TL;DR
Epigenetic clocks have moved beyond birthday prediction. Two recent shifts are reshaping the field: (1) clocks are now proven to respond to real interventions — weight loss, exercise, vitamins and drugs — giving researchers a faster way to test what works; and (2) scientists can now edit individual age-linked methylation sites and watch the clock change, opening the door to causal tests. Meanwhile, candidate anti-ageing drugs including rapamycin, metformin, senolytics, NAD+ precursors and GLP-1 agonists are in or entering human trials. None is proven to extend lifespan yet, but the pipeline is larger than ever.
1. Progress 1: Clocks Are Responsive — They Move With Interventions
The first generation of epigenetic clocks, led by Steve Horvath in 2013, was trained to predict chronological age. They were accurate but passive — like a thermometer. The field's most important recent advance is showing that clocks are thermostats, not just thermometers: they change when biology changes.
A 2024 preprint (subsequently influential) analysed 51 human interventional studies and found that many lifestyle and drug interventions produce measurable changes in DNAm ageing biomarkers. The 2026 Frontiers in Genetics review "Turning back time" compiled a comprehensive list of interventions that decrease next-generation clocks, including:
- Weight loss and bariatric surgery: associated with epigenetic age reduction.
- Exercise: aerobic and resistance training show small clock-slowing effects.
- Dietary changes: Mediterranean-style diets, caloric restriction and time-restricted eating.
- Stress reduction: meditation and sleep improvement.
- Supplements: a daily multivitamin slowed clock ticking in a 2026 Nature Medicine analysis.
- GLP-1 drugs: semaglutide slowed epigenetic aging in a 2026 HIV-associated lipohypertrophy trial.
The critical caveat: a younger-looking clock is not yet proven to mean a longer or healthier life. It is a promising biomarker, not a guarantee.
2. Progress 2: Epigenetic Editing — From Correlation to Causation
A 2025 Nature Aging study used CRISPR-based epigenetic editing to change methylation at individual age-associated CpG sites. The result: editing a single site could shift the genome-wide epigenetic ageing landscape. This is a big deal because it moves clocks from observational tools to experimental tools.
If specific methylation changes cause aspects of ageing, reversing them could become a therapeutic strategy. If they are merely consequences, clocks remain useful readouts but not drug targets. The next few years will test which is true.
🐢 Tortoise Wisdom
"A clock that runs backwards is exciting. A clock whose hands we can move on purpose is revolutionary. We are somewhere between the two."
3. Candidate Anti-Aging Drugs in 2026
| Drug / class |
Target / mechanism |
Evidence stage |
Key human trial |
| Rapamycin / rapalogs |
mTOR inhibition; autophagy, immune modulation |
Early human (PEARL trial) |
PEARL 2025: 1-year low-dose rapamycin showed safety and healthspan signals in healthy adults |
| Metformin |
AMPK, mitochondrial complex I, metabolism |
Large trial planned (TAME) |
TAME (Targeting Aging with Metformin): multi-morbidity prevention trial in older US adults |
| Senolytics (D+Q, fisetin) |
Clear senescent cells |
Small human trials |
Pilot studies in diabetic kidney disease, idiopathic pulmonary fibrosis; larger trials ongoing |
| NAD+ precursors (NMN, NR) |
Raise NAD+ levels; sirtuin activity |
Phase I/II human trials |
Short-term safety and metabolic marker studies; no long-term lifespan data yet |
| GLP-1 agonists (semaglutide etc.) |
Appetite, weight, inflammation, possibly autophagy |
Rapidly emerging |
Semaglutide slowed epigenetic aging in a 2026 Nature Communications HIV lipohypertrophy trial |
We have dedicated guides to rapamycin, metformin, senolytics and NAD+ precursors.
4. What Makes a Real Geroprotector?
The term "geroprotector" describes an intervention that delays ageing itself, rather than treating one disease at a time. For a drug to earn that label, researchers generally want to see:
- Consistent effects across multiple species, ideally including mammals.
- Improvement in validated biomarkers, such as epigenetic clocks, inflammation panels or functional measures.
- Delay of multiple age-related diseases, not just one condition.
- A plausible safety margin for long-term use in healthy people.
None of the current candidates ticks every box. Rapamycin has the strongest animal data but notable side effects. Metformin is safe but its geroprotective effect in humans is unproven. NAD+ precursors are popular but short on long-term human evidence. GLP-1 drugs are exciting but were not developed as longevity therapies.
5. UK Practical Takeaway
For UK readers, the most actionable message is that lifestyle remains the only proven geroprotector. The same behaviours that slow epigenetic clocks — regular exercise, sufficient sleep, a plant-rich diet, stress management and not smoking — are also the interventions with the strongest evidence for longer, healthier life. Drugs and supplements are adjuncts, not replacements.
7. FAQ
What is an epigenetic clock?
An epigenetic clock is a mathematical model that predicts biological age by measuring DNA methylation patterns at specific CpG sites. Examples include Horvath's first-generation clock and the newer GrimAge, PhenoAge and DunedinPACE clocks.
Can epigenetic clocks be reversed?
Some interventions — including weight loss, exercise, diet change and certain drugs — are associated with small reductions in epigenetic age. However, it is unclear whether these changes translate into longer or healthier life.
What drugs are being tested to slow aging?
Major candidates include rapamycin and rapalogs (mTOR inhibitors), metformin (TAME trial), senolytics such as dasatinib + quercetin, NAD+ precursors (NMN/NR), and GLP-1 receptor agonists such as semaglutide.
Should I take rapamycin or metformin for longevity?
Not without medical supervision. Both drugs have real side effects and are not approved as longevity therapies in the UK. Self-experimentation is risky and not recommended.