Could the Burmese python hold the secret to weight-loss jabs that are free of side effects? That’s the hope of research into the reptile’s remarkable ability to suppress its appetite.
While the snakes can swallow their own bodyweight in one sitting, they are also able to go for months without touching a single meal.
US scientists have now identified the key to their appetite control.
After feasting, they produce a chemical in their gut that suppresses any desire in their brains to eat more. Researchers believe this finding could lead to a new generation of alternatives to weight-loss drugs such as Wegovy, Ozempic and Mounjaro – crucially, without side effects such as nausea.
It’s one of a slew of new medical hopes emerging from studies of snakes that promise to help with everything from chronic pain to breast cancer.
But it is the potential of snakes to assist with weight loss that is generating some of the greatest excitement.
The idea is being explored by researchers at Stanford Medicine and the University of Colorado, who found that after digesting a meal a Burmese python’s gut produces a 1,000-fold increase of an appetite-suppressing chemical called para-tyramine-O-sulphate (pTOS).
This chemical is believed to send sensations of fullness to their brains after eating – and scientists now hope that it may be used to block hunger pangs in obese people.
After feasting, Burmese pythons produce a chemical in their gut that suppresses any desire in their brains to eat more
A report in the journal Nature Metabolism earlier this year showed how, after a meal, pTOS is generated in the python’s gut and liver, then travels to the hypothalamus in the brain, where it ‘activates neurons involved in regulating feeding behaviour’.
When scientists injected obese mice with pTOS daily for a month, the rodents lost nearly a tenth of their bodyweight. Further investigations suggested that pTOS is produced by bacteria in the python’s gut as a byproduct when breaking down food. Tellingly, when the research team knocked out the snakes’ gut bacteria with antibiotics, pythons no longer had post-meal surges of pTOS.
The hope is that pTOS could produce the same magic in humans.
Weight-loss jabs currently available work by mimicking the effect of glucagon-like peptide-1 (GLP-1), a hormone produced in the pancreas and by cells in the gut which briefly regulates appetite after a meal and slows the transit of food through the gut.
But they can cause problematic side effects, particularly nausea, vomiting, diarrhoea, and constipation, fatigue and muscle loss.
Yet none of these problems were seen in lab mice dosed with pTOS, according to the report in Nature Metabolism.
One of the study’s authors, Dr Yong Xu, a behavioural neuroscientist, said that now we ‘know that pTOS clearly suppresses feeding’, his team will investigate how pTOS changes the brain, to see if new drugs can be identified to use as appetite suppressants.
The study also found that humans have pTOS in their blood, but at much lower levels. And the researchers discovered that, in most samples, it rose slightly after a meal.
Interestingly, one individual showed a 25-fold increase, hinting that some lucky people among us may have actually developed stronger, python-like responses.
GLP-1 drugs were themselves inspired by another reptile – the venomous Gila monster lizard.
During long periods of starvation, Gilas are able to slow their metabolisms and maintain constant blood sugar levels, so they don’t die of hunger.
Thirty-five years ago Dr John Eng, an endocrinologist in New York, discovered the chemical in Gila monsters’ saliva that enabled them to do this.
He called it exendin-4 and realised that it was similar to GLP-1 in humans. In the wake of this, drug companies worked to create GLP-1 drugs.
Snakes – and their venom in particular – have already led to the development of many life-saving medications.
For example, angiotensin-converting enzyme (ACE) inhibitors, one of the most commonly prescribed drugs for high blood pressure, are based on the action of the South American pit viper.
People bitten by this snake suffer such a dramatic drop in blood pressure that they lose consciousness. In the 1960s, scientists discovered this is due to chemicals in the venom that prevent our bodies making a hormone called angiotensin-2, which narrows blood vessels. Blocking angiotensin-2 makes blood vessels relax, which lowers blood pressure as the vessels dilate.
This finding led to the development of ACE inhibitors – now 65 million prescriptions for them are written every year in the UK.
Meanwhile, tirofiban, a widely used anti-clotting drug, is derived from one of the world’s deadliest snakes: the saw-scaled viper.
Its venom causes catastrophic haemorrhages and victims bleed to death. In 1987, scientists isolated a chemical from the venom, called echistatin, which prevents human blood platelets sticking together and clotting.
Tirofiban is used to prevent clots forming in the arteries of patients’ hearts in the wake of heart attacks, or while people are having surgery to treat a blocked coronary artery.
Venom is believed to have so much potential medically that in February scientists at King’s College London announced a £2.6million project to use artificial intelligence to scan venoms for substances that may have medical benefits for humans.
Already new uses are on the horizon, with therapies for breast cancer and chronic pain, according to a 2024 report in the journal Medicine In Drug Discovery.
An enzyme in the venom of the horned desert viper can stop breast tumour cells spreading around the body and lodging in tissues by preventing them from using proteins as glue, the study authors revealed.
Another enzyme in the venom stops tumour cells growing blood vessels which are needed to feed their growth.
The same study also suggested that venom from the South American rattlesnake may ease chronic pain. A nerve poison called crotoxin has been isolated from the venom and has been found to alleviate severe pain in patients with cancer.
And in Malaysia, researchers found that snake venom may provide a weapon against antibiotic-resistant bacteria such as MRSA.
Snake venoms contain substances that kill bacteria, for example, by breaking up their protective membranes and destroying the proteins they are built from, according to research at Kebangsaan University in Kuala Lumpur, published in the journal Toxins in 2025.
Snakes have these bacteria-killing powers to protect themselves from being infected by bugs found in their victims’ blood.
‘The toxins in some snake venoms are very good at killing cells in bacteria and viruses,’ Professor Nick Casewell, director of the Centre for Snakebite Research and Interventions at Liverpool School of Tropical Medicine, told Good Health.
‘This could make them effective antibiotic or antiviral medicines.
‘Unfortunately, these snake venoms are also very good at killing human cells as well, which is the problem here.’
The Centre for Snakebite Research and Interventions features the UK’s only Home Office-accredited snake research facility. It houses the largest, most diverse collection of tropical venomous snakes in the UK, with more than 50 species.
The venom they provide underpins research into new anti-venom treatments.
Better anti-venoms are desperately needed worldwide, with snakebites killing around 100,000 people per year, and around four times that number experiencing life-changing injuries such as kidney failure, muscle damage that can lead to limbs being amputated, and paralysis.
In the quest for effective snakebite therapy, one man in the US has injected himself with snakes’ venom more than 850 times.
Since 2001, Tim Friede, a truck mechanic and amateur snake enthusiast, has been injecting himself with low doses of venom in a bid to build up immunity from the lethal snakes he began collecting as a schoolboy. He claims that he has since survived being bitten more than 200 times by many different species.
Now his alarming self-protection strategy could lead to better treatments for snakebites.
When scientists at Columbia University injected antibodies from his blood into mice, they protected the rodents from 13 of 19 medically important snake venoms – those with medical applications – according to a report in the journal Cell last year.
It is hoped that future work using antibodies derived from a human can avoid the risk of severe allergic reactions.
Current anti-venoms are made by injecting horses and sheep with low-dose snake venoms and harvesting their antibodies, but these can trigger life-threatening immune reactions in people, which limits their use to well-equipped hospitals.
Professor Casewell’s team is hoping to take anti-venom treatments to a first-aid level.
They are working on a drug that can save people’s lives regardless of the type of snake that bit them.
Different venoms have been analysed to find a common feature that could be blocked by a single drug. They now have two promising antidotes that will start human trials soon.
‘These are existing drugs that have already been passed as safe in humans for other uses,’ he said. ‘One has been used to treat heavy-metal poisoning. The other is a cancer drug that was shown in trials to be safe, but didn’t show sufficient efficacy so it’s never been used.
‘One very promising thing is that these are oral treatments.’
