Humans have always understood aging through the language of time. We reach for idioms like the clock ticking or the sands running out.

However, our biological age is only partially determined by time. Human cells regenerate and are reborn, resetting the hands of the clock every day through renewal. This means you could be 54 with the cells of a 24-year-old, depending on how well your body keeps up this process.

Over time, these repair and regeneration systems become less efficient. However, some people are better able to maintain them than others.

The longevity luminary, Nir Barzilai, studies precisely these forces. Barzilai is a geneticist and one of the world’s leading scientists in the field of aging research. He is a professor at the Albert Einstein College of Medicine, founding director of the Institute for Aging Research and currently directs the Longevity Genes Project, a genetics study of over 600 families of centenarians and their children.  

His field, geroscience, defines aging not as a single process but as a set of interconnected biological mechanisms that progressively erode the body's ability to repair and maintain itself. Researchers have identified 12 of these mechanisms so far, known as the hallmarks of aging. The entire discipline's goal is to prevent or reverse them.

While there's plenty of noise from immortalist prophets like Bryan Johnson, Barzilai studies the superaging. His research has uncovered several longevity genes that protect centenarians from cancer, dementia, cardiovascular disease, and type 2 diabetes. By halting the process of aging, geroscientists such as Barzilai hope to dramatically extend both healthspan and lifespan.

«The biology of aging is also the biology that drives disease,» says Barzilai. So, if we stop or reverse aging, we could also stop disease, so to speak. Effectively, aging is the potent amplifier that makes genes bloom into disease. 

«It's not that you get diabetes and then you get old. It's that you get old, and then you get diabetes,» he explains.

He points to Alzheimer's as the clearest example. You can carry the APOE4 gene — even in its highest-risk form, homozygous. «When you're born, or when you're 10 or 50, you don't have the cognitive dysfunction. You need the aging to bring it out. It's the same with other diseases. The major risk factor for every disease is aging.»

The same is true for high cholesterol, he says. «Cholesterol increases the risk of a heart attack threefold, but aging increases it a 1000-fold. Obesity increases the risk of diabetes fivefold, but aging increases it 500-fold.»

«Our revolution is about treating your health in order to avoid disease, rather than treating a disease. It’s all prevention,» he explains.

Four Miracle Drugs

It's important to Barzilai that the field has already had real successes. There are already four FDA-approved drugs that reverse or halt aging, he says, and interestingly, they're familiar names, several of which have made headlines recently. The most recognizable is Ozempic.

Along with metformin, SGLT2 inhibitors, GLP-1 agonists like Ozempic, and bisphosphonates are some of the most promising gerotherapeutic drugs.

These drugs act on the body in four distinct ways. First, they make cells measurably biologically younger. Second, in animal studies, they extend both lifespan and healthspan: old animals live longer and live better. Third, in human clinical trials, they prevented diseases they weren't designed to treat. And fourth, they lower overall mortality.

If a drug checks all four boxes, he argues, it’s acting on aging itself.

The part that matters most for anyone reading this in a doctor's office is that these drugs are already approved and established as safe. This means doctors can legally prescribe them for other purposes, a practice known as off-label prescribing. In theory, any doctor could prescribe them today.

Building a Real Biological Clock

For Barzilai, the next step is the design of a real physical biological clock.

«The major obstacle is that we don’t have a good measure, like cholesterol or glucose, of our biological age. We need a measure like that. We need a measure where we go to a clinic and the doctor does a test and says, ‹You know, you are two years older than your biological age.› He might say, ‹Exercise and take metformin,› and in four months you come for a second visit and you’re two years younger.»

The test would allow regular check-ins to track retro-aging progress and, in turn, unlock further medical breakthroughs. 

Getting there will take investments. However, the funding case is easier to make than it might sound. Prevention isn't just good medicine; it's good business. «The mode of prevention is lucrative because you have to start taking treatments sooner and use them for longer,» says Barzilai.

In line with this, Barzilai will be attending as a speaker at the Longevity Investors Conference 2026 in Gstaad, where he'll share the latest breakthroughs from his field.

While the sands of time run out for most of us around 80, geroscience could push the maximum lifespan to 120. With the right combination of retroaging research and investments, we might even be able to flip the hourglass.