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The slogan for Pringles, "once you pop, you can’t stop," may be true, and not just because they are delicious. Scientists have found that something in our brains makes us indulge in food as well as drugs and alcohol.
Scientists from the University of Michigan decided to study a part of the brain called the neostriatum that may be involved in providing reward signals when we engage in pleasurable tasks.
The main player in this brain area is enkephalin, a chemical that turns up brain activity. It was discovered in 1975, and is known as a painkiller and a possible neurotransmitter. Enkephalin is produced in the brain and binds to the same receptors as many anesthetic and psychoactive drugs.
To find out how enkephalin acts in the brain, the researchers offered rats an unlimited amount of M&M’s. The average rat ate 10 candies in 20 minutes, which is a lot of candy for their small size.
Researchers found that levels of enkephalin spiked in the neostriatum, and the rats that ate the most M&M’s had the quickest and highest spike of enkephalin.
The spike in enkephalin could have been a result or the cause of the binge eating. To figure this out, the experiment was repeated, but this time the researchers injected the rats' brains with enkephalin. With the extra brain stimulants, the rats ate twice as much candy — so the chemical seems to be the cause of the overeating, not the result of it.
It could be that the rats overeat because enkephalin makes food taste better. Although it may sound ridiculous, the researchers watched the rats’ facial expressions to see how happy the were during the binge. The more they lick their lips and stick out their tongues, the tastier the food.
But, the dosed rats didn't show this.
Lead author, Alexandra DiFeliceantonio of the University o Michigan, tells Smithsonian.com's Surprising Science blog “that the brain has more extensive systems to make individuals want to over-consume rewards than previously thought.”
She concluded: “It may be one reason why over-consumption is a problem today.”
Just remember: Once you pop, try to stop before you eat the entire can.
