Testosterone in Decline: Why Men Have Lower Levels Today — and How Naturopathy Can Help
Laura Chrobok 07.09.2026
Less interest in sex, declining muscle strength, increasing abdominal fat, fatigue and a general drop in performance: such symptoms are often associated with low testosterone levels. But there may be more to this than individual hormone levels. Studies from the USA suggest that men’s average testosterone levels have indeed fallen over recent decades — and apparently not simply because the population has grown older.
In today’s article, we explain what lies behind the observed decline in testosterone, which factors have a particularly strong influence on male hormone balance — and what men themselves can do to create favourable conditions for normal testosterone production.
Testosterone Is Far More Than a Sex Hormone
Testosterone belongs to the group of androgens, the male sex hormones. In men, it is produced primarily in the testes. Its production is regulated by a finely tuned interplay between the hypothalamus, pituitary gland and testes.
Its importance extends far beyond libido and sexual function. Testosterone influences muscle mass and strength, bone metabolism, fat distribution, blood formation and sperm production (European Association of Urology, 2026).
Accordingly, the consequences of a pronounced deficiency can be wide-ranging.
Declining Testosterone Levels Are Not New Observations
The Massachusetts Male Aging Study provided a particularly interesting indication. Testosterone measurements from American men taken between the late 1980s and the early 2000s were analysed.
The researchers found a marked decline in testosterone. And the effect could not simply be explained by the men getting older. Smoking, changes in weight and other health and lifestyle factors did not fully explain the decline either (Travison et al., 2007).
The picture becomes even more interesting when looking at younger men. An analysis of data from 4,045 adolescents and men aged 15 to 39 from the US NHANES health surveys conducted between 1999 and 2016 found that average total testosterone levels were lower in later survey periods than at the beginning of the study period. A higher BMI was associated with lower testosterone — but the downward trend over time persisted even among men of normal weight (Lokeshwar et al., 2021).
This is noteworthy, but it is not proof of a worldwide “testosterone crash”. Both studies come from the USA, and when comparing values over long periods, differences in populations, laboratory methods and other influencing factors have to be taken into account.
Why testosterone levels are declining at all has not yet been conclusively established.
Age Alone Is No Explanation
It is well known that testosterone tends to decline over the course of a lifetime. However, the relationship between age and testosterone is strongly influenced by other health factors. European clinical guidelines point out that obesity and the conditions often associated with it may account for a considerable proportion of low testosterone levels in older age, while the effect of ageing alone may be comparatively limited (European Association of Urology, 2026).
A low testosterone level is therefore not automatically an inevitable consequence of ageing.
The Various Factors That Can Disrupt Testosterone Levels
Several modifiable factors play a role:
· Obesity
One of the most important modifiable factors is excess weight — particularly pronounced obesity.
Adipose tissue is not a passive energy store but is hormonally and metabolically active. In obesity, insulin, leptin, inflammatory and oestrogen signalling, among other processes, are altered. These changes can interfere with hormonal regulation between the brain and testes and contribute to functional secondary hypogonadism (Fernandez et al., 2019).
At the same time, testosterone deficiency is often associated with less lean body mass and a less favourable distribution of body fat. The crucial point, however, is that this condition may be at least partially reversible.
A meta-analysis of 24 studies showed that weight loss in overweight or obese men was associated with an increase in testosterone. There was also an association between the amount of weight lost and the increase in testosterone (Corona et al., 2013).
Men who lose a substantial amount of excess weight therefore improve not only conventional metabolic parameters. Male hormone balance impaired by obesity can also recover.
· Other Illnesses and Medicines
In addition to obesity, type 2 diabetes and other metabolic disorders, as well as diseases of the testes, pituitary gland or hypothalamus, can be associated with testosterone deficiency.
Adding more testosterone from an external source therefore by no means automatically results in better long-term function of the body’s own hormonal system.
Medicines can also play a role. These include, for example, opioids and glucocorticoids used over longer periods (European Association of Urology, 2026).
The unsupervised use of testosterone or anabolic steroids is particularly problematic. Supplying the body with androgens from an external source can suppress its own hormonal regulation. The testes receive fewer stimulating signals, which can considerably reduce the body’s own production of testosterone and sperm.
· Lack of Sleep
A substantial proportion of daily testosterone secretion is linked to sleep. A small controlled study from the University of Chicago attracted considerable attention: 10 healthy young men were initially allowed to get sufficient sleep and then restricted to only five hours of sleep per night for one week. Following the period of sleep restriction, their testosterone levels were lower at certain times of day than when they were well rested (Leproult & Van Cauter, 2011).
The study was small and does not allow a general statement about the percentage by which sleep deprivation reduces testosterone in every man. But it highlights an important point: sleep is not merely a period of recovery; it is part of hormonal regulation. Persistently getting too little sleep does not provide good conditions for stable hormone balance.
· Environmental Chemicals
The role of endocrine disruptors is intriguing — and still far from being fully understood. These are substances foreign to the body that can interfere with hormonal systems.
Among the groups of substances studied particularly intensively are phthalates, which have been or continue to be used in various plastics and other everyday products.
A systematic review with meta-analysis published in 2024 examined the association between exposure to di(2-ethylhexyl) phthalate (DEHP) and reproductive hormones. The analysis included 37 studies with a total of 28,911 participants. In men, higher DEHP exposure or certain metabolites were associated with changes in various reproductive hormones; some analyses also found an inverse relationship with total testosterone (Li et al., 2024).
Such observations do not prove that phthalates cause testosterone deficiency in an individual man. Nor do they prove that environmental chemicals explain the long-term decline.
Nevertheless, investigating hormonally active environmental substances as a possible contributing factor is by no means mere speculation. The question is scientifically relevant — but the answer is more complicated than claiming that a single substance is responsible for the entire trend.
Recognising Testosterone Deficiency
Testosterone deficiency can never be diagnosed from a list of symptoms alone. Nevertheless, a pronounced deficiency can be associated with symptoms including:
· reduced sexual desire
· fewer spontaneous or morning erections
· erectile dysfunction
· loss of muscle mass and physical performance
· increased fat mass
· fatigue and lack of drive
· mood changes
· reduced bone density
· impaired fertility.
Symptoms relating to sexual function are particularly informative. Other symptoms, such as fatigue or difficulty concentrating, are considerably less specific (European Association of Urology, 2026).
A Single Testosterone Measurement Is Not Conclusive
A single low measurement does not in itself prove hypogonadism, i.e. pathological underactivity of the gonads resulting in insufficient testosterone production.
Testosterone levels fluctuate naturally. For a diagnosis, appropriate clinical symptoms must be present alongside consistently low testosterone levels. A morning measurement under standardised conditions is therefore recommended. If the level is low, it should be confirmed with a further morning measurement (Bhasin et al., 2018; European Association of Urology, 2026).
Depending on the findings, it may be useful to check additional values. These include SHBG and free testosterone, as well as the regulatory hormones LH and FSH. The latter help to determine whether the problem is more likely to be related to the testes or to the higher-level hormonal control system.
For this reason, attempting to treat a presumed deficiency on your own is not a good idea: the first step is to establish whether a deficiency actually exists — and why.
Increasing Testosterone — What Really Works
In the case of an organic disorder of the testes or the hormonal control centres, genuine hypogonadism cannot be eliminated by a particular food, strength training or a dietary supplement. The situation is different with functionally low levels associated, for example, with obesity and metabolic problems.
There is particularly concrete evidence that weight loss in overweight men is associated with an increase in testosterone (Corona et al., 2013).
That may sound less spectacular than “testosterone boosters”, but it makes sense: instead of trying to artificially optimise a single laboratory value, the aim is to change factors that affect the entire metabolism and therefore hormonal regulation as well.
· Testosterone Replacement Therapy (TRT)
In cases of medically confirmed hypogonadism, testosterone replacement therapy can improve symptoms and may be medically appropriate. Before treatment begins, the cause, possible contraindications and individual risks must be considered. Testosterone and haematocrit, among other parameters, are monitored during treatment (Bhasin et al., 2018; European Association of Urology, 2026).
Particular caution is required, however, if a man wishes to have children. Testosterone supplied from an external source suppresses hormonal stimulation of the testes and can therefore considerably reduce sperm production. Men who wish to preserve their fertility or father children in the foreseeable future should therefore not hastily begin conventional testosterone replacement therapy (Bhasin et al., 2018).
· Zinc
The trace element zinc is involved in numerous biological processes that are also relevant to male reproductive function and hormone metabolism. A systematic review concludes that deficiency may be associated with lower testosterone levels and that zinc supplementation may improve levels, particularly when zinc intake is inadequate (Te et al., 2023). However, this likewise does not mean that taking additional high doses of zinc automatically results in more testosterone in men who already have an adequate zinc status.
· Magnesium
Magnesium is also frequently included in so-called “testosterone boosters”, sometimes together with zinc. However, the evidence for specifically increasing testosterone through magnesium in men without a corresponding deficiency is not convincing (Morgado, A. et al., 2024).
Testosterone Conclusion: What’s a Man Gotta Do?
Simple explanations do not do justice to the issue.
It is too simplistic to dismiss low testosterone levels across the board as a normal consequence of ageing. The association with obesity and metabolic health is particularly well established. Sleep, illnesses and certain medicines can also influence hormone balance. Environmental chemicals remain an important area of research in which many questions are still unanswered.
For men experiencing symptoms, this means: do not blindly try to “boost” testosterone — look for the cause.
And for men with functionally low levels, some of the most effective measures are not found on the supplement shelf but in everyday life: maintaining a healthy body weight or losing weight if overweight, exercising regularly, getting enough sleep and treating existing metabolic or underlying conditions.
FAQ — Frequently Asked Questions About Testosterone Deficiency
1. Who should I consult if I suspect that my testosterone level is too low?
An initial assessment can be carried out by a GP. Depending on the findings, urologists, andrologists or endocrinologists may be appropriate for further diagnostic investigations.
2. Should every man have his testosterone level checked regularly?
No, testing is particularly appropriate if typical symptoms or certain illnesses or risk factors are present. A single low measurement is also insufficient as the basis for either a diagnosis or treatment. What matters are repeatedly low levels, corresponding symptoms and the underlying cause.
3. Does low testosterone always cause erectile problems?
No, erectile dysfunction can, for example, be caused by vascular disease, diabetes, neurological disorders, medicines or psychological factors. Testosterone deficiency is only one possible cause.
Further information — also on many other topics — can be found on our blog. You can also find our “Medizinskandale” book series and the “Codex Humanus”, the fifth volume of which was recently published, in our online shop. We look forward to your visit.
Sources:
· European Association of Urology (2026): “Male Hypogonadism,” EAU Guidelines on Sexual and Reproductive Health.
· Travison, T. G. et al. (2007): “A Population-Level Decline in Serum Testosterone Levels in American Men,” The Journal of Clinical Endocrinology & Metabolism.
· Lokeshwar, S. D. et al. (2021): “Decline in Serum Testosterone Levels Among Adolescent and Young Adult Men in the USA,” European Urology Focus.
· Fernandez, C. J. et al. (2019): “Male Obesity-related Secondary Hypogonadism – Pathophysiology, Clinical Implications and Management,” European Endocrinology.
· Corona, G. et al. (2013): “Body Weight Loss Reverts Obesity-associated Hypogonadotropic Hypogonadism: A Systematic Review and Meta-analysis,” European Journal of Endocrinology.
· Leproult, R.; Van Cauter, E. (2011): “Effect of 1 Week of Sleep Restriction on Testosterone Levels in Young Healthy Men,” JAMA.
· Li, X. et al. (2024): “Association of Di(2-ethylhexyl) Phthalate Exposure with Reproductive Hormones in the General Population and the Susceptible Population: A Systematic Review and Meta-Analysis,” Environment & Health.
· Bhasin, S. et al. (2018): “Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline,” The Journal of Clinical Endocrinology & Metabolism.
· Te, L. et al. (2023): “Correlation between Serum Zinc and Testosterone: A Systematic Review,” Journal of Trace Elements in Medicine and Biology.
· Morgado, A. et al. (2024): “Do ‘Testosterone Boosters’ Really Increase Serum Total Testosterone? A Systematic Review,” International Journal of Impotence Research.
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