There is a hormone called ghrelin that is produced in the lining of the stomach when it is empty. This hormone travels through the blood into the brain, where it triggers receptors in the hypothalamus to make you feel hungry.
If you feel hungry, it is a good bet that there is ghrelin getting to your brain.
The hormone has that funny name because it regulates the release of growth hormone. (Growth Hormone RELease, folowed by the “in” suffix used for hormones.)
While the benefits of human growth hormone are well known to athletes and geriatricians, the effects of ghrelin in the brain are what I am interested in at the moment, because they seem to reach beyond the appetite stimulus, and affect learning and memory.
I go on a low calorie diet every February, and one of the things I have noticed during those periods (beside feeling hungry all the time) is that I seem to be more alert, and paradoxically feel like I am full of energy. It now seems that these mental benefits are more than just delusions of a starving brain.
Now, there also seems to be evidence that hunger might also increase anxiety and aggression, although I have not noticed those effects while on my diet. But if you do, there is a quick cure in the refrigerator.
Just don’t eat yourself stupid.