What Happens When Men Have Low Testosterone?
It’s easy to think of testosterone as just a “male hormone”, something that’s only about sex drive or muscle mass. But in truth, testosterone plays a central role in a man’s overall wellbeing, affecting everything from mood to metabolism, energy to bone health. And when levels drop, whether gradually over time or due to a specific condition, the effects can ripple through many areas of life, often in ways that aren’t immediately obvious.
Not every man with low testosterone will notice dramatic changes. For some, the signs are subtle: a general sense of being more tired than usual, struggling to concentrate, or simply not feeling like themselves anymore. Others might experience more acute symptoms like erectile dysfunction or muscle loss. But either way, the message is the same, testosterone matters, and when it dips too low, things tend to feel... off.
This article takes a deep, realistic look at what happens when testosterone levels fall below healthy levels. It explores the causes, symptoms, diagnosis, treatment options, and broader effects but without reducing it all to clinical checklists. Instead, the goal here is to speak plainly, professionally, and with enough nuance that the topic feels both factual and relatable.
What is Low Testosterone (Male Hypogonadism?)
Low testosterone, medically known as male hypogonadism, occurs when the body doesn't produce enough of the hormone testosterone. This hormone plays a crucial role in male development and health, influencing everything from muscle mass and bone density to mood and sexual function. Testosterone production naturally declines with age, but some men experience a more significant drop, leading to various health issues.
Low Testosterone Causes:
When you hear the term “low testosterone,” it might conjure up images of ageing or midlife crisis clichés but the reality is more complex. Testosterone levels are influenced by a wide range of factors, and understanding why they decline can help clarify how the condition should be approached.
Primary Vs. Secondary Hypogonadism
Low testosterone is technically referred to as male hypogonadism, and it generally falls into two categories:
- Primary hypogonadism: This is when the problem originates in the testicles themselves. The testicles are responsible for producing testosterone, so any direct damage or abnormality can reduce output. Genetic conditions such as Klinefelter syndrome, injury (especially trauma involving the groin), or infections like mumps orchitis fall under this type.
- Secondary hypogonadism: Here, the issue starts higher up in the hypothalamus or the pituitary gland - both of which regulate hormone signaling in the body. If they’re not sending the right signals to the testicles, testosterone production stalls. This type can be triggered by pituitary tumours, chronic illnesses, or even certain medications, such as opioids and glucocorticoids.
Lifestyle and Environmental Factors
Low testosterone isn’t always rooted in something as defined as genetic syndromes or organ failure. In many cases, it’s part of a more subtle, systemic issue. A growing body of research points to lifestyle as a key player:
- Obesity: Fat cells actually convert testosterone into oestrogen, so the more excess fat a man carries, particularly around the midsection, the greater the hormonal disruption.
- Chronic stress: Elevated cortisol levels can suppress testosterone production. This isn’t just about emotional burnout even the low-grade, everyday kind of stress can have physiological consequences.
- Sleep deprivation: Testosterone is largely produced during deep sleep. A study published in the Journal of the American Medical Association found that even one week of sleep restriction in healthy young men reduced testosterone levels by up to 15%.
- Poor diet and lack of exercise: Sedentary lifestyles, nutrient deficiencies, and excess sugar intake also contribute to hormonal imbalance.
And of course, there’s the natural age-related decline, often referred to as andropause. After the age of 30, testosterone levels typically drop by about 1% per year. But that decline isn’t uniform, and some men experience far sharper decreases than others.
In short, there’s no single cause of low testosterone. For some, it’s medical. For others, it’s behavioural. And in many cases, it’s both - a mix of ageing biology and modern lifestyle.
Recognising the Symptoms
Testosterone isn’t a hormone that quietly fades into the background. When it drops, things change, sometimes subtly, other times dramatically. And because its effects are so widespread, the symptoms of low testosterone can show up in ways that aren’t always easy to pin down.
Physical Symptoms
These are often the most noticeable, and for many men, the first signs that something isn’t quite right:
- Reduced libido: This is perhaps the most well-known symptom, but it’s worth emphasising that it’s not about a complete loss of sexual desire. It may simply mean a lower interest than usual, or feeling “disconnected” from intimacy.
- Erectile dysfunction: Testosterone plays a role in stimulating receptors in the brain that trigger arousal. When levels are low, erections can become less frequent, less firm, or harder to maintain even when other aspects of sexual health appear normal. Read more: Helping Your Partner With Erectile Dysfunction
- Fatigue: Not just the kind of tiredness that follows a poor night’s sleep, but a persistent, energy-sapping sense of exhaustion that doesn’t lift with rest.
- Muscle loss and weight gain: Testosterone supports lean muscle mass. When it falls, muscle tone declines and body fat, especially abdominal fat increases.
- Reduced bone density: Long-term testosterone deficiency can lead to weakened bones, increasing the risk of fractures and osteoporosis.
Emotional and Cognitive Changes
Low testosterone also affects the brain, a fact that often gets less attention. It’s linked to:
- Mood swings or depression
- Irritability
- Anxiety
- Low motivation or drive
- Difficulty concentrating, something described as brain fog
There’s something quietly frustrating about these symptoms. They don’t announce themselves loudly. Instead, they chip away at your mental clarity or emotional resilience, making tasks feel more difficult, and life generally feel heavier.
Testing and Diagnosis
Getting diagnosed with low testosterone isn’t just a matter of describing symptoms. It requires a combination of clear clinical suspicion and carefully timed blood tests. And yes, timing matters, testosterone levels fluctuate throughout the day.
The Testing Process
- Initial blood tests: These are usually done early in the morning (between 7 and 10am) when testosterone levels peak. A level below 300 nanograms per decilitre (ng/dL) is often considered low, but some doctors use slightly different reference ranges based on lab protocols.
- Total vs free testosterone: Total testosterone is measured first. If it’s low or borderline, a free testosterone test may be ordered, this checks the amount of testosterone available for use in the body, which can sometimes be disproportionately low even if total levels seem adequate.
- Additional hormone tests: To determine whether the issue lies in the testicles or higher up in the hormone signalling chain, doctors may also check levels of LH and FSH. These help distinguish between primary and secondary hypogonadism.
- Other relevant tests: Depending on symptoms, a doctor might order tests for prolactin (which can be high in pituitary tumours), thyroid function, or imaging scans if a pituitary issue is suspected.
It’s a process that can take a bit of time, particularly if multiple tests are needed to confirm consistent low levels. But the goal is clarity, not just confirming that testosterone is low, but understanding why.
When to See a Doctor
If you’ve been noticing symptoms like persistent fatigue, low libido, or mood changes for more than a few months, it’s worth having a conversation with your GP. Many men put off this kind of visit out of embarrassment or the assumption that “it’s just part of getting older.” But age alone isn’t an excuse to feel unwell.
Low testosterone is a medical condition. And like any condition, it benefits from early attention so it's always best to get the ball rolling.
Living With Low Testosterone
Once diagnosed, the next question is usually: what now? The answer isn’t always straightforward. Treatment depends not only on how low your testosterone levels are, but also on how much those levels are affecting your quality of life. For some men, medical treatment is essential. For others, lifestyle changes may be enough to tip the balance.
Testosterone Replacement Therapy (TRT)
TRT is the most direct form of treatment. It works by supplementing the body’s natural testosterone, helping to restore levels and alleviate symptoms. But as with any hormone therapy, it’s not without nuance.
Forms of TRT include:
- Injections: Often administered every one to two weeks. These can cause fluctuations in hormone levels, a bit of a “rollercoaster” effect that some men find hard to manage.
- Gels or creams: Applied daily to the skin. These offer more stable hormone delivery but require careful application (and you must avoid skin contact with others after use).
- Patches: Worn on the body or scrotum; they release testosterone slowly throughout the day.
- Pellets: Implanted under the skin and last several months, a more hands-off approach, though they require minor outpatient procedures.
Risks and Considerations
TRT isn't a one-size-fits-all solution, and it’s not suitable for every man. In particular, it may not be recommended for those who are trying to conceive (testosterone can reduce sperm count), or for men with prostate or breast cancer. Other possible side effects include:
- Fluid retention
- Sleep apnoea exacerbation
- Acne or oily skin
- Increased red blood cell count (which can raise stroke risk if not monitored)
- Potential cardiovascular risks, though studies have shown conflicting results
That’s why any man starting TRT should be regularly monitored with blood tests every few months initially, to ensure hormone levels remain in a healthy range and to check for side effects.
Lifestyle Changes
For men with borderline testosterone levels or those who aren’t good candidates for TRT, lifestyle changes can make a meaningful difference. Even for men on hormone therapy, these strategies can amplify results:
- Lose excess weight: Studies show that losing just 5–10% of body fat can significantly boost testosterone levels.
- Strength training: Lifting weights, in particular, stimulates natural testosterone production.
- Improve sleep hygiene: Aiming for 7–9 hours of good-quality sleep each night supports hormone regulation.
- Reduce alcohol intake: Chronic drinking suppresses testosterone, especially in large quantities.
- Manage stress: High cortisol levels interfere with testosterone. Mindfulness, breathing exercises, or simply taking time to unwind each day can help.
These aren’t quick fixes, they take commitment. But they’re also broader investments in your long-term health, and the benefits extend far beyond hormone balance.
The Long-Term Impact
Low testosterone isn’t just about feeling tired or disinterested in sex. Left untreated, it can increase the risk of more serious health problems, some of which unfold slowly, beneath the surface.
Bone Health and Osteoporosis
Testosterone helps maintain bone mineral density. Men with chronic low testosterone are at higher risk of developing osteoporosis, a condition more commonly associated with women but no less serious in men. Fragile bones mean higher chances of fractures from minor accidents or falls.
A 2022 paper in The Journal of Clinical Endocrinology & Metabolism highlighted that men with testosterone deficiency had significantly reduced bone mass and higher fracture risk, even at relatively young ages.
Metabolic Syndrome and Type 2 Diabetes
There’s a strong link between low testosterone and metabolic syndrome, a cluster of conditions that includes high blood pressure, abdominal obesity, high cholesterol, and insulin resistance. Together, these dramatically increase the risk of developing type 2 diabetes and heart disease.
Interestingly, this relationship appears to be two-way: men with diabetes often have low testosterone, and men with low testosterone are at higher risk of developing diabetes. It’s a complex interplay, and one that’s still being researched, but the connection is undeniable.
Cognitive Decline
Some studies suggest that testosterone plays a role in maintaining cognitive function, particularly spatial ability and memory. While the evidence is still emerging, there’s growing interest in whether low testosterone contributes to age-related cognitive decline or even dementia risk.
A study published in Neurology (2015) found that older men with low free testosterone were more likely to experience cognitive decline over a five-year period. While not conclusive, it’s a clue worth noting.
Mental Health and Quality of Life
The psychological effects of low testosterone are often underappreciated. Men may feel withdrawn, demotivated, or generally “flat.” This isn’t just moodiness, it’s a hormonal issue with real emotional weight.
Some men report a marked improvement in wellbeing after starting treatment, even when physical symptoms haven’t changed significantly. That highlights an important truth: hormonal health isn’t just about numbers on a chart. It’s about how you feel in your body and your mind.
A Hormone Worth Paying Attention To
Testosterone might not be something you think about often, at least not until it starts to decline. But it’s a key part of male health, influencing everything from physical strength and sexual performance to energy, mental focus, and emotional balance. When testosterone is low, life feels different. Blunted. Diminished, somehow even if it’s hard to put into words.
The good news is that low testosterone is treatable. Whether through medical therapy, lifestyle adjustments, or a combination of both, many men are able to restore their hormone levels and start feeling like themselves again. But that can only happen once the issue is recognised and, crucially, taken seriously.
If you’ve been feeling persistently tired, distracted, down, or just not quite “you,” it’s worth checking your levels. Low testosterone isn’t rare, and it’s not something to ignore. It’s simply a part of the broader story of male health, one that’s too important to leave untold.
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