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Biological Age Testing
Fishtown Medicine•6 min read
4.96 (124)

Biological Age Testing

Ashvin Vijayakumar MD

Medically Reviewed

Ashvin Vijayakumar MD•Updated May 2, 2026
On This Page
  • Your Birthday Is Not the Whole Story
  • What Are Epigenetic Clocks and Why Do They Matter?
  • Which Tests Do We Actually Use at Fishtown Medicine?
  • What Can Actually Move the Number?
  • Guidance from the Clinic
  • Actionable Steps in Philly
  • Common Questions
  • Can I really reverse my biological age?
  • Is telomere testing useful?
  • Does insurance cover biological age testing?
  • How often should I retest my biological age?
  • What is the difference between GrimAge and DunedinPACE?
  • Are at-home spit kits as accurate as clinical blood draws?
  • How long does it take to see changes on a test?
  • What lifestyle factors most affect biological age?
  • Deep Questions
  • Can biological age testing predict cancer or heart disease risk?
  • How does inflammation affect my methylation clock?
  • Can supplements truly slow biological aging?
  • Are there contraindications or risks to testing biological age?
  • How does biological age testing compare with VO2 max or DEXA?
  • What if my biological age is younger than my real age?
  • Can methylation tests detect early disease before symptoms?
  • How do GLP-1 medications and metformin affect biological age?
  • Are biological age tests safe and accurate during pregnancy?
  • How do biological age tests perform across different ethnic backgrounds?
  • What is the cost of biological age testing in Philadelphia?
  • How do you build a personalized plan around biological age results?
  • Can biological age be used to track a medication or therapy?
  • How does Philadelphia's environment factor in?
  • Scientific References

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TL;DR30-second take

A biological age test measures how fast your body is aging at the cellular level, separate from your birthday. The most reliable type uses DNA methylation patterns (small chemical tags that turn genes on and off) to estimate biological age and the pace of aging. Telomere tests are popular but less accurate for predicting healthspan.

Your Birthday Is Not the Whole Story

You have two ages. Chronological age is the calendar number you blow out candles for. Biological age is how fast your cells and tissues are actually changing. In Medicine 3.0, the second number often guides our plan more than the first. The catch is that the online market is full of tests with weak science behind them.

If you search for "biological age test," you will see kits priced around $299 based on telomere length. I read those results with caution. Telomere length has only a weak link with mortality in large studies, and results can swing with hydration, an illness, or a stressful week.

The current clinical gold standard is the epigenetic methylation clock, a lab test that reads small chemical tags on your DNA that change with age and lifestyle.

What Are Epigenetic Clocks and Why Do They Matter?

Dr. Steve Horvath changed aging science by showing that DNA methylation patterns can predict health outcomes more accurately than your chronological age or even smoking status.

  • Telomeres. Often called the caps on the ends of your chromosomes. They do shorten with age, but the link to overall mortality risk is weak (correlation around 0.1).
  • Epigenetics. This measures which genes are expressed (turned on or off) through methylation. Picture it as the dust that builds up on your genetic controls and changes how the genes get read.
  • The data. The GrimAge clock predicts healthspan with strong accuracy. It tracks closely with inflammation markers (such as CRP) and overall function.

Which Tests Do We Actually Use at Fishtown Medicine?

In our practice, we use the TruDiagnostic or DunedinPACE algorithms because they have the best validation data and the most useful outputs.

  1. DunedinPACE. Think of this as your speedometer. It shows the pace at which you are aging right now. For example, a score of 0.85 means you are aging 0.85 biological years for every chronological year, slower than the calendar.
  2. GrimAge. This works like an odometer. It estimates the total biological wear your body has built up over your life so far.
  3. The goal. We aim for a DunedinPACE under 0.95. A score over 1.0 suggests your body is taking on biological damage faster than the calendar, which is the pattern we want to interrupt.

What Can Actually Move the Number?

While the term "anti-aging" is often marketing fluff, building biological resilience is a measurable goal.

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A 90-minute conversation with Dr. Ash. A written plan you can actually follow.

Start your intake
InterventionImpact on Epigenetic AgeMechanism
Caloric restrictionHigh.May turn on sirtuins, survival pathways linked with DNA repair.
Methyl donorsModerate.Nutrients like B12, folate, and TMG give your cells the building blocks to keep methylation cycles steady.
Stress reductionHigh.Long-term cortisol can strip methylation marks and may speed biological aging.
Exercise (HIIT)High.Helps clear senescent cells, the older cells that stop dividing but stay metabolically noisy.

Guidance from the Clinic

Dr. Ash
"Data is only valuable when we have a plan to act on it."

We have your back. At Fishtown Medicine, the goal is not to order tests and hand you a number. We interpret, explain, and advocate. You should feel like you have a Chief Medical Officer in your corner, one who fights for clarity and access.

> "Dr. Ash, my test says I'm 55, but I'm only 40."

My response is usually, "This gives us a valuable baseline to work from."

A higher biological age is not a verdict, it is a signal. It often points to environmental factors (poor sleep, nutritional gaps, or metabolic stress) outpacing your body's repair systems. We build a focused plan around sleep, metabolic health, and movement, then we re-test in about six months. We often see the number trend in the right direction as physiology improves.

Actionable Steps in Philly

Choose precision over convenience.

  1. Use a clinical-grade test. TruDiagnostic (TruAge) is our standard. The cost is around $400, but the depth of data justifies the investment for someone serious about optimization.
  2. Read app-based tests with nuance. Algorithms based on standard blood labs (such as PhenoAge) are useful, but they do not match the precision of DNA methylation testing.
  3. Watch the trend, not the week. Biological age moves with sleep, stress, and recent illness. We look at the trend over a year, not a single result.

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Scientific References

  1. Horvath S, et al. DNA methylation GrimAge strongly predicts lifespan and healthspan. Aging. 2019.
  2. Belsky DW, et al. DunedinPACE, a DNA methylation biomarker of the pace of aging. eLife. 2022.
  3. Fahy GM, et al. Reversal of epigenetic aging and immunosenescent trends in humans. Aging Cell. 2019.
  4. Levine ME, et al. An epigenetic biomarker of aging for lifespan and healthspan. Aging. 2018.
  5. Lu AT, et al. DNA methylation-based estimator of telomere length. Aging. 2019.
Medical Disclaimer: This resource provides clinical context for educational purposes. In the world of precision medicine, there is no "one size fits all." The right plan must be matched to your unique lab work, physiology, and performance goals. Consult Dr. Ash to determine if this approach is right for you, particularly if you have chronic health conditions or are taking prescription medications.

Frequently Asked Questions

Common Questions

You may be able to lower your biological age, at least on the test. Studies like the TRIIM trial suggest that targeted lifestyle and hormonal strategies can reduce biological age by one to two years over twelve months. The deeper goal is healthspan, the years you feel strong, sharp, and active.
Telomere testing has limited clinical use for most adults. Unless there is a known genetic telomere disorder in your family, methylation testing usually gives more actionable data. The marketing on telomere kits often outpaces the science.
Insurance does not cover biological age testing today. The medical system mostly treats aging as inevitable rather than something you can modify, so this is an out-of-pocket investment in your long-term plan. Some HSA and FSA accounts do allow it.
Most patients retest every 6 to 12 months. That gap gives lifestyle changes (sleep, training, nutrition, stress) enough time to register on the methylation clock. Retesting too often adds noise without much signal.
GrimAge is your odometer, a snapshot of total biological wear so far. DunedinPACE is your speedometer, the rate at which you are aging today. The two answer different questions, and most clinical reports give you both.
Saliva-based methylation tests can be high quality when the lab uses validated arrays and clean DNA extraction. TruDiagnostic uses a blood draw because blood gives more reliable methylation reads than saliva. For research-grade precision, blood is still the gold standard.
You usually need three to six months of consistent change before the test moves in a clear direction. Sleep, training, and metabolic health are the levers that move the number fastest. One bad week or one perfect week will not change much.
The biggest movers are sleep quality, regular exercise (particularly zone 2 cardio plus strength), metabolic health (steady glucose and ApoB), low alcohol use, and chronic stress management. Smoking is the single fastest accelerator we still see in clinic. Diet quality and time-restricted eating make smaller but consistent contributions.

Deep-Dive Questions

Biological age testing is not a cancer or heart disease screen. GrimAge does correlate with all-cause mortality and cardiometabolic risk in large studies, but it is not a replacement for ApoB, a CT calcium score, mammograms, or colonoscopy. We use it as one input among many.
Chronic low-grade inflammation tends to push your methylation clock forward. The GrimAge model actually includes inflammatory markers like CRP in its calculation. Calming inflammation through better sleep, training, and metabolic health often shows up as a slower pace of aging on the next test.
A handful of supplements have plausible signals on biological age, including methyl donors (B12, folate, TMG), omega-3s, and creatine. Most of the data is short-term and small. I treat supplements as supporting players. Sleep, training, and metabolic health do most of the heavy lifting.
The blood draw or saliva sample carries the same minor risks as any lab test. The bigger risk is psychological. Some patients fixate on the number or chase fad protocols based on a single result. We frame it as a tool, not an identity.
VO2 max measures cardiorespiratory fitness and is one of the strongest single predictors of healthspan. DEXA measures bone density and body composition, which drive function as you age. Methylation age adds a different layer, the cellular pace of aging. The three tests work better together than alone.
A biological age younger than your chronological age is good news, but it is not a free pass. We still optimize sleep, training, ApoB, and metabolic health. The goal is to keep the gap, or widen it, year over year.
Methylation tests are not a disease screen, but the data trends can flag rising risk. A pace of aging that suddenly accelerates often points to under-managed metabolic, sleep, or stress drivers. We use the trend as a prompt to dig deeper, not as a diagnosis.
Early data on metformin and on GLP-1 medications (such as semaglutide) suggests both may slow aspects of biological aging, mostly through better metabolic health. The direct epigenetic effect is still being studied. We track the methylation clock for patients on these medications when biological age is part of their plan.
Pregnancy changes hormones, blood volume, and inflammation in ways that can change methylation marks. Most labs do not validate biological age tests during pregnancy. We pause biological age testing during pregnancy and through the early postpartum window.
Most early epigenetic clocks were trained on populations of European descent. Newer clocks, including DunedinPACE and updated versions of GrimAge, are validated across more diverse populations. Accuracy is improving but is still better in some groups than others. We mention this caveat when we read your result.
In Philly, clinical-grade options like TruDiagnostic run around $400 per test. Direct-to-consumer telomere tests cost less, around $200 to $300, but the data is less actionable. App-based PhenoAge calculators that use standard labs are essentially free if your labs are already drawn.
We start by reviewing the test alongside your full panel, sleep data, training history, and goals. We then pick three to five high-leverage targets (such as deep sleep minutes, ApoB, glucose stability, VO2 max, and stress recovery) and build a 6-month plan. We retest at the end of that block to see what moved.
Yes, biological age can track the effect of a long-term medication or therapy when it is one of several markers. It works well alongside ApoB, fasting insulin, and CRP. We do not change a medication based on the methylation clock alone, but we use it as supporting evidence.
Philly's long winters, lower vitamin D, air-quality dips along I-95, and high-stress jobs all show up in our patients' biology. We look closely at vitamin D, sleep, and outdoor time, particularly for patients commuting on SEPTA in the dark months. Local context matters as much as the lab number.

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