What is Testosterone?

Testosterone is the primary androgen (male sex hormone) produced mainly in the testes (and in smaller amounts by the ovaries/adrenals) that circulates in the bloodstream and drives multiple processes: muscle-growth and maintenance, bone integrity, fat metabolism, and influence on mood and energy. In men, total testosterone is typically measured in nmol/L and is one of the key biomarkers reflecting androgen status.

Why does it matter for long-term health and wellbeing?

From a preventive and performance-oriented viewpoint, maintaining healthy testosterone levels helps preserve lean muscle mass, supports metabolic efficiency (such as better fat-burning and insulin sensitivity) and helps sustain strength and vitality as we age. Research highlights how muscle mass and strength are closely tied to overall health outcomes and longevity, and testosterone plays a part in those adaptive responses.

Monitoring testosterone gives you a window into your hormonal health and how it may be responding to lifestyle factors like sleep, nutrition, exercise and stress—so you can optimise rather than just react.

What’s an optimal level of Testosterone?

• Laboratory reference range in Australian adult males: approximately 8.3 to 29 nmol/L.
• At present there is no universally agreed “optimal” range above and beyond the standard reference, as optimal depends on age, health status and individual goals.
• For proactive optimisation (rather than disease screening) you might aim for the mid-to-upper part of the reference range, while recognising individual variation and working with trends over time.

(Note: for women, total testosterone reference ranges are much lower and different guidelines apply.)

What influences Testosterone levels?

Many lifestyle, environmental and biological factors impact testosterone levels. Some key influences include:

• Age: Testosterone tends to peak in early adulthood and gradually declines with age.
• Body composition and fat-mass: Higher levels of fat, especially visceral fat, and lower lean mass are associated with lower testosterone.
• Exercise and muscle-building: Strength and resistance training help support healthy testosterone responses and lean mass.
• Nutrition: Dietary pattern, calorie balance and macro-nutrition (especially protein and healthy fats) influence hormone production.
• Sleep, stress and recovery: Poor sleep quality, high chronic stress and inadequate recovery can suppress testosterone.
• Binding-proteins: Sex Hormone Binding Globulin (SHBG) and albumin affect how much testosterone is free vs bound and thus biologically active.

What does it mean if Testosterone is outside the optimal range?

• If measured testosterone falls near the lower end of the laboratory reference—or below your individual trend—it may signal that hormonal support for muscle, metabolism and energy is less optimal. This doesn’t necessarily imply a disease state, but it does offer a valuable insight for lifestyle optimisation.
• If testosterone is at the higher end of the range (or elevated beyond the expected range for your age and health status), it may reflect stronger androgenic drive, but also calls for awareness of balance (e.g., how it interacts with recovery, sleep, and other hormones).

In both cases, tracking over time is key: one single value is less actionable than your direction of change and response to lifestyle interventions.

How can I support healthy Testosterone levels?

Here are evidence-based lifestyle strategies to help support testosterone levels:

• Prioritise resistance and strength training to preserve and build lean muscle mass, which in turn supports testosterone signalling.
• Ensure sufficient dietary protein and healthy fats (including sources of saturated and mono-/poly-unsaturated fats) as raw materials for hormone production.
• Maintain healthy body composition—reducing excess adiposity and supporting lean mass helps hormone regulation.
• Optimise sleep quantity and quality: aim for consistent, adequate sleep and minimise disruptions.
• Manage stress and recovery: chronic stress can drive hormonal imbalance; include recovery routines, breaks and relaxation.
• Monitor your trends: regular testing lets you see how your testosterone responds to your habits so you can fine-tune.

This information is provided for general health and wellness purposes only and does not replace medical advice.

References

1. Handelsman, D. J. et al. Endocrine Society of Australia position statement on male hypogonadism: The reference interval in young men is 7.4–28.0 nmol/L. Med J Aust. 205(4). 
2. Royal College of Pathologists of Australasia (RCPA). Testosterone – Total. Reference intervals and assay notes.
3. Gharahdaghi, N., et al. Links Between Testosterone, Oestrogen and Growth Hormone: implications for skeletal muscle mass regulation. Front Physiol. 2020;11:621226.
4. Green, D. J., et al. Comparing the impacts of testosterone and exercise on lean body mass in older adults. J Gerontol A Biol Sci 2023.