Unfortunately, I don't. I tried many different diets, but they either didn't work, or weren't sustainable. I settled on two rules, lost 50+ lbs, and have been able to sustain it for a few years now. My rules are (1) don't overeat, and (2) don't eat processed foods.
It took a few months before I figured out what my portions were, since I don't feel full until about 15-20 minutes after I am. By the time I knew how much I needed to eat in one sitting, I'd become used to eating that amount, so it was a breeze.
I do eat whatever I want, with the exception of processed foods. If I can't make it at home with whole ingredients, I'll likely not eat it. I do cheat every so often, but not much, and not a large amount (I love a box of Raisinettes during a movie.)
As for not being able to think straight after lunch, I used to get that way when I'd eat too much. I used to love feeling full, but it would definitely affect brain function. Now, I get ill when I overeat. I also try to eat a high protein, high fiber breakfast, because it seems to get me further through the day than anything else (I eat a small late lunch).