Could Python Blood Lead to the Next Generation of Weight-Loss Drugs?

Researchers discovered an appetite-suppressing molecule in python blood. If one day turned into a medication, it might lack some of the common negative side effects of GLP-1s

Sara Hashemi | Daily Correspondent

April 1, 2026

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Burmese pythons have pretty irregular eating habits. One of these giant reptiles can swallow an entire antelope whole and then go up to a year and a half without additional meals.

Now, scientists have identified an appetite-suppressing molecule that plays a big role in the animals’ extreme fasting. The findings, published March 19 in the journal Nature Metabolism, could lead to new weight-loss therapies that don’t have some of the negative side effects of popular existing drugs like Ozempic and Wegovy.

“Obviously, we are not snakes,” says Jonathan Long, a study co-author and pathologist at Stanford University, to Hannah Devlin at the Guardian. “But maybe by studying these animals, we can identify molecules or metabolic pathways that also affect human metabolism.”

Ozempic, Wegovy and many other new weight-loss drugs are part of a class called GLP-1s, short for glucagon-like peptide-1. They mimic a naturally occurring hormone that the gut releases after eating, which regulates blood sugar, slows down the emptying of your stomach and sends signals to your brain that communicate you’re full. The medications curb appetite, but many people taking them suffer from gastrointestinal side effects including nausea, stomach pain and diarrhea.   

Long and his colleagues had been studying pythons in the lab because a few hours after chowing down, the animals’ organs can expand by 50 percent or more and the creatures can expend more than 40 times their usual amount of energy. Once they’re done digesting meals, most of these responses return to fasting levels.

The sudden metabolism boost “is the equivalent of a Kentucky Derby racehorse going from standing to sprinting at the Derby, which is massive,” says Skip Maas, a study co-author and molecular biologist at the University of Colorado Boulder, to Jamie Leary at CBS News. “But pythons are doing this not just for a lap around the track, but for about six days straight.”

To understand how the snakes pull off the feat, the researchers examined the blood of young Burmese pythons weighing around 3.3 to 5.5 pounds, as well as their relatives, ball pythons. The snakes had been fasting for 28 days, then were fed a meal that was roughly a quarter of their body weight.

Comparing blood samples taken before and after eating revealed 208 metabolites—products made or used when breaking down food—that significantly increased soon after the snakes feasted. The level of one little-studied molecule, called para-tyramine-O-sulfate (pTOS), ballooned to more than 1,000 times its pre-mealtime amount. pTOS is also found in human blood, where its level rises after eating.

The researchers then administered pTOS to obese and lean laboratory mice. “We wondered whether this metabolite affected any of the post-feeding physiological changes in the snake,” Long says in a statement. Giving the molecule to the rodents didn’t result in the organ expansion or increased energy expenditure seen in pythons. Instead, it regulated “the appetite and feeding behaviors of the mice,” he says.

Obese mice given pTOS ate much less than mice that didn’t receive the molecule, and after 28 days, they had lost 9 percent of their body weight when compared with the control group.

Further experiments that tracked where administered pTOS traveled in the animals’ bodies showed that the molecule targets the hypothalamus, a brain region involved in hunger cues. That means it works a bit differently from GLP-1s, which, in part, act on the stomach.

“We’ve basically discovered an appetite suppressant that works in mice without some of the side effects that GLP-1 drugs have,” says study co-author Leslie Leinwand, a biologist at the University of Colorado Boulder, to the Guardian.

More research is needed before the study’s findings could contribute to new drugs, but it’s not the first time the natural world has helped scientists develop weight-loss therapies. We also have reptiles to thank for those GLP-1 drugs, which were originally created to treat type 2 diabetes. Gila monster venom contains a protein called exendin-4 that mimics human GLP-1 and lasts a long time in the body. A synthetic version of exendin-4 became the first GLP-1 approved by the Food and Drug Administration in 2005.

Sara Hashemi | Read More

Sara Hashemi is a science writer and fact-checker currently based in New York City. Her work has appeared in Sierra, The Body, Maisonneuve magazine and more.