Men Over 40: What Happens to Testosterone?
Men don't experience classic menopause. There's no sudden turning point like there is for women. Even so, hormonal balance does shift. Testosterone declines slowly, over many years, at an average rate of about one to two percent per year starting at age 30. That sounds like little at first, but it adds up over time. After ten or twenty years, this decline can become noticeable, both physically and mentally. Today we understand this process better than before, and we also know which factors influence how pronounced the decline will be.
Testosterone declines slowly, over many years, at an average rate of about one to two percent per year starting at age 30. That sounds like little at first, but it adds up over time. After ten or twenty years, this decline can become noticeable, both physically and mentally. Today we understand this process better than before, and we also know which factors influence how pronounced the decline will be.
What Testosterone Does in the Male Body
Testosterone is more than a hormone for muscles and sexuality. It acts on many areas of the body: bone density, fat distribution, metabolism, mood, drive, mental performance, and the cardiovascular system. A stable testosterone level is often associated with a lower risk of excess weight, type 2 diabetes, and heart disease. Conversely, men with significantly low levels more frequently experience problems in these areas.
The cause isn't always clear-cut. Does low testosterone lead to excess weight, or does excess weight lower testosterone? In practice, both happen. Abdominal fat in particular plays an important role. It can convert testosterone into estrogen and lower levels further, creating a self-reinforcing cycle.
When Is Low Testosterone a Medical Problem?
Not every decline requires treatment. A genuine deficiency is only diagnosed when a persistently low testosterone value is accompanied by typical symptoms. Symptoms alone are not sufficient, and a low lab value without symptoms generally doesn't need to be treated either.
Typical signs can include persistent fatigue and lack of drive, reduced libido or erectile dysfunction, muscle loss alongside increasing abdominal fat, low mood, or the feeling of thinking more slowly. These symptoms, however, overlap significantly with other causes such as stress, sleep deprivation, depression, or excess weight. For this reason, a diagnosis should not be made hastily but always carefully evaluated.
Lab Testing When Testosterone Deficiency Is Suspected
If deficiency is suspected, testosterone is measured in the blood, ideally in the morning when levels are highest, and usually on two separate days. Additional values are also determined. These include SHBG, a protein that binds testosterone and influences how much of it is active in the body. The hormones LH and FSH are also measured to help identify the underlying cause. In addition, thyroid function, prolactin, and a blood count are frequently checked.
Testosterone Replacement Therapy: What the Research Says
Testosterone replacement therapy can be appropriate in cases of a clearly diagnosed deficiency. Studies show that it can have positive effects on body weight, metabolism, bone density, and mood. For a long time there was uncertainty about possible cardiovascular risks. However, more recent studies have not found an increased risk of heart attacks in men with medically confirmed testosterone deficiency. That said, there are indications that caution is warranted in men with pre-existing heart problems. Testosterone is therefore not a general anti-aging measure, but a targeted medical treatment for genuine deficiency.
From Clinical Practice
A man in his mid-forties reports fatigue, declining libido, and the feeling of physically deteriorating. His blood values fall within the lower normal range. After a thorough evaluation, he initially decides against medication and changes his lifestyle instead. More strength training, better sleep, and weight loss lead to measurable improvements in both his values and his sense of wellbeing.
What Naturally Influences Testosterone
Before considering therapy, it's worth looking at lifestyle. Strength training can measurably increase testosterone levels, especially with intense work involving large muscle groups. Adequate sleep is crucial, as testosterone is produced primarily during sleep. Sleep deprivation can lower levels significantly within just a few days. Body weight also plays a role, particularly abdominal fat. When reduced, hormonal balance improves. Larger quantities of alcohol lower testosterone, and chronic stress also has a negative effect by inhibiting production.
When to See a Doctor
If symptoms such as fatigue, loss of libido, muscle loss, or erectile dysfunction persist over a longer period, a medical evaluation is warranted. A blood test is a simple first step, but interpreting the results requires experience and should not be done on one's own.
What You Can Do Now
Regular strength training, adequate sleep, reducing abdominal fat, and a conscious approach to alcohol are the most important levers for positively influencing testosterone levels. At the same time: self-diagnosis or self-treatment is not a good solution. If deficiency is suspected, evaluation should always be carried out by a physician.
Sources
Hudson, J. et al. (2022). Adverse cardiovascular events and mortality in men during testosterone treatment: a meta-analysis. Lancet Healthy Longevity, 3:e381-393.
Lincoff, A.M. et al. (2023). Cardiovascular safety of testosterone-replacement therapy. N Engl J Med, 389:107-117.
Stallone, J.N. et al. (2023). Cardiovascular and metabolic actions of androgens. Biochem Pharmacol, 208:115347.
Feldman, H.A. et al. (2002). Age trends in testosterone levels: longitudinal results from the Massachusetts Male Aging Study. J Clin Endocrinol Metab, 87(2):589-598.
Borges, J.Y.V. (2024). The inverse association between testosterone replacement therapy and cardiovascular disease risk: a 25-year review. medRxiv preprint.
