You have seen the advertising. A tired man in his forties, a chart falling from left to right, and a promise that the testosterone decline is stealing your energy, your muscle, your drive and your marriage. Then a supplement, a clinic subscription, or a telehealth consultation that ends in a prescription with striking reliability.

Here is the uncomfortable part for anyone hoping this is simply a scam: the underlying claim is true. Average testosterone in men really has fallen over the past forty years, it has fallen independently of age, and it has been documented in multiple countries by researchers with no product to sell.

The problem is everything that gets bolted onto that fact afterwards.

The short version

• The population-level testosterone decline is real. A 60-year-old man in the early 2000s had roughly 17% less testosterone than a 60-year-old in the late 1980s.
• It persisted after adjusting for age, weight, smoking and illness, which means it is not simply an obesity story.
• It has since been found in men aged 15 to 39, and in several other countries.
• What does not follow is that you personally have low testosterone, or that treating it is the answer.
• The largest trial ever run found no increase in major cardiac events, but did find more atrial fibrillation, pulmonary embolism and acute kidney injury.
• That trial’s own chair said explicitly it should not be used to justify widespread prescribing to ageing men. It is used that way constantly.
• The regulatory position on treating testosterone decline changed significantly in 2025 and again in 2026

This article is about evidence, not advice. Nothing here is a substitute for testing and a conversation with your own doctor.

What is genuinely true about the testosterone decline

The foundational study is Travison and colleagues, published in the Journal of Clinical Endocrinology and Metabolism in 2007. It drew on the Massachusetts Male Aging Study, which measured testosterone in three separate cohorts of men between 1987 and 2004.

The design is what makes it convincing. Because the study sampled different men at different times, it could compare like with like across the calendar. Not the same man ageing, but a 60-year-old in 1988 against a 60-year-old in 2003.

The 60-year-old in the early 2000s had average total testosterone roughly 17 percent lower.

Why it is not just an obesity story

The obvious explanation is that men got heavier, and body fat lowers testosterone. The researchers tested that directly.

The gap persisted after adjusting for age, body mass index, smoking status and health conditions. Travison’s own summary was that the decline does not appear attributable to observed changes in explanatory factors including health and lifestyle. Shalender Bhasin, reviewing it, made the same point: the usual suspects did not account for it.

Worth noting one counterintuitive wrinkle. Smoking is associated with higher testosterone, so the welcome collapse in smoking rates over this period should have pushed averages down for entirely benign reasons. Even allowing for that, the decline remained.

It is now visible in young men

A 2021 analysis in European Urology Focus examined American men aged 15 to 39 between 1999 and 2016 and found average testosterone falling in that group too.

This matters because it removes the last comfortable interpretation. This is not older men declining slightly faster than they used to. A 22-year-old today has, on average, less testosterone than a 22-year-old thirty years ago.

It is not only American

Comparable secular declines have been reported in Denmark, Finland and Norway over a similar window. A Danish analysis found double-digit declines among men born in the 1960s compared with earlier birth cohorts.

Taken together, the literature points to something on the order of one percent per year since the late 1980s, largely independent of age. In any single year that is nothing. Compounded over four decades it is substantial.

A 22-year-old today has, on average, less testosterone than a 22-year-old thirty years ago. Age is not the variable that changed.

The testosterone decline caveat the industry never mentions

Before going further, the honest limitation.

Measuring testosterone is harder than it sounds, and the laboratory methods used to do it have changed considerably since the 1980s. Some researchers have cautioned that shifts in assay methodology and in population characteristics over time may partly influence the observed trends.

This does not dissolve the finding. Multiple studies adjusting for such factors have found the decline persists, and the consistency across different countries using different laboratories argues against it being a measurement artefact. But anyone presenting the testosterone decline as a settled number with no methodological questions attached is overselling.

There is a second, larger gap. Nobody has established the cause. Endocrine-disrupting chemicals, obesity, sedentary behaviour, sleep loss, chronic stress and medication use are all plausible contributors and all appear in the literature. None has been isolated. A narrative review in 2025 lists them collectively as likely contributors, which is the honest position and a considerably less satisfying one than any advertisement will offer you.

Where testosterone decline marketing departs from the evidence

Everything above is defensible. Here is where the sales pitch stops tracking the science.

A population average is not your blood test

This is the central sleight of hand in almost all testosterone decline marketing.

The testosterone decline is a statement about the mean of a population across decades. It says nothing whatever about any individual man. The distribution is wide. Plenty of men today sit at levels that would have been unremarkable in 1985, and plenty of men in 1985 had levels that would concern a doctor now.

You cannot infer your own status from a trend line. You can only find it out by being tested, ideally more than once, in the morning, because levels fluctuate substantially through the day.

The symptom list is deliberately universal

Low energy. Poor concentration. Reduced libido. Irritability. Difficulty building muscle. Low mood. Poor sleep.

Every one of these is a genuine symptom of clinically low testosterone. Every one is also a symptom of ordinary sleep deprivation, depression, thyroid dysfunction, anaemia, sleep apnoea, chronic stress, or being forty-three with two children and a demanding job.

A checklist that returns a positive result for most of the adult male population is not a diagnostic instrument. It is a lead generator. This is why the sequence matters: test first, then interpret symptoms in light of the result, rather than using symptoms to decide you already know the answer.

Supplements are a separate category entirely

Worth being blunt about the distinction. Prescription testosterone is a regulated drug with trial data behind it. Over-the-counter testosterone boosters are supplements, which in most markets means they are not assessed for efficacy before sale.

Where a genuine deficiency exists, such as vitamin D or zinc, correcting it can help. That is treating a deficiency, not boosting a hormone. For men who are not deficient, the evidence that these products meaningfully raise testosterone is thin.

What the biggest testosterone decline trial actually found

Now the study that gets cited more than any other in this space, usually by people who have read the headline rather than the paper.

TRAVERSE was mandated by the FDA in 2015 after reports of strokes, heart attacks and deaths in men using testosterone products. A consortium of manufacturers funded it, and the Cleveland Clinic ran it.

It enrolled 5,246 men aged 45 to 80 who had existing cardiovascular disease or were at high risk of it, randomised them to daily testosterone gel or placebo gel, and followed them for an average of 22 months. Results appeared in the New England Journal of Medicine in 2023.

Major adverse cardiac events occurred in 7.0 percent of men on testosterone and 7.3 percent on placebo. A hazard ratio of 0.96. Noninferior.

The findings that get left out

The trial also found more atrial fibrillation, more pulmonary embolism, and more acute kidney injury among men taking testosterone.

Separately, FDA-required blood pressure monitoring studies found that testosterone products raise blood pressure across the whole class, regardless of how they are administered. That warning was added to the labelling.

So the accurate summary is not “proven safe.” It is: no signal for heart attacks and strokes in this population, alongside other risks that are real and modest.

What the study chair said

Steven Nissen, who chaired the trial, was unusually direct about how it should be read. He noted that the cardiovascular safety findings apply to the population studied, not to men who lack any indication for testosterone therapy but receive it anyway through low-T centres or unscrupulous prescribers, and said plainly that the study should not be used as justification for widespread prescription of testosterone to ageing men.

That sentence is worth holding onto, because TRAVERSE is now routinely cited by exactly the businesses it was warning about.

The trial’s own chair said it should not justify widespread prescribing to ageing men. It is now cited to do precisely that.

The regulatory ground just moved

This part is recent enough that most articles on the subject are out of date, and it matters commercially.

For years, US testosterone products carried two constraints. A boxed warning about cardiovascular risk, added after the 2014 safety review. And a limitation of use stating that safety and efficacy had not been established for age-related hypogonadism, meaning low testosterone attributable to ageing alone rather than to an identifiable disease of the testes or pituitary.

In February 2025, following TRAVERSE, the FDA recommended removing the cardiovascular boxed warning while adding a new warning about increased blood pressure. The limitation of use for age-related hypogonadism was retained at that point.

In June 2026, the FDA requested further changes, including removal of that limitation of use, along with revisions to the prostate cancer and benign prostatic hyperplasia language. The announcement came from the Department of Health and Human Services.

Read the sequence plainly. The label has moved, in roughly eighteen months, from one that explicitly said this was not established for age-related low testosterone to one that no longer says so. Whatever the scientific merits, the commercial consequence is straightforward: the single largest regulatory obstacle to marketing testosterone to ageing men has been removed.

Expect advertising volume to rise accordingly. A label change is not the same as evidence of benefit, and the two will be presented as if they were.

What the testosterone decline means practically

Five things, and none of them involve buying anything.

Get tested before concluding anything. Morning sample, and repeat it, because a single reading is not a diagnosis. If the number is low, the next question is why, and that means looking for an actual cause rather than reaching immediately for replacement.

Rule out the common alternatives first. Sleep apnoea, depression, thyroid problems and anaemia produce the same symptom list and are all more common than clinically low testosterone. A doctor investigating fatigue properly will check these. A clinic selling testosterone often will not.

Treat the modifiable inputs seriously. Sleep, body composition, alcohol and physical activity all influence testosterone decline at the individual level and all sit within your control. This is unglamorous and it is where the actual evidence for improvement in men without a diagnosed deficiency lies.

Understand what starting replacement means. Exogenous testosterone suppresses the body’s own production, and it commonly reduces fertility. For most men it is not a trial you can casually run for six months. This is a conversation to have properly with a doctor before beginning, not after.

Be suspicious of any provider whose diagnostic process ends in a sale. The structural problem with the low-T clinic model is not that testosterone never helps. It is that the same organisation diagnoses the condition and sells the treatment.

Common questions

Is the testosterone decline caused by microplastics?

Endocrine-disrupting chemicals are among the plausible contributors and appear throughout the literature. None has been established as the cause. Anyone telling you it is definitely one specific thing, particularly if they are selling the remedy, is ahead of the evidence.

What counts as low?

Reference ranges vary between laboratories and no single threshold is universal. This is exactly why interpretation belongs with a doctor who can read your result against your symptoms, your age and the lab’s own range, rather than against a number you found online.

Does lifting weights raise testosterone?

Resistance training produces acute post-exercise rises, and those short-term spikes appear to have little to do with long-term muscle gain. The more useful effects come indirectly, through improved body composition and sleep.

Is TRT safe now that the boxed warning is gone?

The warning was removed because the large trial found no increase in major cardiac events in the population studied. Blood pressure effects were added to the label at the same time, and atrial fibrillation, pulmonary embolism and kidney injury were more frequent in the treatment group. Safe is not the word. Better characterised is.

Do testosterone boosters work?

If you are deficient in something specific, correcting that deficiency may help. Beyond that, the evidence is weak and the category is largely unregulated for efficacy.

Does the testosterone decline mean my levels are low?

No. The testosterone decline describes a population average shifting over decades. Your own level can only be established by testing, and many men today sit comfortably within historically normal ranges.

What to take from this

The testosterone decline is one of the rare cases where the alarming claim in the advertisement is actually supported. Levels have fallen, across generations, in multiple countries, independently of age, for reasons nobody has pinned down.

What does not follow is any of the rest of it. Not that you personally are affected. Not that your tiredness is hormonal. Not that a subscription fixes it. The gap between a true population-level trend and a personal diagnosis is where an entire industry has set up shop.

The useful response is boring and cheap. Get tested properly. Rule out the more common explanations. Fix sleep and body composition, which are the levers with real evidence behind them for men without a diagnosis.

And treat any company that both identifies your problem and sells its solution with the scepticism that arrangement deserves.

More in our Health section.

References

1. Travison, T. G., Araujo, A. B., O’Donnell, A. B., Kupelian, V., & McKinlay, J. B. (2007). A population-level decline in serum testosterone levels in American men. Journal of Clinical Endocrinology & Metabolism, 92(1), 196-202. DOI: 10.1210/jc.2006-1375
2. Lokeshwar, S. D., Patel, P., Fantus, R. J., et al. (2021). Decline in serum testosterone levels among adolescent and young adult men in the USA. European Urology Focus, 7(4), 886-889.
3. Andersson, A. M., Jensen, T. K., Juul, A., et al. (2007). Secular decline in male testosterone and sex hormone binding globulin serum levels in Danish population surveys. Journal of Clinical Endocrinology & Metabolism, 92(12), 4696-4705.
4. TRAVERSE trial results (2023). New England Journal of Medicine. Summarised in FDA Testosterone Information.
5. FDA, class-wide labeling changes for testosterone products (February 2025 and June 2026 updates).
6. Nissen, S. Commentary on TRAVERSE findings, Cleveland Clinic Consult QD.
7. Understanding the secular decline in testosterone: mechanisms, consequences, and clinical perspectives. Narrative review, PMC12841019.

This article summarises published research. It is not medical advice and should not be used to diagnose or treat any condition. Testosterone is a prescription medicine with real risks. Speak to a qualified doctor about testing and treatment.