When it comes to men’s health, few topics are as misunderstood as testosterone. Often reduced to stereotypes around muscles or aggression, testosterone is actually the body’s primary male sex hormone – and it affects everything from fertility to mood, energy, and mental clarity.
In our latest episode of The Male Fertility Podcast, Dr Jonathan Andrews, Medical Director at Ted’s Health, joined us to explain exactly what testosterone does, how it changes over time, and what men should know about low levels – including what to do about it.
What Testosterone Actually Does
“Testosterone is responsible for the development and the maintenance of all male characteristics – physical and sexual,”
This goes far beyond what most people expect. Testosterone is what drives the shift from boy to man during puberty, but it continues to shape your body and brain throughout adulthood.
It helps maintain muscle mass and bone density. It fuels your sex drive and supports sperm production. But it also plays a lesser-known role in mental wellbeing – including motivation, focus, energy levels, and even your emotional state.
When testosterone is low, everything from libido to mood, confidence, and concentration can suffer. It’s why a deficiency can feel like you’re just not quite yourself anymore.
The Age Factor: Why Testosterone Declines Over Time
“From the mid-thirties to the forties, testosterone levels tend to decline around 1%, in some cases 2%, per year.”
Unlike menopause in women, testosterone decline in men happens gradually. By your mid-40s, you might have lost 10–20% of your peak levels. The signs can be subtle – less energy, less motivation, more irritability or brain fog – and are often mislabelled as “just getting older.”
But in many cases, these are signs of testosterone deficiency. Left unchecked, it can affect physical, mental, and emotional wellbeing.
Why It’s Not Just Older Men
Low testosterone isn’t just an ageing issue. More and more younger men are presenting with clinical testosterone deficiency due to:
- Poor sleep
- High stress
- Obesity or poor nutrition
- Environmental toxins
- Underlying health conditions
“Don’t assume you’re ‘too young’ to have low testosterone. We’re seeing more and more young men with clinically low levels.”
Modern life is taking its toll. If you’re in your 20s or 30s and feeling run down, unmotivated, or not like yourself – it’s worth getting checked.
The Symptoms You Might Be Missing
Because symptoms develop slowly, they’re often brushed off or misdiagnosed. Dr Andrews outlines the most common signs:
- Low libido or loss of morning erections
- Brain fog and poor concentration
- Persistent fatigue
- Mood changes or irritability
- Difficulty building muscle / increased body fat
- Reduced motivation or drive
These symptoms are often wrongly attributed to stress, lifestyle, or ageing. But testosterone could be the root cause.
Testosterone and Mental Health
One of the most overlooked links is between testosterone and mental health.
“Very commonly, low mood – and I’ll say low mood versus depression – could be the result of low testosterone levels.”
Many men are prescribed antidepressants when their symptoms are actually hormonal. If testosterone is the issue, antidepressants won’t necessarily help. Getting the full picture through proper testing is vital.
Why Lifestyle Changes Don’t Always Work
Improving your lifestyle is always a good idea – but for some men, it’s not enough.
“Even when men adopt ‘testosterone-friendly’ lifestyles, levels can sometimes drop further.”
This can happen during weight loss, or because stress, illness, or other factors override the improvements. The four key pillars that support testosterone are:
- Quality sleep (7–9 hours)
- Stress reduction
- Healthy diet (with plenty of protein and good fats)
- Regular strength-based exercise
But if your testosterone is already low, lifestyle alone might not fix it.
The Right Way to Get Tested
“Proper testosterone diagnosis requires two blood tests, 4–6 weeks apart, taken in the early morning.”
Many men are misdiagnosed due to a single test at the wrong time of day. Testosterone naturally fluctuates, so reliable diagnosis requires repeat testing under the right conditions.
What You Need to Know About TRT
Testosterone Replacement Therapy (TRT) can be life-changing for men with confirmed deficiency – but only when done properly.
“I emphasise the importance of proper medical supervision, licensed medications, and comprehensive health monitoring.”
TRT is not something to start without guidance. You need:
- Two confirmed low testosterone tests
- No improvement from lifestyle changes
- A qualified provider
- A long-term plan for monitoring and safety
And if you’re trying to conceive, there’s a major watch-out…
The Fertility Warning
“If someone is getting steroids elsewhere and they don’t actually need it, one of the biggest risks is to fertility.”
External testosterone tells your body it has enough, so it stops producing its own – and that includes sperm. The signal to make sperm (FSH) drops, which can lead to infertility.
If you’re trying to conceive, it’s crucial to avoid unregulated or unnecessary testosterone use.
Taking Control
Testosterone is about more than muscle. It impacts how you think, feel, function – and how you show up in the world.
“If you’re experiencing symptoms, don’t assume it’s just ageing – get tested by qualified professionals who understand the complexity of hormone health.”
At NeXYs, we know that hormonal health is inseparable from male fertility and overall wellbeing. Whether you’re trying to conceive, feel like something’s off, or just want to understand your body better – testosterone is a key piece of the puzzle.
Listen to the full episode with Dr Andrews on The Male Fertility Podcast