Why Testosterone Matters for Men's Health

Testosterone is the primary male sex hormone, and its influence extends well beyond sexual function. It plays a critical role in muscle mass and strength, bone density, fat distribution, red blood cell production, mood regulation, cognitive function, and energy levels. When testosterone is consistently low, the effects can touch almost every area of a man's health and quality of life.

Understanding what influences your testosterone — and what you can do about it — is a core part of proactive men's health management.

What Is Considered a Normal Testosterone Level?

Testosterone is typically measured through a blood test, with results expressed in nanomoles per litre (nmol/L) or nanograms per decilitre (ng/dL), depending on your country. Reference ranges vary between laboratories and age groups. As a general guide:

  • Normal range (adult men): approximately 10–35 nmol/L (300–1000 ng/dL)
  • Low testosterone (hypogonadism): typically below 10–12 nmol/L (300 ng/dL)

It's important to note that testosterone levels vary throughout the day (highest in the morning) and fluctuate with illness, stress, and sleep. A single test isn't always definitive — your GP will often order at least two morning tests before confirming a diagnosis.

Symptoms of Low Testosterone

Low testosterone (sometimes called "Low T") doesn't always present dramatically. Common symptoms include:

  • Persistent fatigue and low energy
  • Reduced sex drive (libido)
  • Erectile dysfunction
  • Loss of muscle mass or difficulty building muscle
  • Increased body fat, particularly around the abdomen
  • Low mood, depression, or irritability
  • Difficulty concentrating ("brain fog")
  • Reduced bone density (may only become apparent through a scan)

Many of these symptoms overlap with other conditions, which is why blood testing and a clinical assessment are essential before drawing conclusions.

Common Causes of Low Testosterone

Testosterone naturally declines with age — roughly 1–2% per year after the age of 30 for most men. However, several additional factors can accelerate or compound this decline:

  • Obesity — excess body fat increases aromatisation (conversion of testosterone to oestrogen)
  • Chronic sleep deprivation — testosterone is predominantly produced during deep sleep
  • High chronic stress — cortisol suppresses testosterone production
  • Sedentary lifestyle — particularly a lack of resistance training
  • Excessive alcohol consumption
  • Poor nutrition — particularly deficiencies in zinc, vitamin D, and healthy fats
  • Certain medical conditions (hypogonadism, thyroid disorders, type 2 diabetes)

Evidence-Based Ways to Support Testosterone Naturally

Before considering medical intervention, lifestyle changes can make a significant difference for many men:

Resistance Training

Compound strength training — squats, deadlifts, bench press, rows — has a well-established positive effect on testosterone. Prioritise heavy compound movements and progressive overload.

Optimise Sleep

Prioritise 7–9 hours of quality sleep per night. The bulk of daily testosterone production occurs during sleep. Even short-term sleep restriction measurably lowers testosterone levels.

Manage Stress

Chronic stress elevates cortisol, which directly suppresses testosterone. Stress management strategies — exercise, mindfulness, adequate rest, social connection — are not soft recommendations; they have real hormonal consequences.

Support Nutrition

Ensure adequate intake of zinc (found in red meat, shellfish, seeds), vitamin D (sunlight, oily fish, supplementation if deficient), and healthy dietary fats (avocado, olive oil, nuts). Extreme caloric restriction also suppresses testosterone.

Maintain a Healthy Weight

Reducing excess body fat — particularly visceral fat around the abdomen — can meaningfully improve testosterone levels in overweight men.

When to See a Doctor

If you're experiencing persistent symptoms consistent with low testosterone, a GP can arrange a blood test and assess whether medical treatment (such as testosterone replacement therapy) is appropriate. Self-diagnosing and self-treating — including using testosterone boosters sold as supplements — is not advisable without professional guidance. Many over-the-counter "T-boosters" have minimal evidence behind them.

Getting a proper diagnosis is the most important first step.