Scientists at the University of Alabama have identified a daily bacterial supplement that produced weight loss comparable to Wegovy over two months without causing side-effects.
The clinical trial evaluated a postbiotic pill containing heat-treated Lactiplantibacillus plantarum bacteria, which doubled levels of the appetite-suppressant hormone GLP-1 in the digestive tract.
The findings come as Britain enters a post-weight loss jab era. While slimming injections such as Ozempic and Wegovy remain popular, demand for oral alternatives has created pharmacy waiting lists of 100,000 patients following the launch of Wegovy and Foundayo tablets.
Unlike prescription injections costing upwards of £300 per month, postbiotic supplements containing Lactiplantibacillus plantarum can be purchased online for roughly £45 for a four-week supply, equal to about £1.50 per day.
The supplement relies on a specific by-product created when Lactiplantibacillus plantarum is killed using heat. Unlike probiotics containing live microorganisms, postbiotics consist of inanimate bacteria and their cellular compounds, which produce fatty acids that boost gut cells and maintain stability without needing to survive digestion.
Trial results and GLP-1 hormone doubling
The latest trial, which has not yet undergone peer review by fellow scientists, followed 80 overweight or obese adults in the United States. Researchers at the University of Alabama split the cohort, randomly assigning half to take the supplement while the other half received placebo pills.
Participants were instructed not to alter their diet or exercise habits during the study. After two months, subjects taking the supplement lost an average of around 3 per cent of their body weight, whereas participants in the placebo group gained 0.5 kg. By comparison, clinical trials show Wegovy patients lose roughly 4 per cent of their body weight over the same two-month period.
Blood tests demonstrated that levels of GLP-1, the gut hormone that signals fullness to the brain, more than doubled among participants taking the supplement. The supplement group also reported a reduction in food cravings and experienced fewer side-effects, such as bloating, gas, and stomach pain, than those given placebo.
Supplement ingredients and expert analysis
The specific product tested in the trial is sold online under the brand name ResM for £45 for a month's supply. In addition to the heat-treated bacteria, the formula includes vitamin D3 and vitamin B12 to support healthy bones and red blood cells, along with fenugreek extract, a plant seed derivative rich in fibre.
Professor Penny Ward, a pharmaceutical expert from King's College London, said the inclusion of fenugreek extract could also help stimulate GLP-1, meaning the bacteria alone may not be doing all the heavy lifting. The authors of the study, which was funded by the supplement company, say their findings suggest ResM is "safe and clinically effective for weight-management."
"Supplements like this, which can boost GLP-1 naturally, could well be used as an obesity-prevention tool in the future," said Naveed Sattar, professor of cardiometabolic medicine at the University of Glasgow, who was not involved in the study. He added that while early data on the supplement is "somewhat exciting," scientists "need to see more data."
Other experts told the Daily Mail that taking a daily dose could help patients keep weight off after quitting injections. Studies show that users put on an average of 1 to 1.8 lb per month after stopping weight loss jabs.
Probiotic alternatives and dietary sources
Earlier research has highlighted the weight loss properties of Lactiplantibacillus plantarum in live probiotic form, which can cost as little as 20p per pill from online chemists. A 2024 analysis of nine trials involving 667 people found that probiotics containing the bacteria helped patients lose weight.
"The [bacteria] can prompt other bacteria to produce short-chain fatty acids, and there's data to show that these acids can activate important cells in the gut," said Dr Madusha Peiris, a neurogastroenterologist at Queen Mary University of London. She added that this process "leads to the release of anti-hunger hormones" such as GLP-1.
Professor Ward said there may be little difference in benefit between pro- and postbiotics, noting that "there could be similar benefits with foods that contain the bacteria, such as probiotic yoghurt Actimel or kimchi." However, Dr Peiris warned against using the supplement to boost the effect of weight-loss jabs, recommending it as a transition pill instead: "I think it's better to use it after coming off GLP-1 drugs, rather than use it alongside them, because you don't want to have too much of these hormones circulating in your body."
Because researchers did not track participant diets or exercise routines during the ResM trial, they noted that unmonitored lifestyle changes could not be ruled out as contributing factors. Experts advise patients to consult a medical professional before taking supplements, warning that Lactiplantibacillus plantarum can trigger severe allergic reactions in some individuals, including face swelling, breathing problems, hives, rashes, and sickness.
Scientists have also studied other natural GLP-1 stimulants, including berberine, a plant compound often referred to as nature's Ozempic. A 2024 review published in the journal Archives of Physiology and Biochemistry confirmed that berberine increases GLP-1 production by altering gut bacteria and elevating short-chain fatty acid levels.
Safety concerns with weight loss injections
Demand for non-prescription alternatives is being driven in part by safety concerns surrounding injectable weight loss medications. A Daily Mail analysis of official drug safety data published this month revealed that 216 deaths in the UK have been linked to slimming jabs, including Mounjaro, Ozempic, and Wegovy.
Health records document approximately 150,000 suspected adverse reactions associated with the injections since 2010, of which 18,000 were serious or fatal. The figures follow recent reports of two additional UK deaths linked to the drugs.
Caroline Savage, a 73-year-old British grandmother, died after increasing her dosage of Mounjaro, which caused faecal peritonitis when bacteria leaked into her abdomen through a hole in her bowel. In a separate case, 19-year-old student Josephine Nasr suffered a fatal cardiac arrhythmia in her dorm room at the University of East London. Ms Nasr, who was overweight but not obese, had been prescribed tirzepatide, the active ingredient in Mounjaro, in California, where she was born.
A coroner concluded that, on the balance of probabilities, the tirzepatide caused low blood sugar, inducing an electrolyte imbalance that interacted with an underlying heart condition to trigger the fatal heart rhythm.
