InsideTracker vs Function Health vs Outlive.bio: Which Biological Age Test Is Worth It?

InsideTracker, Function Health, and Outlive.bio (now rebranding as OneTwenty) represent three distinct philosophies in biological age and health optimisation testing. InsideTracker prioritises personalised action plans built around blood biomarkers; Function Health offers comprehensive panel coverage at a transparent flat fee; Outlive.bio integrates wearable data, blood work, and physician-guided prescriptions into a continuous care model. The best choice depends on your goals, budget, and how you intend to act on the results.

Key Takeaways

• Biological age refers to how well your body is functioning relative to your calendar age. Blood biomarker composites and epigenetic clocks are two distinct methods used to estimate it — and they measure different aspects of ageing.^5,6
• InsideTracker analyses up to 48 blood biomarkers across 10 healthspan categories, adds a proprietary biological age estimate called InnerAge, and generates personalised lifestyle and nutrition action plans. The membership costs approximately $149 per year, with comprehensive testing from $340 to $489 depending on tier.
• Function Health tests 160 or more biomarkers twice per year at a flat annual fee of $365 — reduced from $499 in November 2025. It provides breadth of data but limited personalised coaching; it works best as a data tool for people who already have a healthcare provider.
• Outlive.bio (recently rebranding to OneTwenty) is an integrated precision medicine platform in closed beta as of early 2026. It combines quarterly blood testing, wearable integration, AI coaching, and physician-guided prescriptions. It sits closer to concierge medicine than a standalone test.
• Epigenetic clock tests such as TruDiagnostic's TruAge Complete ($499 per test) add a layer of DNA methylation analysis that blood panels cannot provide. GrimAge and DunedinPACE have been validated in large human cohort studies as predictors of mortality and clinical decline.^1,2
• Most of these platforms are currently only available to residents of the United States. International users should verify availability before purchasing.
• No testing platform can diagnose or treat disease. Results from any of these services should be reviewed with a qualified healthcare professional before making significant health decisions.

What Are These Services Actually Testing? A Framework for Understanding

Before comparing platforms, it is helpful to understand the categories of markers these services measure — because not all biological age tests are measuring the same thing.

Standard blood chemistry panels measure indicators of metabolic function, organ health, and nutritional status that are routinely used in clinical practice. These include markers such as haemoglobin A1c (a measure of average blood glucose), lipid fractions (total cholesterol, LDL-C, HDL-C, triglycerides, and the more advanced cardiovascular marker ApoB), liver enzymes (ALT, AST), kidney function markers (creatinine, eGFR), thyroid hormones, and inflammatory markers such as high-sensitivity C-reactive protein (hsCRP). Research using large human cohort datasets, including a study of over 306,000 UK Biobank participants, has shown that combinations of circulating blood biomarkers can be used to construct biological age estimates that are predictive of mortality risk independent of chronological age.⁶ A separate investigation using the Berlin Aging Study cohort (n=1,517) confirmed that biological age composites derived from standard laboratory blood parameters across metabolic, cardiovascular, inflammatory, and kidney domains were associated with physician-observed morbidity and higher mortality hazards — findings that held even after adjusting for chronological age, sex, and education.⁵

Beyond standard blood chemistry, comprehensive platforms include hormonal markers (testosterone total and free, DHEA-S, oestradiol, FSH, LH, cortisol), longevity-specific markers (homocysteine, Lipoprotein(a), insulin, SHBG), heavy metals and micronutrient status (vitamin D, vitamin B12, magnesium, ferritin, zinc), and in some cases cancer-related signals. Function Health's 160-marker panel, for example, extends significantly beyond what a routine annual physical examination typically orders.

Epigenetic clock tests represent a separate and complementary category. Rather than measuring levels of proteins or metabolites in blood, these tests analyse patterns of DNA methylation — chemical modifications to the structure of your DNA that accumulate and change with age and lifestyle exposure. These patterns can be used to estimate biological age at a cellular level, and certain epigenetic clocks have been validated in human studies as predictors of health outcomes. This is discussed in more detail in Chapter 5 of this article.

A key principle for evaluating any of these services is that a comprehensive panel identifies more potential areas of suboptimal health, but more data is not automatically more actionable. The most useful test is one whose results you will understand, discuss with a healthcare provider, and act upon consistently.

InsideTracker: Features, Pricing, and Best Use Case

InsideTracker was founded in 2009 by researchers from Harvard, MIT, and Tufts University with a focus on applying longitudinal health data to personalised optimisation recommendations. It is one of the longest-established direct-to-consumer health analytics platforms in the longevity space.

What InsideTracker Tests

The flagship offering is the Ultimate blood test, which analyses up to 48 biomarkers across ten healthspan categories: cognition, fitness, endurance, strength, weight, heart health, sleep, stress, nutrition, and immunity. Biomarkers include standard metabolic and lipid panels, full thyroid function, inflammatory markers, hormones including testosterone and DHEA-S, micronutrient status (vitamin D, B12, ferritin, zinc), and glucose regulation markers. An add-on test for oestradiol and progesterone is available, which is relevant for women managing hormonal health. A DNA kit (US only) analyses genetic predispositions for 38 wellness traits and integrates with blood results to refine recommendations.

InsideTracker's proprietary InnerAge calculation is its biological age estimate. Using a machine learning model trained on longitudinal biomarker data, InnerAge computes a single number representing your estimated biological age and compares it to your chronological age. This is a blood biomarker-based estimate rather than an epigenetic measurement, which means it reflects your current physiological state but captures different information to DNA methylation-based clocks. InsideTracker reports that approximately 60% of members reduce their InnerAge score on a follow-up analysis.

Pricing

InsideTracker operates on a membership model. Membership alone costs $149 per year and allows users to upload blood results from their own healthcare provider for analysis. The most popular entry point is Membership plus the Ultimate test, priced at $489. For existing members, subsequent Ultimate tests are available at the member-exclusive price of $340. A bundle of four Ultimate tests plus membership is available from approximately $1,116 to $1,283 depending on the package selected. Mobile blood draws (at-home phlebotomist) are available in certain US states for an additional fee of approximately $119 per test. Blood testing is conducted through Quest Diagnostics laboratory locations.

InsideTracker is currently available in the United States and Canada. Canadian residents require a mobile blood draw. International users outside these regions can only access the platform by uploading their own blood test results from a local laboratory.

Best Use Case for InsideTracker

InsideTracker is well-suited to individuals who want structured, actionable guidance rather than raw data alone. Its defining feature is the personalised action plan — a prioritised list of dietary, exercise, supplement, and lifestyle recommendations linked directly to your specific out-of-range or suboptimal biomarkers. The platform integrates with wearable fitness trackers and delivers ProTips based on your latest results and daily activity. It is particularly well-regarded by athletes and active individuals tracking recovery and performance markers over time. For those willing to engage with the platform's recommendations and retest periodically, the longitudinal tracking capacity provides genuine value.

InsideTracker is less suitable for users who primarily want the maximum number of biomarkers at the lowest cost, or for those located outside North America who cannot access its blood draw network.

Function Health: Features, Pricing, and Best Use Case

Function Health was co-founded by Dr. Mark Hyman, a prominent figure in functional medicine, and launched commercially in 2023. It rapidly attracted a large user base and achieved a $100 million annual revenue run rate by early 2025, with approximately 200,000 subscribers. In November 2025, the company raised a $298 million Series B at a $2.5 billion valuation and simultaneously reduced its annual membership price from $499 to $365.

What Function Health Tests

A Function Health annual membership includes two rounds of blood testing per year through Quest Diagnostics: a comprehensive Annual Test covering more than 100 biomarkers, and a Mid-Year Test covering 60 or more biomarkers to track interim changes. The combined annual testing covers heart health, hormones, thyroid function, liver and kidney function, metabolic markers, heavy metals, nutrients, inflammation, cancer signals, and more — significantly more than the average annual physical examination, which typically assesses approximately 26 biomarkers.

Unlike InsideTracker, Function Health does not provide a named biological age score. Its value proposition is breadth: the sheer number of markers assessed means that areas of suboptimal health which would go undetected on a standard blood panel are more likely to be identified. The platform provides a personalised action plan, food guide, and supplement list based on results, and clinicians review findings and flag critical alerts. However, Function Health does not offer direct clinician consultations or prescription services as part of its core offering. For in-depth clinical interpretation or prescription management, users are expected to work with their own healthcare provider.

Pricing

Function Health charges $365 per year as of November 2025. This flat annual fee includes both the Annual Test and the Mid-Year Test. Additional single-biomarker or on-demand tests are available at member-only pricing. The service operates on a cash-pay model with no insurance coverage, though HSA/FSA funds may be eligible. Testing is conducted through Quest Diagnostics locations across the United States. Function Health is currently a US-only service.

Best Use Case for Function Health

Function Health is best suited to health-conscious individuals who want the broadest possible blood panel coverage at a predictable, transparent annual cost and who have an existing relationship with a healthcare provider for clinical interpretation. It is particularly compelling as a comprehensive baseline screen — especially for users who have never had full-spectrum testing and want to identify potential areas of concern across the widest range of body systems. The $365 annual price point for 160-plus markers and two rounds of testing annually is genuinely competitive relative to what individual comprehensive panels would cost if ordered separately.

Function Health is less suitable for users who want personalised coaching, a guided action plan with structured follow-through, or a named biological age estimate. Its model is data-centric; the depth of interpretation and follow-up depends heavily on the user's own health literacy or their external healthcare team.

Outlive.bio (OneTwenty): An Integrated Precision Medicine Platform

Outlive.bio was launched as a "Real-Time Longevity" (RTL) platform that integrates wearable device data, at-home biomarker testing, and physician-guided medical interventions into a single continuous service. As of late 2025, the company opened a closed beta at a founder pricing of $499 per year and has begun rebranding as OneTwenty — a name reflecting the ambition of supporting users to live healthily to 120. The platform remains in limited capacity access as of early 2026.

What Outlive.bio / OneTwenty Offers

The platform combines several components that are typically separated in the health optimisation market. Quarterly blood panels cover metabolic health, cardiovascular risk markers (including ApoB and Lipoprotein(a)), hormones, liver and kidney function, inflammation, and longevity markers such as homocysteine and DHEA-S. Wearable device data from Oura Ring, Apple Health, Withings, Fitbit, Dexcom, and others integrates with lab results in a unified dashboard. Smart scale and optional blood pressure monitor data contribute daily biometric signals. An AI health coach interprets patterns across all data streams and provides continuous guidance.

Crucially, Outlive.bio includes access to licensed clinicians who can prescribe medical interventions: hormone replacement therapy (HRT), testosterone replacement therapy (TRT), GLP-1 medications, peptides, and sleep therapies. Personalised supplement packs are planned for launch in Q1 2026. This prescription capability distinguishes it fundamentally from InsideTracker and Function Health, which are data and guidance platforms without prescribing capacity.

Because the platform is in closed beta with limited availability, it is important to note that features, pricing, and access terms may change. Users interested in Outlive.bio or OneTwenty should verify current availability and terms directly with the company before making decisions based on this overview.

Best Use Case for Outlive.bio / OneTwenty

This platform is best suited to individuals who want a comprehensive, medically-integrated approach that goes beyond data and recommendations to actual clinical management. It is positioned between standard consumer health testing and traditional concierge medicine, offering more medical support than InsideTracker or Function Health while remaining more accessible in price than conventional concierge programmes, which can cost $5,000 to $10,000 per year or more. It is the right choice for users who have already identified specific health targets — such as hormone optimisation, metabolic weight management, or sleep quality — and want physician-supervised interventions alongside continuous monitoring.

Outlive.bio is not appropriate for users who want a simple one-time test or who are primarily interested in understanding their biomarker baseline without clinical support. Its limited beta access also means it is not currently available to all prospective users.

Epigenetic Testing Add-Ons: TruDiagnostic, Elysium Index, and What They Add

Blood biomarker-based platforms provide valuable information about your current physiological state, but they do not directly measure epigenetic ageing — the molecular changes that accumulate in your DNA over time. For users who want a deeper picture of biological ageing at the cellular level, epigenetic clock tests serve as a complementary layer rather than a replacement for blood panels.

What Epigenetic Clock Tests Measure

Epigenetic clocks analyse patterns of DNA methylation — chemical marks on specific locations (called CpG sites) throughout the genome that change predictably with age and in response to lifestyle factors including smoking, diet, exercise, stress, and sleep. Different generations of clocks capture different aspects of ageing. First-generation clocks (Horvath, Hannum) were trained primarily to estimate chronological age. Second-generation clocks (PhenoAge, GrimAge) incorporated clinical biomarkers and mortality data, producing estimates more closely associated with healthspan. Third-generation approaches, including DunedinPACE, measure the pace at which the body is currently ageing rather than a static point estimate.

The GrimAge clock, developed by Lu et al. in 2019, was trained on data from the Framingham Heart Study and integrates DNA methylation-based surrogates for seven plasma proteins and smoking pack-years to generate a composite predictor of lifespan.¹ In a subsequent human study of 490 participants from the Irish Longitudinal Study on Ageing (TILDA), GrimAge age acceleration was associated with eight out of nine clinical outcomes including walking speed, frailty, polypharmacy, and all-cause mortality at up to ten years of follow-up — outperforming earlier clocks including Horvath and Hannum across all adjusted models.² Further evidence from a large US cohort study (n=2,105 NHANES participants, median follow-up 17.5 years) found that GrimAge age acceleration was the strongest predictor of overall mortality among nine epigenetic clocks evaluated, with statistical significance well beyond that of other clocks.³

DunedinPACE was developed from the Dunedin Multidisciplinary Health and Development Study, which tracked 1,037 individuals born between 1972 and 1973 from birth through multiple decades of follow-up. Rather than assigning a biological age number, DunedinPACE outputs a pace score: a value of 1.0 indicates you are ageing at a typical rate, 0.8 suggests you are ageing 20% slower than average, and 1.2 suggests 20% faster. This pace metric is considered particularly valuable in intervention research because it is sensitive to lifestyle changes over shorter timeframes than static biological age estimates. A longitudinal twin study involving Finnish female participants followed for 18 years found that GrimAge was a strong predictor of mortality even after controlling for shared genetic influences — supporting its use as a measure of lifestyle and environmental ageing rather than purely hereditary ageing pace.⁴

TruDiagnostic

TruDiagnostic is a CLIA-certified laboratory offering the TruAge Complete test, which provides several epigenetic measurements from a small at-home finger-prick blood sample. The test includes the exclusively licensed DunedinPACE algorithm, the SYMPHONYAge organ-specific clock system developed by Yale University researchers (which reports biological age across eleven organ systems including brain, heart, and liver), the OMICmAge algorithm developed in collaboration with Harvard University, and telomere length estimation. The single test is priced at approximately $499; quarterly testing packages covering four tests are available at approximately $998.

TruDiagnostic maintains one of the largest private DNA methylation databases in the world, with over 17,000 consented participants on their EPIC850k array, and collaborates with academic institutions including Harvard, Yale, Duke, Cornell, and UCSF on epigenetic research. Their CLIA certification and HIPAA compliance provide a baseline of laboratory quality assurance. The company recommends retesting every three months when tracking the impact of specific lifestyle or clinical interventions.

Elysium Index

The Elysium Index is an at-home epigenetic biological age test developed by Elysium Health in collaboration with Morgan Levine, PhD, formerly at Yale School of Medicine. It uses an Illumina chip to analyse between 100,000 and 150,000 methylation sites and reports a biological age alongside a Cumulative Rate of Aging score. Elysium Health is also known for its NR (nicotinamide riboside) supplement Basis. At the time of publication, the Elysium Index is available primarily in the United States.

Combining Blood Panels with Epigenetic Tests

For users who want the most comprehensive picture of their biological ageing, the most informative approach is to use a comprehensive blood panel service for ongoing monitoring of physiological markers alongside periodic epigenetic testing to track cellular ageing pace. The two methods are complementary: blood panels reflect your current metabolic and hormonal environment, while epigenetic clocks capture cumulative biological ageing history. It is worth noting that correlation between different biological age measures tends to be moderate rather than high, suggesting they capture different and partially distinct aspects of the ageing process.⁵

Platform Comparison: Markers, Pricing, and Best Fit

Choosing the Right Service: A Decision Guide by User Profile

The question of which platform is "best" is not meaningful in the abstract — it depends on what you are trying to understand and what you will do with the information.

If you are new to comprehensive health testing and want a structured starting point with guided recommendations, InsideTracker's combination of clear biomarker analysis, personalised action plans, and the InnerAge biological age estimate makes it one of the more accessible entry points. The wearable integration and longitudinal tracking add genuine ongoing value for those who test regularly.

If your primary goal is to understand the broadest possible picture of your internal health in a single annual investment, and you already have a healthcare provider to interpret results with you, Function Health's flat $365 fee for 160-plus markers and twice-yearly testing represents strong value. It is a data-first platform for health-literate users who do not need coaching infrastructure built in.

If you have already identified specific health targets — hormonal optimisation, metabolic management, sleep quality improvement — and want physician-supervised interventions alongside continuous monitoring, Outlive.bio's integrated model offers capabilities that neither InsideTracker nor Function Health can match. At the current founder pricing in closed beta, it also represents an unusual combination of depth and relative affordability compared to traditional concierge medicine. Prospective users should monitor its transition from Outlive.bio to OneTwenty and verify current access terms.

If you are specifically interested in tracking your pace of cellular ageing, measuring the impact of lifestyle interventions on your biological age at a molecular level, or accessing validated epigenetic algorithms including DunedinPACE and SYMPHONYAge, TruDiagnostic's TruAge Complete test fills a gap that blood panel services cannot address. It functions best as a complement to blood panel testing rather than a standalone service.

For users based outside the United States, the options narrow considerably. TruDiagnostic ships internationally to selected regions. InsideTracker allows non-US and non-Canadian users to upload blood results from local laboratories for analysis. Function Health and Outlive.bio are not available outside the US.

A Note on Using Testing Results to Evaluate Supplements

One practical application of these platforms that is directly relevant to supplement users is using repeated blood testing to evaluate whether a supplement protocol is producing measurable changes in the biomarkers it is intended to support. Vitamin D levels are directly measurable and serve as a clear indicator of supplementation adequacy. Homocysteine levels reflect folate, B12, and B6 status and respond measurably to supplementation in those who are deficient. Markers including magnesium (which requires RBC magnesium testing rather than serum magnesium for accurate assessment), ferritin, and omega-3 index can all be tracked longitudinally to understand whether your current supplement programme is achieving its intended effect.

Magnesium contributes to normal energy-yielding metabolism and to the reduction of tiredness and fatigue — an EFSA-approved health claim that reflects magnesium's role in multiple enzymatic processes. Vitamin B12 and folate contribute to normal homocysteine metabolism. Vitamin D contributes to normal immune function and normal bone maintenance. All of these markers can be tracked through any of the platforms described in this article, providing an objective means of evaluating whether your current supplement protocol is achieving adequate status levels.

Q&A: Biological Age Testing Explained

What is the difference between biological age and chronological age?

Chronological age is simply how many years you have been alive. Biological age attempts to capture how well your body is functioning relative to that calendar age. Two people who are both 50 years old may have very different physiological states — different metabolic markers, different inflammatory status, different rates of cellular ageing. Biological age estimates aim to quantify this gap. Blood biomarker composites estimate biological age from the current state of your physiology; epigenetic clocks estimate it from molecular ageing patterns in your DNA.

Is InsideTracker's InnerAge calculation the same as an epigenetic clock?

No. InnerAge is a blood biomarker-based biological age estimate, not an epigenetic measurement. It uses a proprietary algorithm trained on InsideTracker's longitudinal biomarker database to produce an age estimate from your current blood results. Epigenetic clocks such as GrimAge and DunedinPACE are calculated from DNA methylation patterns, which require a separate sample type (typically a blood spot or tube sent to a specialist laboratory). The two approaches measure different aspects of ageing and can be used in a complementary way.

Is Function Health worth it if I already get blood work at my annual physical?

A standard annual physical typically includes a complete blood count (CBC) and a basic metabolic panel (BMP) — covering roughly 20 to 26 markers. Function Health's 160-plus marker annual panel adds advanced cardiovascular risk markers (ApoB, Lipoprotein(a), hsCRP), full hormonal profiles, thyroid function, micronutrient status, inflammatory markers, and cancer-related signals that are not routinely ordered. Whether the additional breadth is worth the cost depends on whether you have health areas of concern that standard panels do not address, and whether you have a healthcare provider willing to engage with the results.⁶

What is DunedinPACE and why is it considered a valuable ageing metric?

DunedinPACE is a third-generation epigenetic clock developed from the Dunedin Multidisciplinary Health and Development Study, which followed over 1,000 individuals from birth through multiple decades. Unlike earlier clocks that estimate a static biological age number, DunedinPACE measures the pace at which you are currently ageing at the cellular level. A score of 1.0 is average; scores below 1.0 indicate slower ageing. It is particularly valued in longevity research because it is responsive to lifestyle and clinical interventions over a timeframe of three to six months, making it useful for tracking the impact of specific changes rather than just measuring a baseline state.

Can these tests diagnose a disease?

No. Blood biomarker platforms and epigenetic testing services are educational and wellness tools. They are not diagnostic devices, and their results do not constitute a medical diagnosis. Out-of-range results should always be discussed with a qualified healthcare professional who can assess them in the context of your full medical history. This applies to all platforms discussed in this article.

What is the best way to use these tests alongside supplements?

The most effective approach is to establish a baseline before making significant changes to your supplement protocol, then retest after three to six months to assess whether relevant biomarkers have moved into optimal ranges. For example, if you begin a vitamin D programme, testing 25-hydroxyvitamin D levels at baseline and at three months provides objective evidence of whether your dosing is adequate. Similarly, homocysteine testing before and after starting a B vitamin protocol, or monitoring glucose and HbA1c when assessing metabolic interventions, gives you data-supported insight rather than relying solely on subjective experience.

Are these services available outside the United States?

Availability is limited for international users. InsideTracker allows non-US and non-Canadian users to upload blood results from their own healthcare provider for analysis, but cannot provide blood draw services internationally. Function Health and Outlive.bio are currently US-only. TruDiagnostic ships internationally to selected countries for epigenetic testing. International users interested in comprehensive blood panel testing should explore local laboratory services that can order panels equivalent to what these platforms offer, then work with their healthcare provider to interpret results.

How often should I retest?

Most platforms recommend testing every three to six months for active health optimisation. InsideTracker's recommended protocol is the Ultimate test every three months alternating with targeted category tests, though annual testing is also valuable as a minimum. Function Health includes two rounds of testing per year in its membership. TruDiagnostic recommends three-month intervals when actively tracking intervention effects on DunedinPACE. For most general health monitoring purposes, twice-yearly testing provides a meaningful longitudinal picture without excessive cost.

Frequently Asked Questions

1. Lu AT, Quach A, Wilson JG, Reiner AP, Aviv A, Raj K, et al. DNA methylation GrimAge strongly predicts lifespan and healthspan. Aging (Albany NY). 2019;11(2):303–327. View on PubMed ↗
2. McCrory C, Fiorito G, Hernandez B, Polidoro S, O'Halloran AM, Hever A, et al. GrimAge outperforms other epigenetic clocks in the prediction of age-related clinical phenotypes and all-cause mortality. J Gerontol A Biol Sci Med Sci. 2021;76(5):741–749. View on PubMed ↗
3. Mendy A, Mersha TB. Epigenetic age acceleration and mortality risk prediction in US adults. Geroscience. 2025;47(4):6029–6038. View on PubMed ↗
4. Föhr T, Waller K, Viljanen A, Sanchez R, Ollikainen M, Rantanen T, et al. Does the epigenetic clock GrimAge predict mortality independent of genetic influences: an 18 year follow-up study in older female twin pairs. Clin Epigenetics. 2021;13(1):128. View on PubMed ↗
5. Drewelies J, Hueluer G, Duezel S, Vetter VM, Pawelec G, Steinhagen-Thiessen E, et al. Using blood test parameters to define biological age among older adults: association with morbidity and mortality independent of chronological age validated in two separate birth cohorts. Geroscience. 2022;44(6):2685–2699. View on PubMed ↗
6. Bortz J, Guariglia A, Klaric L, Tang D, Ward P, Geer M, et al. Biological age estimation using circulating blood biomarkers. Commun Biol. 2023;6(1):1089. View on PubMed ↗