I do) and eating a wide enough variety of foods to have some idea of their effects.
And then you get an answer, and it's good news in a way and a pain in the ass in others. Notice that most culturally elaborated fun foods are off my list. I guess I could devil some eggs. Seriously, if any of you have ideas about interesting things to do with the foods on my "do eat" list, let me know. There's nothing wrong with living on stirfries and three sisters soup, but I could use a little more variety. (Three sisters soup includes corn, but it seems to be little enough to not matter.)