Stanford Found a Tiny Peptide That Cuts Appetite Like Ozempic — Without the Nausea

Researchers at Stanford Medicine have found a naturally occurring peptide — a tiny protein fragment your body already makes — that appears to cut appetite and drive fat loss in animals with none of the nausea, constipation, or muscle loss that come with drugs like Ozempic. The peptide, called BRP, works on a completely different part of the brain than existing weight loss drugs. And it was discovered not by years of traditional lab work, but by an AI tool the team built specifically for this search.

The results were published in Nature in April 2026.

The Problem With How Ozempic Works

Semaglutide (the active ingredient in Ozempic and Wegovy) works by mimicking a hormone called GLP-1. It's remarkably effective — people lose 15% or more of their body weight on average. But GLP-1 receptors aren't only in the brain. They're also in the stomach, gut, and pancreas. That's why the drug causes nausea, slows digestion, lowers blood sugar, and in some people, leads to muscle loss alongside fat loss. The drug is doing a lot of things at once because its target is everywhere.

BRP takes a narrower path. It appears to act specifically on the hypothalamus — the part of the brain that controls hunger and energy use. In theory, a compound that only speaks to the brain's appetite center could produce the weight loss effect without the digestive fallout. That's the core of what makes this finding interesting.

How AI Did What Traditional Methods Couldn't

The body produces thousands of hormones and hormone fragments. Many start out as larger inactive proteins — called prohormones — that get snipped into smaller active pieces by enzymes. The problem is that each prohormone can be cut in dozens of different ways, producing fragments that could be biologically active or completely inert. Telling the difference using conventional lab methods is slow, expensive, and largely guesswork.

The Stanford team built a computer tool they called Peptide Predictor. It scanned all 20,000 human protein-coding genes looking for prohormones that could be cut into peptide hormones — focusing specifically on proteins that are secreted outside cells (a hallmark of hormones) and that have multiple cutting points. That narrowed the field from 20,000 proteins down to 373 prohormones, which the algorithm then processed into 2,683 possible peptide candidates.

From those, the researchers hand-picked 100 to test on lab-grown brain cells — including GLP-1 as a known benchmark. BRP wasn't one of the obvious candidates. It's just 12 amino acids long, which is tiny even by peptide standards. But when tested, it activated appetite-controlling neurons at ten times the strength of the control cells. GLP-1, the basis of the most successful weight loss drug ever made, produced a noticeably weaker response.

What Happened in Animals

After the cell results, the team tested BRP in both lean mice and minipigs. Minipigs were included specifically because their metabolism and eating patterns are closer to humans than mice are — a deliberate attempt to get results that might actually translate.

A single injection of BRP before a meal reduced food intake by up to 50% within an hour. In obese mice given daily injections for two weeks, the animals lost an average of 3 grams of body weight — almost entirely from fat. Untreated mice gained about 3 grams over the same period. The treated animals also showed better responses to glucose and insulin, suggesting metabolic improvements beyond just eating less.

Crucially, the researchers looked specifically for the side effects that plague existing drugs. The animals showed no changes in movement, no increased anxiety, no change in how much water they drank, and no disruption to their digestion. Further analysis confirmed that BRP activates different brain circuits than GLP-1 — it's not just a weaker version of the same thing, it's working through a distinct pathway.

Where This Stands Right Now

BRP is early-stage research. Animal studies — even in minipigs — are a long way from human clinical trials, and most compounds that look promising in animals don't make it through human testing. The researchers themselves are careful about this: they still need to identify exactly which receptors BRP binds to, understand how it's broken down in the body, and figure out how to make its effects last long enough to be practical as a drug.

That said, the team is moving forward. Katrin Svensson, the study's senior author and an assistant professor of pathology at Stanford, has co-founded a company called Merrifield Therapeutics specifically to develop BRP toward clinical trials. Human trials are described as planned for the near future.

The context matters here. Semaglutide and tirzepatide have been transformative — weight loss results that were previously only seen with surgery, achieved with a weekly injection. But they're not tolerated well by everyone, and the side effect profile keeps a meaningful portion of patients from staying on them long-term. A compound that could deliver comparable appetite suppression without gut involvement would address one of the most significant unmet needs in obesity medicine.

"Nothing we've tested before has compared to semaglutide's ability to decrease appetite and body weight," Svensson said. "We are very eager to learn if it is safe and effective in humans."

A Note on What BRP Is

BRP stands for BRINP2-Related Peptide — named after the larger protein it's derived from (BRINP2, or BMP/retinoic acid inducible neural specific 2). It is naturally produced in the body, which puts it in a different conceptual category than synthetic drugs. Whether that biological origin translates into a better safety profile in humans remains to be tested. But it's part of why the discovery is generating attention beyond the usual new-drug coverage.

The research involved scientists from Stanford, UC Berkeley, the University of Minnesota, and the University of British Columbia. Funding came from the National Institutes of Health, the American Heart Association, the Carlsberg Foundation, and Stanford's Wu Tsai Human Performance Alliance.

Source: Stanford Medicine, Nature, April 2026. Laetitia Coassolo et al. Svensson and Coassolo are listed as inventors on patents related to BRP for metabolic disorders.