Rapamycin can add years to your life, or none at all – it’s a lottery

The longevity benefits of fasting or taking rapamycin are more like a lottery than a safe bet. The interventions were linked to a greatly extended lifespan less than a year ago, but a reanalysis of the data suggests that the benefits vary enormously between individuals.

“(They) can increase lifespan by a little or (they) can increase it by a lot,” says Tahlia Fulton of the University of Sydney in Australia.

The 2025 study analyzed 167 research papers across eight non-human species, including fish, mice, rats and rhesus monkeys. Fulton and her colleagues found that these animals lived longer, on average, if they were given rapamycin — a potential antiaging drug — or put on a caloric restriction regimen, which has been linked to longevity. The results led the team to conclude that the same probably applied to humans.

Now the researchers have looked at the spread of the responses to the long-term interventions among the individual animals and have found that the benefits were variable. This means that on an individual level, either taking rapamycin or making dietary restrictions with the aim of living longer is “probably beneficial, but you don’t know how beneficial”, says Fulton.

“Some individuals will live a lot longer, some will live a little longer and some may not live longer than they would have done anyway,” she says. “You have a bit of a lottery going on, and so you can’t guarantee that these treatments will increase a person’s lifespan.”

Fulton says the goal of a longevity intervention is to square the curve of a graph showing population size versus longevity. This means that more people would live longer, rather than just a few, seen with a sloping curve. “Squaring the survival curve means that everybody lives a very long, happy life, let’s say, until they’re 100 years old, and then you pretty reliably die at 100,” she says.

The latest research shows that neither dietary restrictions nor rapamycin square the curve. On the flip side of this, Fulton says expectations need to be tempered until more research is done to find out who benefits most from these approaches. “Hopefully, we can address individual genetic codes and life experiences and be able to say to them, ‘Okay, cool, this is exactly what you need to live your longest possible life.'”

Matt Kaeberlein of the University of Washington in Seattle points out that squaring the curve does not necessarily improve people’s years of healthy life. He says a more interesting question is whether “inequity in the health span” increases or decreases with longevity interventions, such as exercise.

Originally developed as an immunosuppressant for people undergoing organ transplants, rapamycin blocks the action of the mTOR protein, which is key in cell growth and division. At low doses, it has been shown to increase lifespan in animals such as flies and mice, possibly by protecting against DNA damage.