Your Brain on GLP-1: How It Rewires Appetite and Reduces Food Cravings
“All of the food noise just disappeared,” is a phrase we hear all the time from patients, even after just a few short weeks on tirzepatide.
This statement has been repeated by patients since we started treating them in 2021.
Medical professionals and researchers alike have known that GLP-1 medications reduce appetite thanks to the stimulation of insulin production and the slowing of stomach emptying, but these mechanisms have little to do with the cognitive piece of the puzzle.
In fact, most diet interventions with reduced caloric intake actually intensify feelings of craving that make those highly satisfying, high fat, high salt, and high sugar foods all the more tempting.
So what is different about GLP-1s that this mental chatter simply fades away?
Researchers hoped to answer this question in a new study published in Nature Medicine.
To put it plainly, when researchers scanned the brains of 114 patients on tirzepatide and a placebo in response to visual food cues and triggers, the tirzepatide users’ brains were noticeably quiet.
Let’s talk about it!
Why Study GLP-1s?
GLP-1s were introduced to the market as a medication that could help diabetes patients to stimulate insulin production and manage their disease.
Doctors, patients, and researchers alike soon realized that it had a powerful side effect— weight loss.
Effective weight management helps not only diabetes patients to stay healthy, but also helps overweight and obese people to gain control of their health and prevent weight related chronic illnesses like high blood pressure, high cholesterol, cardiovascular disease, and more.
It’s not a question of whether or not they are effective, with 89% of patients using tirzepatide losing at least 5% of their body weight while taking the medication.
The statistics show that GLP-1s such as tirzepatide are highly effective, but appetite suppression alone doesn’t seem to answer the question of where this food noise is going.
In this study, researchers attempted to answer this question through brain scans.
114 participants were randomized with 37 receiving tirzepatide, 38 receiving liraglutide, and 39 receiving a placebo over a short-term 6-week period. They examined patients to study behaviors around food, total calories consumed, and how the patients’ brains responded to food cues.
What Did the Research Show?
Researchers broke down how patients responded to tirzepatide, liraglutide, and the placebo by looking at how much the patient actually ate and how much weight they lost, how they self reported their appetite and cravings, and how their brains responded to food cues.
Let’s break down the results.
1. Caloric intake & Weight Loss
Researchers found that patients on tirzepatide ate fewer calories and lost more weigh than those on the placebo.
Specifically, tirzepatide reduced lunchtime intake by 523 calories at week 3 which was sustained at week 6 of the trial. In 6 weeks, patients on tirzepatide lost an average of 15 pounds compared to placebo patients who lost just 1.3 pounds on average.
This is consistent with our understanding of tirzepatide as a powerful appetite suppressant, but where things get interesting is how patients reported their appetite and cravings as well as what the brain activity shows.
2. Appetite and Cravings
Have you ever tried to go on a calorie deficit? For most people, when they consume fewer calories, they experience a higher amount of food noise including increased cravings for things like sweets, fast food, and high fat foods.
Despite eating over 500 calories less per meal, patients on tirzepatide also saw a reduction in these cravings. They reported both reduced cravings for sweets and fast food as well as increased fullness and satiety.
What’s more is that researchers observed less impulsive behaviors and disinhibition around food, or the tendency for emotional eating or eating not because of hunger but due to environmental triggers. All of these behaviors reduced significantly.
3. Brain Activity
Perhaps the most interesting part of the study and one we are still trying to understand fully, is how tirzepatide impacts the hunger centers of the brain.
Researchers saw a significant decrease in activity in four brain regions closely associated with appetite and the feeling of reward from food including the orbitofrontal cortex, the medial frontal gyrus, the hippocampus, and the cingulate gyrus.
Now, we don’t expect the everyday person to know what exactly these regions of the brains do when it comes to food, so just understand that these regions control food reward, appetite, emotional memory, and impulse control.
In other words, they influence how the brain responds to food and forms habits around food.
In the study, the patients on tirzepatide, liraglutide, and the placebo were presented with food triggers that normally light up these regions of the brain, like images of your favorite high-fat, high-sugar foods.
Instead of lighting up, these regions stayed quiet for patients on tirzepatide compared to the placebo group.
Every Study Has Limitations
Keep in mind that this research is new and warrants further study to understand fully.
Some of the limitations of this particular study were its short duration, just 6 weeks, leaving us wondering how tirzepatide impacts the brain over prolonged use. There was also a reported imbalance in sex distribution in the study groups, with fewer women being sorted into the liraglutide group.
Also keep in mind that this study was funded by Eli Lily, the maker of brand name tirzepatide medication, Mounjaro.
Despite these limitations, the research does seem promising, especially because it mirrors the results of another line of study, addiction research, which suggests that GLP-1’s impact on the brain could help addicts reduce cravings for everything from cigarettes to alcohol.
What’s the Takeaway?
Food noise is one of the biggest complaints from weight loss patients who are struggling to stay in a calorie deficit despite their best efforts.
We know that hunger is more than just the physical need for food. There are environmental and emotional triggers that often override our body’s natural cues. When you start cutting calories, these triggers tend to get louder.
GLP-1s have a significant impact on not just the physical feelings of satiety, but on that relentless chatter that exists in your mind when you are trying to develop better habits around food.
The research is new, but promising, and indicates that GLP-1’s actually do have an impact on how the brain is responding to those food triggers in the real world.
What does a world with less food noise look like?
A healthier, more confident you!
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