Overeating Is Hardwired in the Brain: Study
Thu, October 21, 2021

Overeating Is Hardwired in the Brain: Study

Acting without thinking can lead to dire consequences although not all the time. It can be a one-time thing when you momentarily lost control. One of the most common acts of impulsivity is binge eating / Photo by: lightfieldstudios via 123RF

 

Acting without thinking can lead to dire consequences although not all the time. It can be a one-time thing when you momentarily lost control. One of the most common acts of impulsivity is binge eating.

While it may seem like an innocent slip-up, being able to consume too much food all the time could lead to adverse effects. You can't be blamed for this, though, considering that humans are programmed to not say no to impulsive eating, according to a new study.


Brain Circuits and Food Impulsivity

Researchers have identified a specific brain circuit that affects food impulsivity in a study published in the journal Nature Communications. The study used a rat model to show that a type of transmitter in the hypothalamus—called melanin-concentrating hormone (MCH)—plays a role in impulsive behavior.

Experimental models like this are used to activate a certain circuitry in the brain to get a specific behavioral response.

In their impulsivity test, the scientists trained rats to press a lever to receive a "delicious, high-fat, high-sugar" pellet. The rats wait 20 seconds to press the lever again because pressing too soon would result in them needing to wait for another 20 seconds.

Advanced techniques were then used to stimulate a specific MCH neural pathway from the hypothalamus to the hippocampus, the brain region responsible for learning and memory function.

Analysis of the experiment showed that MCH doesn't affect the animals' liking for food or their effort to receive food. Instead, the circuit acted on the animals' inhibitory control (their ability to control themselves from trying to get the food).

"There's underlying physiology in your brain that is regulating your capacity to say no to [impulsive eating]," Emily Noble, the lead author of the study from the University of Georgia College of Family and Consumer, said in a press release. "We found that when we activate the cells in the brain that produce MCH, animals become more impulsive in their behavior around food."

She noted that activating that MCH pathway heightened the impulsive behavior for "caloric need or motivation to consume delicious food" without affecting normal eating habits.

The lead author said understanding this brain circuit, which specifically affects food impulsivity, "opens the door to the possibility that one day we might be able to develop therapeutics for overeating that help people stick to a diet without reducing normal appetite or making delicious foods less delicious."

Overeating and Obesity

Developing treatments based on the study is crucial, especially now that about 2.1 billion people worldwide are obese. That number is expected to rise after rates have tripled since 1975.

Overeating is seen as the primary cause of obesity alongside poor physical activity, according to another study that looked into the conventional notion that a sedentary lifestyle attributes to the condition.

The research, published in the journal Science Advances, compared the health data of children from the Shuar community in the Amazon forest to industrialized children in the US and the UK.

Results showed that children from the three countries burn the same amount of calories—this despite Amazonian children being more physically active (25%) than their industrialized counterparts.

These children also have 20% greater resting energy expenditure than those living in the cities, evident in the elevated activity in their immune system, as per the English daily newspaper Deccan Herald.

"This similarity in energy expenditure suggests that the human body can flexibly balance energy budgets in different contexts," said Samuel Urlacher, a co-author of the study from Baylor University. He added that the main cause of long-term weight gain and the shift in global nutrition, which usually begins in childhood, is eating too much and not getting ample exercise. 

Co-author Herman Pontzer from Duke University said their findings also support earlier research done among adults and show that "energy expenditure is also constrained during childhood."

Developing treatments based on the study is crucial, especially now that about 2.1 billion people worldwide are obese. That number is expected to rise after rates have tripled since 1975 / Photo by: belchonock via 123RF


Overeating Vs. Binge Eating

Another issue that arises with overeating is its potential to elevate to binge-eating disorder. Overeating is usually an occasional habit, which may turn into unhealthy binging if it becomes more frequent.

In 2015, an estimated 2.8 million people in the US have binge eating disorder (BED), making it the most common disorder in the country. BED is most common among women, affecting 3.5% of the female population compared to 2% of men and 1.6% of teens, according to the data from medical news site Healthline.

There is a very thin line between overeating and BED that is often blurred. According to Verywell Mind, a trusted and compassionate online resource that provides the guidance people need to improve their mental health and find balance, a key difference between the two conditions is how they feel after overeating or binging.

"A sense of disgust does not make a binge eater stop eating," the resource said. "An overeater will likely listen to that voice and stop eating."

Generally, binge eaters are likely to eat more often compared to people who tend to overeat. They also consume food more rapidly and feel that they have lost control when eating.

However, Verywell Mind noted that continuous snacking through the day—a habit that is known as grazing—is not considered as binge eating.

This only proves that you really can’t have too much of everything, even if they are good.