Researchers studying brain activity in patients with significant overeating issues found that Eli Lilly’s weight loss medicine, GLP-1, seems to temporarily reduce hunger signals in the brain’s “reward center.”
This marks the first time direct brain activity measurements have been taken from individuals receiving tirzepatide—marketed as Mounjaro for diabetes and Zepbound for weight loss—which showcased how the treatment affects what they call “eating noise.”
A report published on Monday revealed the findings regarding tirzepatide in one patient, although researchers stressed that these findings shouldn’t be applied broadly to others.
Yet, they suggested this could indicate a possible future role for Mounjaro and similar GLP-1 drugs in addressing particular eating disorders.
“We hope this report encourages deeper investigation into that possibility,” mentioned study leader Dr. Casey Halpern from the University of Pennsylvania’s Perelman School of Medicine.
The study tracked four participants involved in a clinical trial of deep brain stimulation aimed at treating uncontrolled eating disorders like bulimia nervosa. The approach involved monitoring the brain’s reward center, known as the nucleus accumbens, and using an implanted device to emit electrical impulses to curb signals that typically precede binge-eating episodes.
Interestingly, one patient had previously been prescribed tirzepatide for type 2 diabetes and obesity before receiving the electrodes. During the initial months of monitoring, she noted no cravings for food, and her nucleus accumbens was quiet.
In contrast, participants who weren’t taking tirzepatide often experienced increased activity in their nucleus accumbens, frequently becoming preoccupied with thoughts of food. This marked tranquility in her brain activity hinted that tirzepatide was playing a role in dampening food-related signals, according to the researchers.
Dr. Halpern remarked, “At one point, the activity in her nucleus accumbens was so subdued that I questioned if our system was functioning correctly.”
The effects of drugs fade over time
However, after five months, the researchers observed that tirzepatide’s effects on the patient’s behavior were not long-lasting—the so-called “meal noise” began to resurface.
Signs of activity consistent with bulimia reappeared, along with patient reports of severe food obsession.
Reflecting on this background, Halpern theorized that the temporary nature of tirzepatide’s effectiveness may stem from it being designed to combat diabetes and weight loss, rather than directly targeting conditions like bulimia.
Many widely used weight loss medicines replicate hormones found in the intestines and pancreas and don’t focus on influencing the brain’s reward systems.
To effectively address severe food obsessions in the long run, Halpern noted that GLP-1 drugs would need reworking to specifically engage the nucleus accumbens and be tailored for mental health purposes.
