Adults on weekly semaglutide, the active ingredient in Novo Nordisk's Ozempic and Wegovy, aged roughly 9% more slowly on a validated epigenetic clock than those on placebo. The finding comes from a randomized, placebo-controlled trial published in Nature Communications in May 2026 and led by researchers at UC San Diego School of Medicine.
The 32-week study followed 108 adults with HIV-associated lipohypertrophy, a condition marked by abnormal fat buildup around the abdomen and organs. The researchers urge caution about applying the result more widely.
"We are not saying that semaglutide reverses aging or makes people younger. What we are seeing is a signal that it may slow some of the biological processes associated with aging," said Michael Corley, PhD, an associate professor at UC San Diego School of Medicine and the Stein Institute for Research on Aging. He and colleagues stressed that much larger trials in the general population will be needed to confirm the effect.
What the epigenetic clock measured
An epigenetic clock reads chemical marks on DNA, known as methylation patterns, that shift as cells age. Instead of counting birthdays, the clocks estimate how quickly the body is aging at the cellular level by detecting age-related changes long before disease appears.
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The team used DunedinPACE, a "pace of aging" measure developed from decades of health tracking in a New Zealand birth cohort. They also used a second clock called PCGrimAge, which has been tied to all-cause mortality risk.
Both moved in the same direction. Participants on semaglutide showed a slower DunedinPACE reading and improvements on PCGrimAge, along with a broader pattern of slower aging across markers tied to inflammation and to the health of the blood, brain, heart, kidneys, liver, and metabolism.
Not just a weight-loss effect
The most striking part of the analysis is that the aging signal held up after researchers adjusted for changes in body mass index and inflammation markers. That points to semaglutide acting on aging biology through more than the pounds it takes off.
The proposed mechanism is that the drug calms chronic immune activation and shrinks the visceral and ectopic fat that drives inflammatory signaling. Both are known contributors to accelerated biological aging.
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A separate pilot study in npj Aging tested semaglutide over 24 weeks in adults with HIV and fatty liver disease. Roughly 42% of participants showed a slower DunedinPACE pace of aging, about 34% showed slower PCGrimAge, and nearly half saw longer telomeres, the protective caps on the ends of chromosomes that shorten with age.
What it means for readers now
The trial does not change how GLP-1 drugs are prescribed today. Semaglutide is approved for type 2 diabetes and chronic weight management, not for slowing aging, and the study was carried out in a specific patient group with a specific fat-distribution condition.
Anyone considering starting, stopping or switching a GLP-1 medication should talk to their doctor. Still, the finding fits a growing line of research suggesting that treating the metabolic drivers of chronic disease may also nudge biological aging in a healthier direction. Similar signals have shown up for four weeks of dietary changes and even for a daily multivitamin in earlier trials.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.