Stanford Medicine researchers have discovered a naturally occurring molecule called BRP that mimics Ozempic's weight loss effects in animal studies while avoiding several common side effects, including nausea, constipation, and significant muscle loss. The breakthrough relied on artificial intelligence to search through thousands of human proteins and identify this tiny 12-amino-acid peptide, which is now heading toward human clinical trials.

How Did AI Help Researchers Find This Hidden Molecule?

Finding biologically important peptides is like searching for a needle in a haystack. Prohormones are inactive protein precursors that enzymes cut into smaller fragments called peptides, some of which act as hormones that regulate metabolism and appetite. A single prohormone can be cut in multiple ways, producing hundreds of thousands of possible peptides. Traditional laboratory methods would require researchers to manually isolate and test enormous amounts of molecules to find the few with meaningful effects.

The Stanford team created a computer algorithm called Peptide Predictor that searched all 20,000 human protein-coding genes for specific sites where prohormone convertases typically cut proteins. They then narrowed the search to genes producing secreted proteins, a common feature of hormones, that contained at least four possible cleavage sites. This process reduced the field from potentially millions of candidates to just 373 prohormones, making the investigation manageable.

"The algorithm was absolutely key to our findings," said Katrin Svensson, assistant professor of pathology at Stanford Medicine.

Katrin Svensson, Assistant Professor of Pathology, Stanford Medicine

The Peptide Predictor algorithm estimated that one enzyme, prohormone convertase 1/3, could produce 2,683 distinct peptides from those 373 proteins. Researchers then focused on sequences most likely to affect the brain and selected 100 peptides to test in laboratory-grown neuron-like cells. One peptide stood out dramatically: BRP, made from only 12 amino acids, increased neuronal activity tenfold compared with untreated controls, far exceeding the threefold increase produced by GLP-1, the hormone that semaglutide mimics.

What Makes BRP Different From Ozempic?

The key difference lies in precision. Semaglutide, the active ingredient in Ozempic, activates receptors found throughout the body: in the brain, gut, pancreas, and other tissues. This widespread activation produces multiple effects, some beneficial and some problematic. BRP appears to act specifically in the hypothalamus, a small brain region that controls appetite and metabolism, without triggering the same cascade of effects elsewhere in the body.

When researchers tested BRP in lean mice and minipigs, an injection before feeding reduced food intake during the following hour by as much as 50% in both species. Over 14 days of daily injections in obese mice, treated animals lost an average of 3 grams, with nearly all the reduction coming from body fat, while control mice gained about 3 grams. The treated mice also showed improved glucose and insulin tolerance, measures of how effectively the body regulates blood sugar.

Behavioral testing found no meaningful differences between treated and untreated animals in movement, water consumption, anxiety-like behavior, or fecal production. The absence of changes in fecal production was especially notable because semaglutide can slow digestion and cause constipation. Researchers also did not observe the nausea-related responses or major muscle loss associated with some existing weight loss treatments.

Steps to Understanding BRP's Path to Human Testing

• Receptor Identification: Researchers are working to identify the cell-surface receptors that attach to BRP, which will help scientists understand exactly how the peptide changes appetite and metabolism.
• Mechanism Mapping: The team wants to map the full sequence of events that occurs after BRP binds to its receptor, providing a complete picture of how the molecule works in the body.
• Clinical Trial Launch: Katrin Svensson has co-founded a company that plans to begin clinical trials of BRP in humans in the near future, moving the discovery from animal studies toward real-world testing.

The research was published in Nature on March 5, 2026, with Laetitia Coassolo as the lead author and Svensson as the senior author. While the results remain limited to animal studies, the findings suggest that BRP may reduce appetite through a more focused biological route than existing weight loss medications. The discovery demonstrates how artificial intelligence can accelerate drug discovery by narrowing vast search spaces to the most promising candidates, potentially opening new avenues for treating obesity and metabolic disorders without the side effects that limit current treatments.