Testosterone (Male)
| Clinical | Optimal | |
|---|---|---|
| Male | 8.6 - 29.0 nmol/L | 12–31 nmol/L (optimal: 15–25 nmol/L) |
| Female | 0.3 - 1.7 nmol/L | N/A (see female testosterone) |
What is Testosterone (Male)?
Testosterone is the primary male sex hormone, produced mainly in the testes with small amounts from the adrenal glands. Your blood test measures total testosterone — the combined amount of testosterone bound to proteins (SHBG and albumin) and the small fraction circulating freely.
Testosterone drives male sexual development during puberty and maintains masculine characteristics throughout life: muscle mass, bone density, body hair, deepened voice, and sperm production. But its role extends far beyond reproduction — it influences energy levels, mood, cognitive function, red blood cell production, and fat distribution.
Testosterone levels follow a daily rhythm, peaking in the early morning and declining through the day. This is why blood tests should ideally be taken before 10am for the most accurate reading.
Why Testosterone (Male) Matters for Your Health
Testosterone is fundamental to male health and vitality. It supports lean muscle maintenance, bone strength, cardiovascular health, mental sharpness, and emotional resilience. Even modest declines can significantly affect quality of life.
Male testosterone levels naturally decline by approximately 1–2% per year after age 30. However, modern lifestyle factors — poor sleep, chronic stress, excess body fat, sedentary behaviour, and processed diets — can accelerate this decline beyond what ageing alone would cause.
From a longevity perspective, maintaining healthy testosterone levels supports metabolic health, cardiovascular function, bone density, and cognitive performance as men age. It is one of the most impactful hormones for male health span — the number of years lived in good health.
Testosterone (Male)& Your Wearable Data
Testosterone is the primary male sex hormone, essential for muscle mass, bone density, mood, libido, and cardiovascular health. Wearable data provides excellent context for testosterone-related changes. Low testosterone manifests as reduced exercise performance, declining strength and VO2 max, increased body fat, and impaired recovery — all trackable through your wearable's fitness metrics.
Exercise type and intensity directly influence testosterone levels. Wearable data showing heavy resistance training and high-intensity intervals correlates with acute testosterone spikes, while excessive endurance training without adequate recovery can suppress testosterone. The ratio of training load to recovery, visible in your wearable's HRV trends and readiness scores, predicts whether your exercise pattern is supporting or suppressing testosterone production.
Sleep is the most powerful modifiable factor for testosterone. Most testosterone is produced during deep sleep, and wearable data consistently shows that men sleeping fewer than 6 hours have significantly lower testosterone. Your wearable's sleep duration, deep sleep percentage, and sleep consistency metrics directly relate to testosterone production. Optimising sleep as tracked by your wearable is often the most effective first step for improving testosterone levels.
What High Testosterone (Male) May Suggest
Naturally high testosterone within the reference range is generally a positive sign, reflecting good health, fitness, and hormonal balance. Very few men have naturally excessive testosterone levels.
Elevated testosterone above the reference range is almost always caused by exogenous testosterone use — testosterone replacement therapy (TRT) or anabolic steroids. In rare cases, testicular or adrenal tumours can produce excess testosterone.
Symptoms of excessively high testosterone include acne, oily skin, aggression, sleep disturbances, elevated red blood cell count (polycythaemia), and potential cardiovascular strain. If you are on TRT and testosterone is above range, your dose may need adjustment.
What Low Testosterone (Male) May Suggest
Low testosterone (hypogonadism, below 12 nmol/L on a morning blood test) affects an estimated 2–6% of men and becomes more common with age. However, many men with symptoms have levels in the 'low-normal' range (12–15 nmol/L) where optimisation can still help.
Common causes of low testosterone include obesity (excess body fat converts testosterone to oestrogen), chronic stress (cortisol suppresses testosterone production), poor sleep (testosterone is produced primarily during deep sleep), excessive alcohol consumption, chronic illness, certain medications, and primary testicular problems.
Symptoms include reduced libido, erectile difficulties, fatigue, low mood, difficulty building or maintaining muscle, increased body fat (particularly around the abdomen), brain fog, and reduced motivation. If lifestyle optimisation does not improve levels, your GP may consider further investigation or referral.
How to Optimise Your Testosterone (Male)
Food
Eat sufficient healthy fats (olive oil, avocado, nuts, oily fish) — testosterone is synthesised from cholesterol, and very low-fat diets can reduce production. Include zinc-rich foods (oysters, red meat, pumpkin seeds) and magnesium-rich foods (dark chocolate, spinach, almonds). Ensure adequate vitamin D from oily fish and eggs. Minimise processed foods, excess sugar, and excessive alcohol, all of which suppress testosterone. Cruciferous vegetables (broccoli, cauliflower) support healthy oestrogen metabolism.
Lifestyle
Prioritise 7–9 hours of quality sleep — testosterone production peaks during deep sleep, and even partial sleep deprivation dramatically lowers levels. Resistance training (compound lifts: squats, deadlifts, bench press) is one of the most powerful natural testosterone boosters. Maintain a healthy body composition — losing excess body fat directly increases testosterone. Manage chronic stress through breathwork, cold exposure, or meditation. Limit alcohol to moderate levels. Avoid endocrine disruptors (BPA in plastics, parabens in personal care products).
Supplements
Vitamin D3 (2,000–4,000 IU daily if deficient) has been shown to support testosterone levels. Zinc (25–30 mg daily if deficient) is essential for testosterone synthesis. Magnesium (200–400 mg glycinate) supports testosterone, particularly in active men. Ashwagandha (300–600 mg KSM-66 extract) has clinical evidence for modestly improving testosterone and reducing cortisol.
When to Speak to Your GP
See your GP if testosterone is below 12 nmol/L on two separate morning tests, or if you have significant symptoms (loss of libido, erectile dysfunction, extreme fatigue) at any level. Your GP may request LH and FSH to determine whether the issue is testicular (primary) or pituitary (secondary). Urgent referral is warranted if testosterone is very low (below 8 nmol/L) with significant symptoms, or if a testicular or pituitary abnormality is suspected.
References
- NHS. Low sex drive (loss of libido) — Overview. Updated 2024. nhs.uk
- NICE. Testosterone deficiency in men — Clinical Knowledge Summaries. cks.nice.org.uk
- BSSM. Hackett G, et al. British Society for Sexual Medicine guidelines on adult testosterone deficiency. J Sex Med. 2017;14(12):1504-1523. pubmed.ncbi.nlm.nih.gov
- NEJM. Snyder PJ, et al. Effects of testosterone treatment in older men. N Engl J Med. 2016;374(7):611-624. pubmed.ncbi.nlm.nih.gov
- Endocrine Society. Bhasin S, et al. Testosterone therapy in men with hypogonadism. J Clin Endocrinol Metab. 2018;103(5):1715-1744. pubmed.ncbi.nlm.nih.gov
Medical Disclaimer— This content is for general educational and informational purposes only. It does not constitute medical advice, diagnosis, or treatment. Omniwo Ltd is a wellness information service and is not a medical device, clinical laboratory, or regulated healthcare provider under MHRA guidelines. The “optimal ranges” presented on this page are based on published clinical guidelines (WHO, NICE, NHS) and peer-reviewed research; they represent functional wellness targets and may differ from standard laboratory reference ranges. Individual results should always be interpreted by a qualified healthcare professional (such as your GP) who understands your full medical history. Do not start, stop, or change any medication or supplement based solely on this information. If you are experiencing symptoms, seek medical attention promptly.