GLP-1 drugs are transforming medicine—from treating obesity to diabetes to kidney and heart disease to sleep apnea. And now some telehealth companies are pitching them as a potential route to something more elusive—a longer and healthier life.
Specifically, microdoses of GLP-1s—little fractions of approved dose amounts—are being marketed as a way to tamp down inflammation, protect the brain and slow aging. A microdose of GLP-1 just means anything below the minimum dose approved by the U.S. Food and Drug Administration. Longevity influencer Bryan Johnson, for example, in 2024 described taking 0.5 milligrams of tirzepatide a week for longevity. He quit a few weeks later after his resting heart rate increased, however. And all promise of microdosing stems from a still-emerging body of evidence—a lot of which is in animals.
There are decades of research showing that calorie restriction extends lifespan. Because GLP-1 drugs reduce food consumption, researchers wondered whether they could mimic this effect. “It was kind of logical to think about drugs that reduce calorie intake and reduce weight,” says Nicolas Musi, an endocrinologist who directs the Diabetes and Aging Center at Cedars-Sinai in Los Angeles. But for years it remained a theory, he says.
On supporting science journalism
If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
In September Danica Chen, a professor at the University of California, Berkeley, and her team found evidence that GLP-1s might have an effect on longevity in mice. Twenty-month-old female mice that were given daily semaglutide injections ate about a quarter less than control mice and lived almost 100 days longer. They also scored better on strength and memory testing and showed fewer molecular signs of aging, such as inflammation.
To see whether eating less explained these effects, the researchers compared the drug with a diet that reduced food by the same amount. The two treatments had similar effects in several areas, but on measures of memory, exploratory behavior and blood sugar control, the semaglutide mice outperformed the calorie-restricted mice, suggesting “some mechanism that is independent of reduced food intake,” Chen says. The study used a dose equivalent to the standard. “We don’t know whether microdosing would have the same benefits,” she says.
The mouse data on longevity “is very, very compelling,” Chen says. “But before we get the data in humans, we just cannot say for sure.”
Post hoc analyses of human trials suggest GLP-1s slow molecular clocks that estimate biological age, which hints that the drugs might do more than just promote weight loss. But these trials have relied on standard doses rather than microdoses and are often in people who are overweight or have other comorbidities. Whether GLP-1s might extend the lives of healthy people, at any dose, remains unclear.
In a small trial of adults with HIV and excess abdominal fat, semaglutide slowed their epigenetic clocks, which estimates biological age. When the team accounted for changes in body mass index and inflammation, some of the benefits remained. “It’s not completely just due to weight loss,” says Michael Corley, an aging researcher at the University of California, San Diego, who led the study.
Other studies have found similar results. In October Novo Nordisk, which makes Wegovy and Ozempic, presented new analyses of their earlier trials at a longevity research conference. In a preprint that hasn’t been peer-reviewed, the hearts, kidneys and brains of people on semaglutide appeared up to four years younger based on organ-specific biological aging clocks.
Musi says it’s too early to say if the drugs extend life or improve health over the long term, and exactly how GLP-1s might exert these effects is also unclear. Eating less and losing weight can reduce inflammation on their own, so some benefits may be indirect, Musi says. But there are some “hints” of direct effects of the drugs, he says.
It’s possible that the drugs could be influencing several processes thought to drive aging. One of these is chronic inflammation, which rises with age and is linked to heart disease and dementia. Another is cellular senescence, in which damaged cells stop dividing by remaining in tissues, and the decline of mitochondria, which supply cells with energy. In Chen’s mouse study, semaglutide reduced inflammation, cellular senescence and mitochondrial damage. But whether microdoses might show these same signals remains to be seen.
Most of the evidence for taking a smaller dose is for those trying to keep weight off. But microdoses are far smaller and may not deliver the benefits seen at full doses, Musi says. Many products sold as microdoses are also compounded, so they aren’t regulated by the FDA in the same way as approved drugs. As a result, some people may be taking different formulations than they think, Corley says.
For any healthy person considering microdosing GLP-1s for longevity, “I would definitely not recommend it at this point,” Corley says. Diet, exercise and sleep are still the gold standard, he says, and for someone already working on those, “there’s no indication that adding GLP-1s with microdosing is going to make a meaningful benefit.”
