If you’ve ever continued eating long after you’re full, then researchers at the University of Michigan think they know why.
The human brain’s drive to continue eating is more powerful than the urge to stop when you’re full, according to a new study from the university’s Molecular and Behavioral Neuroscience Institute.
Published in the journal Proceedings of the National Academy of Science, the study looked at how “two tiny clusters of cells battle for control of feeding behavior.”
“The one that drives eating overpowers the one that says to stop,” Michigan University’s Kara Gavin explained.
Specifically, the researchers honed in on the cell groups POMC and AgRP. These two groups are located side by side in the brain and compete to regulate appetite.
“In general, POMC acts like a brake on feeding when it gets certain signals from the body, and AgRP acts like an accelerator pedal, especially when food is scarce or it’s been some time since a meal.”
This means AgRP is the brain’s “go” button, while POMC is a “stop” sign that should make you want to stop eating.
In rodent tests, the researchers tried activating these two groups of brain cells separately but quickly encountered a problem. Each time they tried to activate the POMC cells, AgRP cells would light up.
“In other words, they had turned on both the brake and the gas pedal for eating,” Gavin explained.
Once activated, the two groups of brain cells would send contradictory signals, but the AgRP would easily overpower the POMC. As the researchers discovered, this was because the “go” signal was linked to the brain’s opioid system. This explained why the urge to keep eating was so much stronger than the urge to stop, though it also gave the researchers a clue as to how to manage this problem.
“When we administered naloxone, which blocks opioid receptors, the feeding behavior stopped,” said lead researcher Huda Akil, Ph.D.
Naloxone is usually used to block the effects of opioid drugs like heroin and is routinely given to overdose sufferers. However, when given to the hungry test rodents, naloxone appeared to weaken AgRP’s signals urging them to keep eating.
The findings could mark a breakthrough in the world’s battle with obesity. Around 93.3 million of U.S. adults are considered obese, according to the Centers for Disease Control and Prevention. By the middle of the century, obesity could overtake smoking as the biggest cause of cancer for women, the BBC reported last week.
While the latest study may have provided an important clue into how to reduce overeating, the researchers themselves conceded the world’s obesity problem is about more than just competing brain signals.
“There’s a whole industry built on enticing you to eat, whether you need it or not, through visual cues, packaging, smells, emotional associations,” Akil said.
New research suggests obesity could overtake smoking as the biggest preventable cause of cancer in women in the next 25 years. Our Cancer Policy Research Centre has found that more people need to be made aware of the link between obesity and cancer: https://t.co/kBxk0uIWEm pic.twitter.com/too69tWFBL— CRUK Policy (@CRUK_Policy) September 25, 2018