IGF-1

Insulin-like growth factor 1 (IGF-1) is produced mainly by the liver in response to growth hormone. Because it is far more stable than growth hormone itself, IGF-1 is the practical blood marker of overall GH activity.

IGF-1 supports growth, muscle, and bone, and sits at the center of a genuine longevity trade-off: lower IGF-1 signaling is linked to longevity in animal models, while adequate levels support muscle and bone in aging humans. It is central to diagnosing growth-hormone excess or deficiency.

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   FoundationHealthy AgingThe best place to understand what genuinely preserves healthspan.
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   ConditionSarcopeniaAge-related loss of muscle strength and mass
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   Signal RecordWhey ProteinHigh-Quality Dietary Protein
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   Body SystemHormonesEndocrine signaling that regulates the whole body.

1. Measure it
2. Understand your result
3. See what raises and lowers it
4. Apply evidence-based interventions
5. Recheck on your review cadence

An orientation to how this topic is typically approached — not medical advice.

Very high IGF-1 raises concern for acromegaly (growth-hormone excess); very low values may indicate growth-hormone deficiency, malnutrition, or liver disease. Within the normal range, 'higher' is not simply 'better' given the longevity trade-off.

• Single blood draw (more stable than GH)
• Interpreted with age/sex reference ranges

IGF-1 is a validated marker for diagnosing GH excess and deficiency. Its relationship to aging and cancer risk is an area of genuine scientific nuance, not a simple 'higher is better' story.

• Endocrine Society Clinical Practice Guidelines (acromegaly; GH deficiency)
• Longevity and IGF-1 signaling research literature

Sources are named authoritative guidelines and scientific bodies. Biomarker pages present established clinical context; calibrated evidence verdicts on specific interventions live in the linked Signal Records.