Semaglutide extends lifespan in older female mice, Nature study finds

Semaglutide lengthened the lives of older female mice and eased several biological processes tied to aging, according to a study published September 2, 2026 in the journal Nature ^[1][2]. The National Institutes of Health funded the work, which was carried out at the University of California, Berkeley, where Danica Chen, a professor of metabolic biology and nutrition, is the corresponding author ^[2].

Dosing began at 20 months of age, a point the NIH describes as when the effects of aging are most pronounced, and the drug was injected under the skin once a day ^[1][2]. Among animals treated for the remainder of their lives, median survival was 834 days, against 742 days for untreated controls, a gain of roughly 12% ^[1]; the NIH put the difference at nearly 100 days at the midpoint ^[2]. A second group received the drug for three months for laboratory testing ^[1][2]. Those mice scored better on measures of muscle and cognitive function, and gene expression analysis showed that hallmarks of natural aging, including increased inflammation and reduced regenerative capacity, were lower in the treated animals ^[2].

Semaglutide cut food intake by 24% ^[1]. The mice weighed less, and the loss came mainly from fat: fat made up a smaller share of body weight while lean mass made up a larger share ^[1]. After adjusting for body weight, the researchers found no significant group differences in movement, oxygen consumption, carbon dioxide production, respiratory exchange ratio or energy expenditure ^[1].

The team also compared the drug head to head with eating less. Over five months, one set of 20-month-old females got semaglutide while another ate a diet 24% lower in calories, matched to the feeding pattern of the treated animals ^[2]. Most physiological measurements held steady in both groups ^[2]. They parted ways on other fronts: the medicated mice moved above their own starting levels on exploratory behavior, spatial memory and blood sugar maintenance, and their metabolic rate was largely unchanged, while the calorie-restricted animals burned less energy ^[2]. In the paper, the authors describe GLP-1 receptor activation as a calorie restriction mimetic, but say it produced effects beyond those attributable to reduced calorie intake ^[1].

"These differences point to the possibility that GLP-1 drugs tap into a biological pathway independent of calorie restriction," Chen said ^[2]. Rafael de Cabo, a senior investigator at the NIH's National Institute on Aging, who wrote a commentary on the study, said most chronic diseases are deeply rooted in aging. "If GLP-1 agonists do indeed slow it down, then a wide range of clinical benefits is exactly what you'd expect to see," he said ^[2].

Why it matters for patients

No finding here shows that semaglutide, sold as Ozempic, Wegovy and Rybelsus, extends life in people. The NIH stated that the results "do not imply that similar results could be achieved immediately in humans," and that further clinical studies will be needed to determine the clinical efficacy of GLP-1s on longevity in human patients ^[2]. Whether any longevity effect exists in people, and whether it would stem from weight loss, lower food intake or a separate pathway, has not been established ^[2].

Several features of the experiment limit how far the results reach. Only female mice were studied, so outcomes in males have not been reported ^[1][2]. The animals were healthy older mice rather than people with type 2 diabetes or obesity, so the study says nothing about how the drug behaves in those patients at that age ^[2]. The dose and formulation used have not been disclosed in the paper's abstract or the NIH announcement ^[1][2]. For anyone already taking a GLP-1 medicine for an approved use, this research does not change what is known about those treatments in humans ^[1][2].

What happens next

The paper and the NIH announcement both appeared on September 2, 2026 ^[1][2]. The NIH pointed to additional clinical studies, including a recent post-hoc analysis of the SLIM LIVER trial, as necessary steps toward judging any effect of GLP-1s on longevity in people ^[2]. Chen said future clinical investigations may explore benefits in healthy aged individuals, which would broaden the use of these drugs beyond their current approved purposes ^[2]. No human trial designed to measure an effect on aging or lifespan is described in either document, and none has been announced ^[1][2]. The mouse research was supported by National Institute on Aging grants R01AG063404, R01AG063389 and R01AG082105 ^[2].