The people selling the clocks have the best results

IT IS a striking achievement: the chief executives of several leading longevity firms have, according to their own accounts, lowered their estimated biological age by a combined 62 years. The figure makes a splendid headline and suggests that the pioneers of the anti-ageing industry are living proof of their own technology. Yet the same number also illustrates a more uncomfortable truth. The people with the greatest financial incentive to show the best results are the ones publishing the most dramatic ones.

Biological age testing has become a venture-backed growth category. The diagnostics market was valued at $2.8 billion in 2025 and is projected to reach $4.5 billion by 2033, according to Grand View Research. The industry clusters around four technological approaches. Epigenetic-clock companies such as Elysium Health, TruDiagnostic and Generation Lab analyse DNA-methylation patterns — chemical marks on DNA that change over time — and translate them into a single age estimate. Blood-biomarker firms such as Function Health, InsideTracker and Mito Health reframe routine clinical labs through an ageing lens. Proteomics companies, including Olink and SomaLogic, measure thousands of proteins but remain research-only. Glycan-based testers examine sugar molecules attached to immune proteins.

Prices range from roughly $200 to $600 per test. Function Health charges $499 a year. TruDiagnostic's comprehensive package costs $499. Elysium offers its Index test from $299. Demand is strong enough that Generation Lab, a smaller player, has maintained a waitlist of over 1,000 people for its cheek-swab test. To a venture-capital audience, this is a market, not a curiosity. Function Health has raised hundreds of millions of dollars.

Here is where the system begins to creak. The most impressive biological-age reductions come from people who own the companies that sell the tests. Founders post dramatic before-and-after scores that validate their product, attract customers, and satisfy investors. A test developed by a company's scientific team is applied to the company's own leadership. The results are then published on the company's channels, using the company's proprietary scoring algorithm. It is not a scam in the sense of fraud — the methylation data may be genuine and the mathematics honest. But it is a textbook case of the salesman serving as the product's best customer.

To be sure, the underlying science is not fiction. DNA methylation does change with age, and population-level studies have linked certain epigenetic patterns to mortality risk. The epigenetic-clock concept, pioneered by Stephen Horvath and others, has appeared in thousands of peer-reviewed papers. A November 2025 study in Nature Ageing of 43,616 UK Biobank participants found that organ-specific protein clocks could predict disease risk. Glycan-based testing is backed by more than 300 peer-reviewed publications.

Yet the translational gap between population-level association and individual-level measurement is vast. Eric Verdin, the president of the Buck Institute for Research on Aging, found that his own biological age varied from 40 to 67 depending on which DNA-methylation clock was used. He told Medscape in June 2025 that the tools are "not ready for prime time". Matt Kaeberlein, founding director of the University of Washington's Healthy Aging and Longevity Research Institute, does not recommend these tests for medical purposes, describing them as having mainly "entertainment value". A December 2025 study in the journal Epigenomics concluded that fundamental technical and biological properties prohibit the current use of these algorithms at the individual level.

The trouble is structural. Different clocks measure different things, use different reference populations, and apply different statistical models. A score from Elysium's Index cannot be compared with one from InsideTracker's InnerAge or TruDiagnostic's SYMPHONYAge, because they are not measuring the same construct on the same scale. When founders claim to have "lowered" their biological age, the reader should ask: lower than what baseline, measured by which clock, run in which laboratory, and with what degree of analytical noise?

Even within a single platform, the signal is noisy. Blood-biomarker scores fluctuate daily based on diet, sleep, recent illness and stress. Epigenetic measurements are sensitive to sample quality, laboratory conditions and batch effects. Elysium claims its own test achieves replicate agreement within zero to 1.5 years; other clocks show three to nine years of variance. That range means a single person could plausibly record a "biological age" swing of nearly a decade simply from technical imprecision.

The incentive problem runs deeper than vanity. Companies that sell both testing and intervention — supplements, coaching programmes, or clinical services — have a built-in revenue loop. A customer takes a test, receives an elevated score, and is then offered a plan to lower it. The improvement is measured on the same platform, with the same proprietary algorithm, and reported back as a success. InsideTracker reports that 80% of customers improve at least one at-risk biomarker and 60% reduce their InnerAge on follow-up. Function Health analyses more than 100 biomarkers and sells recurring subscriptions. The model resembles a fitness app that charges you to measure your progress and then sells you the programme to improve it.

This is not inherently fraudulent. Feedback loops — measure, act, re-measure — can motivate behaviour change. Some of the interventions these companies recommend, from exercise to metabolic monitoring, have genuine preventive-medicine support behind them. A June 2026 study from UC San Diego found that GLP-1 receptor agonists... did reduce biological age scores and slowed the pace of cellular aging. Lifestyle factors... can reduce biological age by up to 3 years in just 8 weeks.

But the commercial packaging of these findings creates a different problem. When the metric of success is proprietary, non-standardised, and scientifically contested, consumers cannot easily judge whether improvement is real or artefactual. They cannot compare results across platforms. They cannot replicate the measurement independently. And they are paying hundreds of dollars a year to a company whose revenue depends on them returning for repeat tests.

The better answer would be standardisation and transparency. If the industry wants clinical credibility, it should submit its clocks to independent validation against hard outcomes — hospitalisation, disability, death — rather than against lifestyle proxies or internal benchmarks. The FDA, which has yet to approve any consumer epigenetic-age test, would be a useful arbiter. Until then, these products occupy the same uncertain space as at-home DNA ancestry kits: technologically impressive, commercially viable, and scientifically inconclusive.

The 62-year claim is a data point, not a verdict. It is impressive that longevity entrepreneurs are willing to be guinea-pigs for their own products. It is also precisely what one would expect from people whose business model depends on the plausibility of biological-age reduction. The question for investors, regulators and consumers is not whether anyone can produce a dramatic before-and-after. It is whether the measurement itself means anything at all.

Until the clocks agree with each other, that remains the problem.