GGT is usually treated as an alcohol marker and it is a good one — but its association with cardiovascular and metabolic outcomes holds in people who do not drink at all. It behaves as a general readout of oxidative load, which is why it responds to more than the obvious. The calculator's optimal target is under 20 U/L for both sexes; under 15 U/L is excellent.
Target< 15 U/L
The longevity-optimised range used by the organ dial. See what GGT measures for the reasoning.
What to expect, and when
Weeks. The two-to-three-week half-life makes it responsive enough to confirm a change in alcohol intake, which is one of its most practical uses. Changes driven by liver fat take two to three months.
What works, in order of leverage
1. Take a complete break from alcohol
The most direct lever, and the half-life means a genuine four-week break shows clearly. This is as close to a controlled experiment as routine bloods allow.
2. Reduce liver and visceral fat
Fatty liver raises GGT independently of alcohol and is now the most common cause of a mildly raised result in people who drink little.
3. Drink coffee
Consistently associated with lower GGT across large cohorts, with a dose-response relationship.
4. Review enzyme-inducing medication
Anticonvulsants, barbiturates and some other drugs raise GGT through enzyme induction rather than injury. The number is reporting the drug, not damage.
5. Eat cruciferous vegetables
Support glutathione conjugation, which is the pathway GGT sits on. A modest effect, but mechanistically coherent rather than speculative.
6. Check iron status
High ferritin alongside high GGT warrants investigation of iron overload, which is common, genetic and treatable.
What does not work
Worth knowing before spending effort on it.
Assuming a raised GGT means heavy drinking
It is sensitive but not specific. Fatty liver, medication and several conditions raise it in people who drink little or nothing, and the assumption is both wrong and unpleasant.
Liver supplements
Same evidence problem as elsewhere: milk thistle and similar have not shown convincing benefit on meaningful outcomes.
Reading it in isolation
A raised GGT with a normal ALT and ALP points somewhere quite different from all three being raised. The pattern carries the information.
Ignoring a mildly raised value because it is 'only GGT'
Within the normal range, higher GGT predicts diabetes and cardiovascular events. It is among the most informative markers routinely dismissed.
When to involve a clinician
A raised GGT alongside a raised ALP suggests bile duct involvement and needs assessment. Persistent elevation despite genuine change warrants investigation rather than repeated lifestyle attempts.
Not medical advice. These are longevity-optimised reference ranges, which are deliberately stricter than standard clinical "normal" values. A value outside them does not mean you have a disease. Speak to a qualified healthcare professional before changing medication, supplements or training. Full disclaimer.
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What is biological age?
Chronological age counts birthdays. Biological age estimates how old your body appears to be functioning, based on measurable biomarkers. Two people born the same year can differ by a decade or more in vascular stiffness, insulin signalling or cardiorespiratory fitness. Biological age makes that gap explicit — and unlike your birthday, it can move in either direction.
How is the Longevity Score calculated?
Each biomarker you enter is scored against longevity-optimised reference ranges and grouped into one of eight dials. Every dial produces its own biological age, and those are combined using fixed weights into a single composite, then expressed as a Longevity Score from 0 to 100. The weighting reflects how strongly each system predicts healthspan: structural and vascular carry the most, hormonal the least.
Do I need all 53 biomarkers?
No. The short form contains a subset of scoring inputs plus context-only fields, and you can leave any of them blank. It is not a recommendation to obtain tests. Missing values are excluded from the calculation — never treated as zero or as 'normal'. A dial with no scored data is dropped entirely and the remaining weights renormalise.
What can I measure without a blood test?
Some inputs can be measured without bloodwork. Blood pressure needs a home cuff and waist-to-height needs a tape measure. Wearable estimates vary; the floor-based sitting-rising test carries a fall risk and should only be attempted if safe.
Is this an anti-aging calculator? Is it a healthspan calculator?
Both terms describe what this tool does, and which one fits depends on what you are asking. "Anti-aging" is the term most people search, and loosely means anything aimed at slowing or reversing age-related decline — this tool fits that description if you score your dials and act on what you find. "Healthspan calculator" is the more precise term: healthspan is the number of years lived without serious chronic disease or disability, and that cannot be measured directly, so this tool scores eight systems that each function as an early-warning proxy for it. Either way, the method is the same: real biomarkers, published thresholds, no vanity-metric framing.
Why don't you have a quick quiz that skips biomarkers entirely?
Several popular tools ask only about habits — exercise days, sleep hours, smoking, diet quality — and return a single precise-looking age. We looked at the research behind that approach and chose not to build it. Published studies do show real, individually-measured links between specific habits and epigenetic age acceleration, but those effect sizes come from different study populations, different DNA-methylation clocks and different measurement units. Adding them together into one number is not something the underlying research actually supports — it produces a precise-looking result built on an imprecise method. Our dials use direct physiological measurements instead: a real blood pressure reading, a real VO₂ max, a real ApoB value. Several dials score from home-measurable data alone with no quiz-guessing involved — see what you can measure without a blood test, above.
Why are your 'optimal' ranges stricter than my lab's normal range?
Standard reference ranges describe what is common in a general population, which now includes a great deal of metabolic dysfunction. They are tuned to flag disease, not to identify what is optimal for a long healthspan. A fasting insulin of 20 µIU/mL sits inside most labs' normal range and is strongly associated with insulin resistance. This tool uses longevity-optimised thresholds instead, so a flag here means room for optimisation — not a diagnosis.
Why not just upload my labs to ChatGPT?
For understanding a single result, do — a frontier chat model is genuinely good at that, often clearer than most medical sites, and it handles markers no fixed tool covers. The limitation is different from the one most people assume. A language model produces a plausible response rather than a computed one, so the same panel can score differently on different days. That is fine when exploring an idea and disqualifying when measuring change, because you cannot tell how much of a difference is you and how much is the method. Use both: a chat model to understand, a fixed instrument to track.
Is my health data private?
Biomarker values, assessment history and visit-preparation drafts are stored in your browser. The visit draft is separate from assessment exports and share links; copying or printing it can leave a copy outside the browser. There are no user accounts or third-party tracking. We keep anonymous usage totals on our own server, such as how many people reached a results screen on a given day; browsers sending Do Not Track or Global Privacy Control are not counted. Optional lab-report upload and AI coach features send data to Anthropic. Optional retest reminders send an email address, date and reminder label to our service and email provider. See our privacy policy for details.
Is this a medical diagnosis?
No. It is an educational and personal-tracking tool. The estimates are not clinically validated and must not replace evaluation by a qualified healthcare professional. If a result concerns you — particularly kidney markers, blood pressure or ApoB — take it to a doctor rather than acting on it alone.