UVA Study Reveals How New Weight-Loss Drugs Reshape the Brain

If you’re considering taking one of the new generation of GLP-1 weight-loss drugs, you may expect it to help curb feelings of hunger, but what you may not expect is something a little less appealing: a radical change in how you experience food and the enjoyment of eating.

In a study published in Nature, a team led by UVA neuroscientist Ali D. Güler found that a new class of oral GLP-1 drugs can directly influence brain circuits tied to reward and motivation, not just hunger, meaning they have the ability to reshape not just appetite but the desire for food itself — an effect that could help explain both the drugs’ success and their more puzzling side effects.

“These drugs are incredibly effective,” Güler said. “But what we wanted to understand is what they’re doing in the brain.”

More than Just an Appetite Suppressant  

GLP-1 drugs were originally developed to treat Type 2 diabetes by improving insulin response, and their weight-loss effects were initially considered a side benefit. Güler’s team wanted to dig a little deeper into how the drug worked, focusing on not just its affect on insulin but on what else it might be doing in the body.

Using a unique, genetically engineered mouse model, the researchers demonstrated that newer small-molecule GLP-1 drugs — such as recently approved oral medications — can reach deep regions of the brain. Scientists have long understood that these drugs act on neurons in the hindbrain, a region that helps regulate basic functions and contributes to feelings of fullness and nausea. The UVA team found that, in addition to those established effects, the drugs also engage a separate circuit linking the hindbrain to the central amygdala, which is involved in processing emotions, and ultimately to dopamine-producing neurons. That pathway plays a critical role in how the brain assigns value to rewarding experiences like eating high-calorie foods.

“What we show is that these drugs can reduce not just hunger, but the desire to pursue rewarding food,” Güler said. “They’re acting on the system that makes you want the cake, not just the system that makes you feel full.”

The findings also help explain differences among drugs in this rapidly growing class. Some compounds appear to produce more nausea-like effects, while others create a distinct brain state that reduces food motivation without the same level of discomfort.

Implications for Industry and Society

The discovery arrives as pharmaceutical companies race to develop cheaper, more accessible alternatives to injectable GLP-1 drugs. Oral medications are easier to produce, more shelf stable and significantly less expensive, which could make them accessible to millions of people — a market that could mean profits of hundreds of billions of dollars in the coming years, according to Güler. But the study also raises important questions.

“If these drugs are affecting reward pathways in the brain, that has implications beyond weight loss,” he said. “It could influence things like addiction, impulse control or even how people experience pleasure.”

Early evidence also suggests some patients find it easier to quit smoking or curb other compulsive behaviors while on GLP-1 drugs. Others report a diminished sense of enjoyment from eating. Güler sees both sides as reason for deeper investigation.

“As scientists, our job is not just to say that something works,” he said. “It’s to understand how it works, so we can improve it and anticipate unintended consequences.”

He also cautioned that as these drugs become more widespread, regulation and oversight will be critical, particularly as lower-cost formulations expand access.

“These are powerful compounds,” he said. “We need to understand them fully as they move into everyday use.”

Student-Driven Discovery

The research represents not just a scientific breakthrough, but a major educational achievement.

The study spans the equivalent of at least three doctoral dissertations, with three co–first authors each leading a major component of the work, from developing the animal model to mapping neural circuits and analyzing behavior.  

More than a dozen undergraduate students also contributed, working in close collaboration with graduate researchers who effectively ran “mini-labs” within the project.

“On the ground, the experiments were designed and executed by the students,” Güler said. “They’re the ones who made this happen.”

The project took roughly five years to complete and reflects the highly collaborative culture of UVA’s biology department and neuroscience programs.

“It shows what students can do when they’re given the opportunity and support,” Güler said. “This is training the next generation of scientists in the most hands-on way possible.”

"Working on this paper has been one of the most formative experiences of my graduate career,” said Isabelle Sajonia, a fourth-year Ph.D. student in biology and a co-lead author of the paper. “Navigating the review process taught me resilience and refined my ability to tell a compelling scientific story, and those skills have already paid off in landing a fellowship to fund my final PhD year."

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Unlike many large-scale neuroscience studies, the research was not primarily driven by federal grants. Instead, it was made possible through internal support at UVA with funding from its Brain Institute, seed funding from Arts & Sciences and other University programs.

Güler said those investments were not simply supplemental — they were essential to the work.

“None of this work was directly funded by NIH,” said Güler. “These programs gave us the flexibility to take risks, support students and sustain a long-term project that would have been very difficult to do otherwise.”

Those relatively modest awards helped fund years of experimental work, particularly in an area where costs can be high and timelines long. They also allowed graduate students to dedicate significant time to the project, accelerating progress and enabling the kind of sustained inquiry necessary for a publication in Nature.

For Sarah Kucenas, associate dean of research for Arts & Sciences, the study reflects a central institutional priority: investing early in people and ideas to drive discovery.

“This research shows how targeted, early-stage support can have an outsized impact,” Kucenas said. “By investing in interdisciplinary work and empowering our students as researchers, we create the conditions for discoveries that resonate far beyond Grounds.”

Looking Ahead

Güler and his team are now working to better understand the natural role of the brain circuits they identified, as well as how different drugs may target them more precisely.

“This is just the beginning,” he said. “If we understand these pathways, we may be able to design treatments that target specific behaviors — whether that’s overeating, addiction or something else entirely.”

As GLP-1 drugs become more widely used, researchers say a deeper understanding of their neurological effects will be essential, not only to improve their effectiveness, but also to anticipate how they may shape behavior and well-being over time.

“This is about knowing what these drugs are really doing,” Güler said. “The more we understand, the better we can make them — for patients and for society.”