Weight-loss drug ingredient extends lifespan by 12% in aged mice, study finds

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Semaglutide — the active ingredient in the weight-loss drug Wegovy and the diabetes drug Ozempic — extended the remaining lifespan of already-aged mice by about three months, a new study has found. The mice had not been managed from a young age; they received the drug for the first time late in life, when little time remained.

According to the journal Nature, a research team led by Danica Chen, a professor in the Department of Metabolic Biology and Nutritional Sciences at UC Berkeley, published results of an experiment in which semaglutide was administered to 20-month-old female mice.

Semaglutide works by stimulating GLP-1 receptors. GLP-1 is a hormone released by the gut in response to food; it promotes insulin secretion and acts on the brain to suppress appetite.

Ozempic and Wegovy mimic this hormone and are used to treat type 2 diabetes and obesity. In recent years, additional benefits have been reported in heart, kidney and liver disease, as well as neurodegenerative conditions.

Lifespan extended even when drug given in old age

The research team injected semaglutide daily into 40 of 79 female mice aged 20 months, while the remaining 39 received saline injections, and monitored all of them until they died.

Half of the saline-treated mice had died by day 742, while those given semaglutide lived an average of 92 days longer — an increase of roughly 12 percent.

The semaglutide-treated mice ate 24 percent less than the saline group and also lost weight. Most of the weight loss came from fat: the proportion of body fat fell, while the proportion of lean tissue — including muscle — rose.

Survival curves for mice treated with semaglutide (gray) and saline (black). The horizontal axis shows age in days; the vertical axis shows the proportion of surviving mice. The dotted lines mark the point at which half the mice remained — day 742 for the saline group and day 834 for the semaglutide group. [Nature]

Separately from the lifespan experiment, the team administered semaglutide to mice of the same age for three months and then assessed their physical condition.

When placed in an unfamiliar environment, the semaglutide-treated mice explored more than the saline group. They also found their way out of a maze-like memory test — a perforated disk from which they had to locate an exit — more quickly.

In tests of muscle strength and balance, the treated mice held on longer while on a rotating rod and while clinging to an inverted wire mesh. They also ran farther on a treadmill before tiring.

Inflammatory markers also fell in the semaglutide-treated mice. Although stem cell counts declined, the density of cells filling the bone marrow was higher.

Genes involved in fat production and storage, as well as those that drive inflammation, showed reduced activity, while genes linked to insulin response and the clearance of damaged proteins became more active.

The research team said that as mice age, genes associated with inflammation and fat metabolism become more active, but semaglutide appeared to switch off those aging-related genes — mimicking caloric restriction by returning them to a less active state.

Caloric restriction remains the most robustly validated method of extending lifespan. It has long been established that reducing food intake — without causing nutritional deficiency — slows aging across a wide range of organisms, from yeast to humans.

Drug may not only slow aging but reverse some decline

The research team compared mice placed on actual caloric restriction with those given semaglutide.

The calorie-restricted mice ate in bursts whenever food was introduced into their cages, then went without for the rest of the day. The semaglutide-treated mice spread their intake across the day in small amounts.

The calorie-restricted mice became more active as they foraged for food, while the drug-treated mice showed no such increase in movement. The two groups lost similar amounts of weight and fat overall.

In memory tests, however, the drug-treated mice outperformed the calorie-restricted ones. The research team interpreted this as suggesting that GLP-1 drugs may not only slow age-related functional decline but could, in some cases, reverse it.

The team said it used only female mice to avoid confounding results from fighting and injuries among males. It also said no adverse reactions attributable to semaglutide were observed.

However, the researchers said clinical trials in elderly humans would be needed to determine whether the drug produces similar changes in the rate of aging and lifespan in people.

Reference

DOI: 10.1038/s41586-026-10940-7

Feng, Y., Barthez, M., Wang, Y. et al. Late-life semaglutide treatment slows ageing and extends lifespan in female mice. Nature (2026).

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