IGF-1: what is a good level?

Written by Steve Fayzulayev. Clinically reviewed by Naomi Fayzulayev, FNP-C, MSN.

Last reviewed 2026-11-09. See our editorial policy and methodology.

Standard reference ranges are age-banded and vary noticeably by lab and sex — a widely used commercial range for the 40s and 50s spans roughly 53 to 298 ng/mL across both sexes combined, with each lab publishing its own narrower band by decade and sex on the report itself.

Longevity-optimised target Scored against your own age band, not one fixed number. Representative midlife band: 120–220 ng/mL optimal, 90–280 ng/mL good, 60–310 ng/mL borderline.

This is the range used by the metabolic dial in the Longevity Score calculator. It is deliberately tighter than the range printed on a standard lab report — the reasoning is below.

What your lab flags vs what the evidence supportsng/mL
Standard
53–298
Optimised
Scored against your own age band, not one fixed number. Representative midlife band: 120–220 ng/mL optimal, 90–280 ng/mL good, 60–310 ng/mL borderline.
0175350

Nothing you type here is sent anywhere, stored, or logged. It never leaves this page.

A result anywhere in the pale band is reported as normal and generates no comment. The brighter band is where risk is lowest. The distance between them is the part a standard report does not tell you.

What IGF-1 actually measures

IGF-1 is produced mainly by the liver in response to growth hormone, and because growth hormone itself pulses unpredictably through the day and is hard to measure directly, IGF-1 — which stays comparatively stable — is used as its practical stand-in on a standard blood draw.

It is scored here as a context marker against your own age band rather than against one universal number, because IGF-1 falls substantially and predictably with age in healthy people — a level that would be low for a 30-year-old can be entirely unremarkable for a 60-year-old.

Why it matters

This is explicitly not a 'higher is always better' marker. Low IGF-1 is linked to reduced muscle mass, slower tissue repair and, in deficiency states, worse metabolic health — but the epidemiological picture at the high end is more complicated: some large cohort studies associate the upper part of the range with higher cancer incidence, which is the opposite direction from most of the markers on this site.

The practical reading most consistent with the evidence is mid-to-upper-normal for your age, not 'maximise it' — which is why this marker is scored with both a floor and a ceiling rather than scored as open-ended.

It sits in the metabolic dial because growth hormone and IGF-1 signalling intersect heavily with insulin sensitivity: the same growth-and-repair axis that builds tissue is tightly linked to how the body partitions fuel.

Why it's on the dashboard

IGF-1 made the panel specifically because it refuses to fit the "more is better" pattern most of this panel follows, and a calculator that pretended otherwise would be giving confidently wrong advice. The evidence for that nuance is unusually direct: in a 22-year study of roughly 100 Ecuadorians with a genetic mutation that keeps IGF-1 very low from birth, Guevara-Aguirre et al. (Science Translational Medicine, 2011) found almost no cancer or diabetes compared with over 1,600 normal-stature relatives — but overall life expectancy was not longer, because deaths from unrelated causes offset the gain. That is the honest lifespan case: pushing IGF-1 low is not a longevity hack, and pushing it high carries its own cancer-incidence signal in other cohorts, which is why this marker is scored with a band rather than a direction. The healthspan case is more straightforward: IGF-1 drives the anabolic signalling behind muscle maintenance and tissue repair, so levels toward the low end of normal track with reduced muscle mass and slower recovery, independent of the cancer question above. See the Metabolic dial for the broader context.

Why this range is stricter than your lab's

A standard lab report answers 'is this typical for my age and sex', which can mean 'typical for an unhealthy population at that age' — commercial reference ranges are built from whoever happened to get tested, which skews toward people with existing symptoms or risk factors.

The optimised band used here is a mid-to-upper-normal target for working-age adults rather than either extreme of the published range, reflecting where the balance of evidence on muscle, metabolic health and cancer risk currently sits — not a push toward the ceiling.

This distinction applies across the whole panel, not just this marker — see optimal versus standard lab ranges for the general case.

What moves IGF-1

Adequate protein intake
IGF-1 production is nutrient-sensitive; chronic under-eating, especially of protein, lowers it independent of age or disease.
Resistance training
Associated with modestly higher IGF-1 in multiple cohorts, consistent with its role in muscle repair signalling.
Sleep
Growth hormone pulses are concentrated in deep sleep; chronic sleep restriction blunts this and can lower IGF-1 over time.
Treating underlying growth-hormone disorders
Both deficiency and excess (acromegaly) are genuine endocrine diagnoses requiring specialist management — an unusually extreme result in either direction, well outside the age-adjusted band, warrants referral rather than a lifestyle-change-and-retest approach.

Educational information, not a treatment plan. Discuss changes to medication or supplementation with a clinician who knows your history.

How fast it responds

Months. IGF-1 reflects sustained growth-hormone signalling and nutritional status rather than anything that moves week to week; a sensible retest interval is six to twelve months unless a specific clinical concern is being tracked. See response times across all markers for how this compares.

What can distort the result

Score IGF-1 against all 8 dials

Frequently asked questions

What is a good IGF-1 level?

The longevity-optimised target used in this calculator is Scored against your own age band, not one fixed number. Representative midlife band: 120–220 ng/mL optimal, 90–280 ng/mL good, 60–310 ng/mL borderline.. Standard reference ranges are age-banded and vary noticeably by lab and sex — a widely used commercial range for the 40s and 50s spans roughly 53 to 298 ng/mL across both sexes combined, with each lab publishing its own narrower band by decade and sex on the report itself.

Why is this target stricter than the range on my lab report?

A standard lab report answers 'is this typical for my age and sex', which can mean 'typical for an unhealthy population at that age' — commercial reference ranges are built from whoever happened to get tested, which skews toward people with existing symptoms or risk factors.

How fast does IGF-1 respond to change?

Months. IGF-1 reflects sustained growth-hormone signalling and nutritional status rather than anything that moves week to week; a sensible retest interval is six to twelve months unless a specific clinical concern is being tracked.

IGF-1 feeds the metabolic dial, and read it alongside Fasting Insulin · HbA1c.

All biomarkers

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.
Ask Us

Choose a question. Answers come from this site, and nothing you open is sent anywhere.

What is a good IGF-1 level?

The longevity-optimised target used in this calculator is Scored against your own age band, not one fixed number. Representative midlife band: 120–220 ng/mL optimal, 90–280 ng/mL good, 60–310 ng/mL borderline.. Standard reference ranges are age-banded and vary noticeably by lab and sex — a widely used commercial range for the 40s and 50s spans roughly 53 to 298 ng/mL across both sexes combined, with each lab publishing its own narrower band by decade and sex on the report itself.

Why is this target stricter than the range on my lab report?

A standard lab report answers 'is this typical for my age and sex', which can mean 'typical for an unhealthy population at that age' — commercial reference ranges are built from whoever happened to get tested, which skews toward people with existing symptoms or risk factors.

How fast does IGF-1 respond to change?

Months. IGF-1 reflects sustained growth-hormone signalling and nutritional status rather than anything that moves week to week; a sensible retest interval is six to twelve months unless a specific clinical concern is being tracked.

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.

All questions