Simplified: It has been a beneficial way of our bodily system to work, in evolutionary ways of thinking.
Not So Simple
Hunger is an important mechanism in our survival.
Without it what would have driven our ancestors to go out and seek food they needed to survive?
Hunger is driven by, and also influences our endocrine system and our brain. You go hungry for too long your body will start preventing wasted energy. The result is a chemical signal to the brain that tells you to save energy and even get (mildly) depressed.
If this went on in an ever-increasing way, many of our ancestors wouldn’ve starved by just living of bodily reserves. Too weak and demotivated to go out and spend energy to gain food.
Our system needs a break from this negative incentive to work in a normal way.
How Does Your Body “Turn Off” Hunger?
It works AGAINST this mechanism with different hormones.
Fasting, as an example, is partially based on this. When you go hungry over longer times, your system will start releasing happiness-hormones!
The hungrier you get, the stronger the release.
At first, it’s only enough to make the hunger fade into the background. However, when you go hungry long enough, it is possible it’ll give you a kind of kick!
This system was evolutionarily beneficial, giving us a boost when we were at our lowest and hungriest. It ended up increasing our chances of long-term survival.
What About Eating Disorders?
Eating disorders like anorexia, bulemia, and addictive eating/binge eating/compulsive overeating offer many of the same effects.
In most eating disorders, it’s commonly the endocrine system releasing of happiness-hormones that drives the disorder.
Eating makes you happy, not eating makes you happy.
People who are severely over/underweight may have significant problems with depression, anxiety, and other possible problems because they rely solely on food and hunger to produce happiness-hormones.
