A daily oral supplement containing inanimate gut bacteria could provide a cheaper and safer alternative to popular weight-loss medications like semaglutide. A recent small-scale clinical trial indicates that the postbiotic supplement helps individuals shed weight by naturally stimulating the body's production of GLP-1, an appetite-suppressing hormone.
GLP-1 receptor agonists have revolutionized obesity treatment, but high retail costs, recurring supply shortages, and troublesome side effects—such as persistent nausea, vomiting, and abdominal discomfort—lead nearly half of patients in the United States to discontinue treatment within a year. In response, researchers have been searching for affordable over-the-counter options capable of triggering the same natural metabolic pathways.
In the study, led by Dr. Chariharth Vivek Lal at the University of Alabama at Birmingham, 80 adults with overweight or obesity were randomly divided into two groups. Half received a commercial postbiotic supplement called ResM, while the other half took placebo pills for two months. ResM contains heat-killed Lactiplantibacillus plantarum—a bacterium naturally occurring in fermented foods such as kimchi and olives—alongside vitamins D3 and B12, chromium picolinate, and extracts of white mulberry leaf and fenugreek seed.
Previous research suggests that dead L. plantarum promotes beneficial gut microbes that secrete short-chain fatty acids, which in turn prompt intestinal cells to release GLP-1 into the bloodstream. Blood tests from the trial showed that participants taking ResM experienced a more than twofold increase in circulating GLP-1 levels, whereas no hormonal change occurred in the placebo group.
Over the eight-week period, participants taking the postbiotic lost an average of 2.6 kilograms (about 3 percent of their total body weight). Conversely, those in the placebo group gained an average of 0.5 kilograms. Notably, participants taking ResM reported fewer mild side effects, such as nausea and bloating, than those in the control group.
Independent experts maintain cautious optimism while highlighting key study limitations. Simon Cork, a senior lecturer at Anglia Ruskin University in the UK who was not involved in the trial, noted that because participant weights and pill compliance were self-reported, the findings require verification. Furthermore, a 3 percent weight loss falls short of the 5 percent benchmark typically associated with clinically significant improvements in blood pressure and metabolic health.
Researchers emphasize that larger, tightly controlled clinical trials involving hundreds of participants are necessary before postbiotic supplements can be directly compared to pharmaceutical GLP-1 drugs. Patients considering weight-loss supplements are advised to consult their doctor before starting any new regimen.