When Jenni* started using a medication called liraglutide to lose weight, she noticed changes not just in her appetite but also in how she thought about food.
Previously, the smell of hot chips in a deep fryer would elicit a deep craving for the crunchy, salty snack. However, once on the medication, she suddenly had zero interest in them. Her cravings for food disappeared almost entirely.
“All of that was just blanked out, completely cancelled, which was so great,” Jenni said.
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Liraglutide is part of a class of drugs known as GLP-1 receptor agonists, which includes tirzepatide (brand name Mounjaro) and semaglutide (sold as Ozempic and Wegovy). These medications have been widely used to manage blood sugar levels in people with type 2 diabetes, but they are now being recognized for their profound effects on weight loss and appetite suppression.
The Science Behind GLP-1 Receptor Agonists
GLP-1 agonists (also called GLP-1 receptor agonists or GLP-1 analogues) are medications that mimic a natural hormone called glucagon-like peptide 1 (GLP-1). This hormone plays a key role in regulating blood sugar levels by stimulating insulin secretion in the pancreas, which helps shuttle sugar from the blood into the body’s cells.
In the early 1900s, scientists theorized that directly administering GLP-1 could help control diabetes. However, because the hormone breaks down in the body within minutes, it was not effective for long-term treatment.
A breakthrough came in the 1980s when researchers discovered a molecule similar to GLP-1 in the saliva of the venomous Gila monster (Heloderma suspectum). This molecule, unlike natural GLP-1, did not break down as quickly and was able to lower blood sugar levels in both mice and people with type 2 diabetes for extended periods.
This discovery led to the development of exenatide, the first GLP-1 agonist approved by the US Food and Drug Administration (FDA) in 2005. Pharmaceutical companies have since developed more advanced versions of GLP-1 agonists, including liraglutide and semaglutide, which have longer-lasting effects and can be administered through weekly injections.
How GLP-1 Agonists Influence the Brain
Aside from regulating blood sugar, GLP-1 agonists also slow down the movement of food through the digestive system. This process extends the feeling of fullness after eating, reducing overall calorie intake.
“There are stretch receptors in your stomach that tell your brain how full you are and how much of a meal you’ve had,” says Lotus Jeffs, a researcher studying anti-obesity medications and the brain at Monash University. “The longer that food sits in the stomach, the longer these signals are sent to the brain, making you feel full for a longer period.”
Additionally, GLP-1 agonists have direct effects on the brain itself. The drugs can penetrate the blood-brain barrier and act on the hindbrain, which regulates appetite and satiety. This area of the brain also plays a role in nausea, which explains why some people experience nausea as a side effect of the medication.
Common side effects of GLP-1 agonists include:
- Nausea
- Headache
- Constipation
- Diarrhea
Studies have shown that GLP-1 agonists can alter brain pathways involved in cravings, reducing desires for sweets and high-fat foods. This phenomenon, often called “food noise,” describes the constant, intrusive thoughts about food that many people struggle with, especially those trying to lose weight.
Beyond Weight Loss: Impact on Other Addictions
Interestingly, GLP-1 agonists may also help curb cravings for substances beyond food, including alcohol, drugs, and even gambling.
Recent research in animals suggests that GLP-1 agonists can reduce cravings for addictive substances by affecting brain circuits associated with reward and pleasure. Some human studies have yielded promising results as well.
A recent study published in JAMA Psychiatry examined the effects of semaglutide on people with alcohol use disorder. Participants were given a low dose of the drug each week for nine weeks. Researchers found that those taking semaglutide experienced fewer cravings for alcohol compared to those in the placebo group. They also drank less on the days they did consume alcohol.
Additionally, some participants who smoked cigarettes reported that they smoked less frequently while on the medication.
However, not all studies have confirmed these findings. A 2022 Danish study using exenatide found no significant reduction in alcohol cravings or drinking behavior. However, researchers noted that people with both obesity and alcohol use disorder tended to drink less over the course of the 26-week study.
“So it looks like there is potential for these drugs to be used for alcohol use disorder,” says Ms. Jeffs. “However, our understanding of what’s driving this effect is still quite limited.”
Challenges and Future Directions
Despite their effectiveness, GLP-1 agonists come with challenges. One major issue is cost. These drugs can be expensive, costing hundreds of dollars per month, and to maintain weight loss, patients typically need to stay on the medication long-term.
Additionally, while these drugs suppress appetite and reduce cravings, they do not address the underlying lifestyle and behavioral factors that contribute to obesity and addiction. Healthcare professionals emphasize that GLP-1 agonists should be used as part of a broader treatment plan, including dietary changes, exercise, and psychological support.
There are also concerns about the long-term effects of these medications. Since they are relatively new in the field of weight management, researchers are still studying their long-term safety and effectiveness.
The Future of GLP-1 Agonists
The success of GLP-1 agonists has spurred interest in developing even more advanced medications for weight loss and addiction treatment. Scientists are now exploring combination therapies that target multiple hormonal pathways simultaneously, potentially leading to even greater appetite suppression and metabolic benefits.
Meanwhile, pharmaceutical companies are working on new GLP-1 agonists that can be taken orally, rather than through injections, making them more accessible to a broader population.
As more research emerges, the potential uses for GLP-1 agonists continue to expand beyond diabetes and obesity. Their impact on addiction-related cravings could open new doors for treating conditions such as alcohol use disorder, smoking cessation, and even compulsive behaviors like gambling.
Conclusion
GLP-1 receptor agonists, including Ozempic, Wegovy, and Mounjaro, have revolutionized the treatment of obesity and type 2 diabetes. Their ability to suppress appetite, reduce food cravings, and even impact addictive behaviors has made them a game-changer in medical science.
While challenges remain, including cost and long-term safety concerns, the growing body of research suggests that these medications have the potential to transform the way we approach weight loss and addiction treatment. As scientists continue to unravel their full effects on the brain and metabolism, the future of GLP-1 agonists appears bright.
