Hormone Research: Testosterone, Growth Hormone, IGF-1

Testosterone Research: Physiology, Measurement and Evidence

Testosterone is the principal androgen in men and an important hormone in women. Its age-related decline is real but modest — roughly 1% per year after 30 — and much smaller than the decline attributable to obesity and illness. Large trials have clarified both benefits and cardiovascular safety questions.

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Growth Hormone Research: Physiology and the Anti-Ageing Claims

Growth hormone is secreted in pulses from the anterior pituitary and acts largely through hepatic IGF-1. Its decline with age is well documented, but the evidence that raising it in healthy older adults is beneficial is weak, and animal longevity data points in the opposite direction — reduced GH signalling extends lifespan in mice.

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IGF-1 Research: The Growth–Longevity Trade-Off

IGF-1 mediates most of growth hormone's anabolic effects and is one of the most conserved longevity-regulating pathways across species. Human epidemiology shows a U-shaped relationship with mortality: both low and high IGF-1 associate with worse outcomes, which makes simple 'raise it' or 'lower it' framing wrong.

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Metabolic Health: Insulin Sensitivity and How It Is Measured

Metabolic health is usually defined by a cluster of measures: waist circumference, blood pressure, triglycerides, HDL cholesterol and fasting glucose. Insulin resistance underlies most of the cluster, and it develops years before glucose becomes abnormal — which is why fasting glucose alone is a late signal.

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