The brain of each animal is preloaded with certain rules for behavior, and when it comes across an exaggerated version of that rule, it lights up like a Christmas tree.
Scientists refer to these exaggerated cues as supernormal stimuli. A supernormal stimulus is a heightened version of reality, and it elicits a stronger response than usual.
Junk food, for example, drives our reward systems into a frenzy. After spending hundreds of thousands of years hunting and foraging for food in the wild, the human brain has evolved to place a high value on salt, sugar, and fat.
Such foods are often calorie-dense and they were quite rare when our ancient ancestors were roaming the savannah. When you don’t know where your next meal is coming from, eating as much as possible is an excellent strategy for survival.
Today, however, we live in a calorie-rich environment. Food is abundant, but your brain continues to crave it like it is scarce.
Placing a high value on salt, sugar, and fat is no longer advantageous to our health, but the craving persists because the brain’s reward centers have not changed for approximately fifty thousand years. The modern food industry relies on stretching our Paleolithic instincts beyond their evolutionary purpose.
Companies spend millions of dollars to discover the most satisfying level of crunch in a potato chip or the perfect amount of fizz in a soda.
With natural, unprocessed foods, you tend to experience the same sensations over and over—how’s that seventeenth bite of kale taste? After a few minutes, your brain loses interest and you begin to feel full.
The result, of course, is that you overeat because hyperpalatable foods are more attractive to the human brain. As Stephan Guyenet, a neuroscientist who specializes in eating behavior and obesity, says, “We’ve gotten too good at pushing our own buttons.”