Hormone optimisation for Australian men over 35: peptides, blood work, and the evidence-based approach

Testosterone declines at approximately 1–2% per year from the age of 30, with significant individual variation. By age 50, many men have testosterone levels in a range that would have been considered low by their 25-year-old standards — yet still within the broad laboratory reference range. This is one of the central problems with hormone health in conventional medicine: reference ranges are calibrated to the average population, not to the functional level at which an individual feels and performs optimally. Growth hormone declines more steeply — approximately 14% per decade from the mid-twenties — with meaningful consequences for body composition, sleep architecture, cognitive function, and recovery capacity. The practical effect for many men in their 40s is a cluster of symptoms: increased body fat (particularly visceral), reduced muscle mass despite consistent training, poor sleep, reduced mental sharpness, and lower energy — each of which has a hormonal component that is addressable.

Total testosterone is the standard measure but is frequently insufficient for clinical decision-making. The more useful markers are free testosterone (the biologically active fraction not bound to SHBG or albumin) and SHBG (sex hormone binding globulin — elevated SHBG binds testosterone and reduces free availability). A man with total testosterone of 20 nmol/L but high SHBG may have less free testosterone than a man with total testosterone of 15 nmol/L and low SHBG. The typical laboratory reference range for total testosterone in Australia is 10–35 nmol/L — a range so wide that significant functional decline can occur without technically leaving it. Practitioners who use optimal ranges rather than deficiency ranges — typically targeting 18–30 nmol/L total testosterone and above 400 pmol/L free testosterone — provide more clinically relevant guidance. Equally important: LH (luteinising hormone) and FSH levels indicate whether low testosterone is primary (testicular) or secondary (pituitary/hypothalamic) — a distinction that determines the appropriate intervention.

Growth hormone in adult men is primarily significant not for muscle growth per se (as it is in adolescence) but for body composition maintenance, sleep quality, metabolic health, and tissue repair. The progressive decline in GH pulsatility — particularly the reduction in peak sleep-phase GH release — contributes substantially to the body composition changes men experience in their 40s: increased visceral fat accumulation, reduced lean mass maintenance, impaired recovery from exercise, and reduced collagen synthesis. Ipamorelin/CJC-1295, administered before sleep, restores physiological GH pulsatility without providing exogenous GH. The feedback mechanisms of the pituitary remain intact — the peptides stimulate the body's own GH production rather than bypassing the system. This is the most common peptide prescription for men seeking hormone optimisation in Australia, and the evidence base for its safety and efficacy is the strongest of any peptide in the category.

Peter Attia's framework from Outlive identifies exercise — specifically VO2 max and strength — as the single most powerful predictor of longevity and the metric most correlated with all-cause mortality reduction. Testosterone levels are meaningfully influenced by sleep quality, body fat percentage, zinc status, vitamin D, stress levels, and alcohol consumption. Men who pursue peptide-based hormone optimisation without addressing these foundational variables will see marginal results. Specifically: visceral body fat is hormonally active and produces aromatase (the enzyme that converts testosterone to oestrogen). Reducing visceral fat through dietary changes and exercise is one of the most effective ways to improve free testosterone levels. This is not an argument against peptide therapy — it is an argument for sequencing. The lifestyle foundation should be established before peptide-based optimisation is layered on top.

A comprehensive hormone optimisation consultation should involve extensive blood work before any prescription is written. The minimum panel for men seeking hormone optimisation should include: total testosterone, free testosterone, SHBG, LH, FSH, IGF-1, DHEA-S, oestradiol, prolactin, TSH (thyroid), fasting glucose, HbA1c, lipid panel with ApoB, high-sensitivity CRP, full blood count, and vitamin D. This panel provides a complete picture of the hormonal environment and identifies the specific components that are out of optimal range. A prescriber who writes a prescription for Ipamorelin/CJC-1295 after a 10-minute consultation without blood work is not practising evidence-based medicine. The data-driven approach also provides a baseline against which to measure the effect of any intervention — without baseline data, it is impossible to know whether the protocol is working.

Testosterone replacement therapy (TRT) and GH secretagogue therapy address different aspects of the male hormone decline picture and are not mutually exclusive. TRT directly replaces testosterone — appropriate for men with diagnosed hypogonadism (typically total testosterone below 8–10 nmol/L in Australia). GH secretagogues address the GH axis — appropriate for virtually all men over 40 with intact pituitary function. For men with low-normal testosterone (12–18 nmol/L with symptoms), the appropriate intervention is less clear-cut — some respond well to lifestyle optimisation and targeted supplementation (zinc, vitamin D, ashwagandha); others require TRT. Peptide-based GH optimisation is a lower-risk, non-hormonal approach that can meaningfully improve body composition and wellbeing without the suppression of endogenous testosterone production that TRT causes. For men who are not yet at the threshold for TRT, a GH secretagogue protocol is often the appropriate first intervention.