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

The longevity benefits of fasting or taking rapamycin are more of a lottery than a sure bet. The interventions were linked to significantly increased life expectancy less than a year ago, but a reanalysis of the data suggests that the benefits vary widely among individuals.

“[They] may slightly increase the lifespan or [they] it can increase it a lot,” he says Tahlia Fulton at the University of Sydney, Australia.

The 2025 study analyzed 167 research papers from eight non-human species, including fish, mice, rats and rhesus monkeys. Fulton and her colleagues found that these animals lived longer, on average, when given rapamycin—a potential antiaging drug—or put on a calorie-restricted diet, which has been linked to longevity. The results led the team to conclude that the same is likely true for humans.

Now the researchers looked at the spread of responses to longevity interventions between individual animals and found that the benefits varied. That means that on an individual level, either taking rapamycin or dietary restriction to live 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 should have anyway,” he says. “There’s a bit of a lottery going on, so you can’t guarantee that this treatment will extend an individual’s life.”

Fulton says the goal of a longevity intervention is to square the graph of population size versus life expectancy. This means that more people would live longer than just a few, as seen in the sloping curve. “The quadrature of the survival curve means that everyone lives a really long, happy life to, say, 100, and then you pretty reliably die at 100,” he says.

The latest research shows that neither dietary restrictions nor rapamycin flattens the curve. Based on that, Fulton says expectations need to be tempered until more research is done to determine who benefits most from these approaches. “Our hope is that we can reach out to individual genetic codes and life experiences and be able to say, ‘Okay, great, this is exactly what you need to live your longest possible life.’

Matt Kaeberlein at the University of Washington in Seattle points out that squaring the curve doesn’t necessarily improve people’s years of healthy life. A more interesting question, he says, is whether “health inequality” 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 crucial for cell growth and division. At low doses, it has been shown to extend lifespan in animals such as flies and mice, possibly by protecting against DNA damage.

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