Fighting off those hunger pangs can be quite the battle – especially when we’re standing near the cookies this holiday season. So, we reason it’s simply a matter of willpower to fight the urge to eat everything in sight.
However, we now know that there’s a lot more that triggers hunger pangs than we think. And it’s not a matter of “good behavior,” as much as a delicate balance of calorie intake, neurons, and digestion hormones that decides to tell us when to eat.
For instance, a Medical News Today study shows that glial cells, found in the hypothalamus in the brain, respond to certain nutrients, and then “tell us” we’re full.
In addition, a separate study concludes that the hormone asprosin has the ability to both stimulate and suppress our appetites.
Now, J. Nicholas Betley and his team of researchers from the University of Pennsylvania have been delving deep into finding more about our gut and brain plays into our sensations of hunger pangs.
According to Betley, AgRP neurons exist in the hypothalamus and begin to activate when we get hungry. Think of them as a super-sensitive alarm clock.
Interestingly, the alarm gets “noisier” the hungrier you get, and then becomes “quieter” as soon as you can see and smell the food you’re about to eat.
Bentley’s quest was to learn more about AgRP neurons – specifically how they “turn off” after we sense food is near. So, his team began using in vivo calcium imaging to follow the neurons in the brains of mice and study their activity.
The mice received three meals at different times: regular chow (their normal meal from before the study), a zero-calorie strawberry gel (brand new to them) and the same gel, with calories (also unfamiliar to the mice).
Upon seeing the chow, the AgRP neurons in the mice’s brains immediately began to decrease. This is because they were familiar with the food, and already made the connection with the chow and being full.
The sight and smell of the zero-calorie gel, however, did not affect the AgRP neurons. Once the mice ate the gel, the neurons began to decrease, but only for a short time.
The researchers repeatedly gave the mice the gel, and this decrease in activity got smaller and smaller with each dose. This shows that the mice’s brains had made a link between the gel and low calorie intake.
However, when the strawberry gel with calories was given to the mice, a strange thing took place. According to Medical News Today:
Finally, when the same mice received the calorie-containing gel, AgRP neurons decreased in activity and continued to “lay low” for a long time.
“To solidify their findings, the team repeated the experiments in a reversed order — that is, starting with the calorie-containing gel — and used a different group of mice.
They also infused the gel straight into the rodents’ stomachs, and they found the same calorie-dependent effects.
Finally, infusions were repeated with pure sugars, fats, and proteins. The more calories the rodents received, the lower dropped the activity of AgRP neurons.
“[W]hat this study conclusively demonstrated,” says Betley, “is that nutrients are the primary regulators of this alarm system,” referring to AgRP neurons.
So what does this mean for us humans? By introducing nutrient-dense foods into our diet, and eating these as smaller meals throughout the day, this may help us maintain our healthy diet and avoid those nighttime binges after having been “good” all day.
