Study Reveals How New Weight-Loss Drugs Reshape the Brain

New, oral GLP-1 drugs "can reduce not just hunger, but the desire to pursue rewarding food. They’re acting on the system that makes you want the cake, not just the system that makes you feel full.”

That's the conclusion of a recent study led by University of Virginia Prof. Ali Guler and published in Nature.

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.”

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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.

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.”  – Russ Bahorsky, University of Virginia College of Arts and Sciences