Written and medically reviewed by Dr. Daniel Chong. Last reviewed 2026-09-01. 10 min read
The consultation usually opens the same way.
He is somewhere in his forties. He is tired in a way that sleep does not fix. He has gained weight around the middle without changing much. The gym is producing less than it used to. His mood is flatter, his motivation is lower, and his interest in things he used to enjoy has quietly declined. He has read a great deal online, he has arrived at a conclusion, and he would like his testosterone checked.
I will check it, and we will do it properly.
But I want to explain why, in my experience, testosterone turns out to be the answer considerably less often than men expect, and why the things that turn out to be the answer instead are usually more treatable and frequently more important.
The symptoms he has described are real. They are also almost entirely non-specific, meaning they are produced by a long list of conditions, several of which are common in men of that age in this country and none of which improve with testosterone.
Nine things that cause these symptoms more often than low testosterone
1. Obstructive sleep apnoea
If I could investigate one thing in a tired man in his forties with a thickened waist, it would be this.
Sleep apnoea is substantially underdiagnosed here. It produces exactly the symptom picture described above: unrefreshing sleep, daytime fatigue, low mood, poor concentration, reduced drive. It also raises blood pressure and is closely tied to central weight gain.
Two things make it particularly relevant to this conversation. Untreated sleep apnoea directly lowers testosterone, so it can be the cause of a low reading rather than a coincidental finding. And testosterone therapy can worsen untreated sleep apnoea, which means getting the order wrong is not neutral.
Snoring, witnessed pauses in breathing, waking unrefreshed, needing to urinate at night, and a larger neck circumference are the clues. Ask your partner, who usually knows.
2. Visceral fat and insulin resistance
Fat tissue converts testosterone into oestradiol, and central obesity lowers both total and free testosterone. So in a man with a significant waist, low testosterone is frequently a consequence rather than a cause.
This matters practically, because weight loss raises testosterone in men with obesity. Treating the cause addresses the reading, and it addresses a great deal else besides.
3. Depression
The symptom list for depression in men and the symptom list marketed as low testosterone overlap almost entirely. Fatigue, low mood, reduced motivation, poor concentration and disturbed sleep.
Men in this country are not especially likely to raise mood with a doctor, and a testosterone test is a more comfortable way to open the conversation than the alternative. I understand that, and I would rather we discussed it directly. Untreated depression does not improve with a hormone that was never the problem.
4. Alcohol
Regular drinking lowers testosterone, fragments sleep, adds energy without nutrition and drives visceral fat. It is often the single largest modifiable factor in the room and the one least likely to be volunteered.
5. Thyroid disease
Fatigue, weight change, mood change and cognitive slowing. Straightforward to test and straightforward to treat.
6. Iron deficiency or anaemia
Adult men should not be iron deficient. If a man is, the question is where the iron went, and that usually means investigating the gastrointestinal tract. This is one of the genuinely important findings that turns up when a fatigue workup is done properly rather than narrowly.
7. Medication
Several common medications lower testosterone, including opioid painkillers, which are a well-recognised and frequently missed cause, along with corticosteroids and several others. A full medication and supplement review is part of any assessment worth having.
8. Diabetes and prediabetes
Both are strongly associated with low testosterone and both are common here. Fatigue is a presenting symptom of undiagnosed diabetes often enough that it should be excluded early.
9. Simply not sleeping enough, or training badly
Chronic short sleep lowers testosterone measurably. So does sustained overtraining without recovery, and so does chronic stress. These are unglamorous answers and they are frequently the right ones.
How to test testosterone properly
If, after all of that, testing is appropriate, it needs doing correctly. Testosterone is one of the more commonly mis-measured results in medicine.
Two separate samples, both in the morning, both fasting. Testosterone follows a strong daily rhythm and is highest in the early morning. An afternoon sample can be substantially lower and means very little. One low result is not a diagnosis; it needs confirming on a second occasion.
Total testosterone alongside SHBG, the protein that binds most of the testosterone in your blood, so that free testosterone can be calculated. This matters because SHBG is altered by obesity, by age, by thyroid function and by liver disease, meaning a total testosterone figure alone can be misleading in either direction.
If the result is genuinely low, LH and FSH, which distinguish a problem in the testes from a problem in the pituitary or hypothalamus. These have entirely different implications.
Prolactin, where the pattern suggests a pituitary cause, because a prolactin-secreting pituitary tumour is a treatable cause that must not be missed.
Not during an acute illness, which lowers testosterone temporarily.
And crucially, symptoms plus consistently low levels. A borderline number in a man without symptoms is not a diagnosis, and neither is a symptomatic man with normal levels. Both situations are common, and both are frequently treated as though they were hypogonadism.
Establishing why testosterone is low is not an optional preliminary. Prescribing without investigating can leave a treatable underlying cause undiagnosed.
What testosterone therapy does and does not do
For men with genuine, confirmed hypogonadism, treatment has a real place. I am not against it. I am against it being the first answer to a question nobody has properly asked.
What the evidence supports: modest improvement in mood, and gains in lean mass and bone density.
On cardiovascular safety, the TRAVERSE trial randomised over five thousand middle-aged and older men with hypogonadism and elevated cardiovascular risk and found testosterone non-inferior to placebo for major adverse cardiac events. That addressed a long-standing concern. The same trial found higher rates of pulmonary embolism, atrial fibrillation and acute kidney injury in the testosterone group. Non-inferiority is reassurance, not benefit.
What it does not do. It does not reliably resolve fatigue in men whose levels were never low. It has not been shown to extend life. And it does not fix sleep apnoea, depression, alcohol intake or visceral fat, all of which will still be there afterwards.
The risks that matter in practice. A rise in haematocrit is the most common adverse effect, which thickens the blood and requires monitoring rather than being optional. Testosterone suppresses sperm production and can substantially impair fertility, sometimes persistently, so any man who might want children needs to know this before he starts. Untreated sleep apnoea can worsen. And prostate monitoring is part of the follow-up.
What every man over forty should actually be measuring
Testosterone is not on this list, and that is deliberate.
Blood pressure. The single highest-value measurement available and the one most often skipped by men who feel fine.
ApoB, and lipoprotein(a) once in a lifetime. ApoB counts the atherogenic particles rather than the cholesterol inside them. Lipoprotein(a) is genetically fixed, measured once, never repeated, and if elevated it changes how aggressively everything else should be managed.
HbA1c and fasting insulin. Insulin resistance is detectable years before glucose starts to drift, and it is the mechanism underneath most of what goes wrong in this decade.
Waist circumference and body composition, with lean mass reported separately. Not weight.
Liver assessment, since fatty liver disease is common here, silent, and closely tied to the same metabolic picture.
Grip strength and cardiorespiratory fitness. Cheap, quick, and among the more strongly evidenced predictors of long-term outcomes available. Neither appears in a standard package.
Sleep, assessed honestly, including screening for apnoea where the picture fits.
And mood, asked about directly rather than left to come up on its own.
The symptoms men leave until last
Some changes are harder to raise in a consultation than others, and men routinely leave those until the end of the appointment or omit them entirely.
It is worth mentioning them, and not for the reason most men assume. The smallest arteries in the body show the effects of endothelial dysfunction earlier than the larger coronary arteries do, which means changes in circulation can appear years before anything shows up in the heart. Symptoms that feel local and embarrassing are frequently vascular, and vascular symptoms are early information rather than a separate problem.
So the appropriate response is a cardiovascular assessment: blood pressure, lipids including ApoB, glucose, waist, smoking status and a formal risk calculation.
Please mention whatever you were going to leave out. It is usually the most useful thing you will say.
The short version
The symptoms that send men to ask about testosterone are real and worth investigating. They are also non-specific, and in men in their forties they are more commonly explained by sleep apnoea, visceral fat, alcohol, depression, thyroid disease, iron deficiency or medication than by a hormone deficiency.
Test testosterone by all means, but test it properly, twice, in the morning, with SHBG, and alongside everything else. And if it is low, find out why before deciding what to do about it.
The things most worth measuring in this decade are blood pressure, ApoB, lipoprotein(a) once, HbA1c and insulin, waist and body composition, grip strength and fitness. None of them is a hormone.
Book an assessment
A first appointment covers the full picture rather than a single hormone: sleep, mood, metabolic markers, body composition, functional testing and a medication review, with hormonal assessment where it is indicated.
Book a consultation with the HAYAT Longevity clinical team.
Frequently asked questions
If you have persistent symptoms, yes, as part of a broader assessment rather than on its own. Testing testosterone in isolation, without checking sleep, mood, thyroid, iron, glucose and medications, produces a number without a context.
Early morning and fasting, and on two separate occasions before any diagnosis is made. Afternoon samples are commonly and substantially lower.
In selected cases, possibly yes. But not on that basis alone. Diagnosis requires consistent symptoms alongside consistently low levels, and the cause needs establishing. Where a man has persistent symptoms, a low-normal total testosterone and a low calculated free testosterone, and the other causes on this page have been properly excluded, treatment can be a reasonable discussion. That is a considered decision made with a doctor, not a conclusion drawn from a single figure. A borderline result in a man with a large waist and untreated sleep apnoea is usually telling you about the waist and the sleep.
In men with obesity, weight loss raises it meaningfully. Treating sleep apnoea raises it. Adequate sleep, resistance training, reducing alcohol and correcting vitamin D deficiency all contribute. Commercial testosterone-boosting supplements do not have evidence of a clinically meaningful effect in men who are not deficient.
In appropriately selected men with confirmed hypogonadism, with proper monitoring, it has an acceptable risk profile. It requires baseline assessment, haematocrit monitoring, prostate follow-up and a conversation about fertility, and it is not appropriate for men with normal levels seeking optimisation.
In men with genuine deficiency, it improves lean mass. In men with normal levels it is not a legitimate performance intervention, and it carries the risks described above including suppression of fertility.
With sleep, mood, thyroid, iron, glucose and your medication list, and with an honest look at alcohol and training load. In my experience the answer is in that group considerably more often than it is in testosterone.