How Aging Affects Testosterone

When people think of testosterone, they often associate it with male sexual health. However, this hormone affects much more than that—it influences energy, muscle strength, bone health, and even mood. As men enter middle age, hormone changes happen quietly but can have noticeable effects.

This article explains what testosterone is, how it changes with age, and ways to stay healthy and energetic by managing these changes.

About Testosterone

Testosterone is a steroid hormone and the primary androgen in men [8]. It plays a key role in many functions, including sexual desire, aggression, emotions, cognition, energy, and mood [8]. It also supports muscle growth, bone strength, fat distribution, and red blood cell production [7, 8].

How Aging Affects Testosterone

Natural Decline With Age

Testosterone levels in men naturally decrease with age, starting around 30–35 years old [8]. Free testosterone (the unbound, active form) and bioavailable testosterone (the portion available for use) decline faster than total testosterone [2].

A study in China found that free testosterone drops about 1.3% per year, while total testosterone decreases by about 0.4% annually in men aged 40 to 70 [2].

When testosterone falls below normal levels, a condition called hypogonadism can occur, which becomes more common as men age. About 20% of men over 60 and 35% of men over 80 have lower total testosterone than younger men [1, 7].

However, not everyone experiences this decline to the same degree, as it depends on various factors [5].

One key factor is Sex-Hormone Binding Globulin (SHBG), a protein in the blood that binds to testosterone. As men age, SHBG levels rise, reducing the amount of free and bioavailable testosterone [7].

Chronic illnesses and unhealthy lifestyles also speed up testosterone decline [1]. Obesity, diabetes, heart disease, stress, smoking, or excessive alcohol can worsen the drop.

For example, obesity increases the activity of an enzyme called aromatase in fat tissue, which converts testosterone into estrogen, further lowering testosterone levels [1].

Genetics also play a role. The length of CAG repeats in the androgen receptor gene can affect how quickly testosterone declines. Men with shorter CAG repeats tend to experience a faster drop [1, 7].

The Massachusetts Male Aging Study (MMAS), which followed 1,709 men aged 39–70, showed that men with poor health (such as obesity, alcoholism, or chronic diseases) had testosterone levels about 10% lower than healthier men of the same age.

This suggests that while testosterone decline is a normal part of aging, health and lifestyle factors can make it more significant [5].

Physical Health Effects

Testosterone decline affects muscles noticeably. As levels drop, men often lose muscle mass and strength [8]. Testosterone helps build and maintain muscles, so a deficiency leads to reduced physical strength.

In younger men with hypogonadism, testosterone replacement therapy (TRT) can improve lean muscle mass, muscle size, and strength. However, in older men, the effect is less pronounced [10].

A classic study by Urban and colleagues (1995) found that testosterone supplementation in healthy older men with levels below 480 ng/dl increased leg strength and muscle protein synthesis [7]. This is partly because testosterone boosts IGF-1 expression, which supports muscle protein production [7].

Testosterone is also critical for bone health. Low levels increase the risk of osteoporosis and fractures [1]. In younger men with hypogonadism, TRT can help reduce bone loss and improve bone density [8].

Some studies show testosterone’s positive effect on bones, but this depends on its conversion to estradiol. More large-scale studies are needed to fully understand its impact on bone health [10].

Testosterone also affects metabolism and fat distribution. As levels decline with age, men tend to gain fat, especially around the abdomen, and their metabolism slows [8].

Obesity can further lower testosterone, as fat tissue converts testosterone into estrogen via aromatase [1].

Testosterone helps reduce fat absorption and the activity of lipoprotein-lipase in fat cells [7]. It also increases fat breakdown through catecholamines by boosting beta-adrenergic receptor numbers and limits the formation of new fat cells [7].

Cognitive and Emotional Effects

Testosterone doesn’t just affect the body—it also impacts the brain. It influences areas involved in learning and memory, particularly the hippocampus, which has many androgen receptors.

As testosterone declines with age, memory and cognitive functions may weaken, potentially increasing the risk of cognitive decline or dementia.

Some studies suggest that maintaining stable testosterone levels, naturally or through supplementation, may benefit brain health and protect neurons from damage [6].

Testosterone is also linked to energy and mood. Low levels can lead to fatigue, sadness, irritability, or loss of interest in daily activities [8].

Reports and real-world experiences show that TRT can improve well-being, sleep, sexual desire, and optimism. However, research on its effects on depression and quality of life in older men is mixed [10].

Still, evidence suggests that androgen supplementation may help reduce depression symptoms in some men with hypogonadism (Seidman & Walsh, 1999).

A notable study by Wang and colleagues (1996) followed 51 men with hypogonadism for 2–6 months of treatment and found significant improvements: higher energy, friendliness, and well-being, with reduced stress, irritability, and sadness [9]. This supports the idea that testosterone directly affects emotions and mental state.

Testosterone also regulates behaviors like sexual arousal, aggression, and social motivation. In humans, it’s tied to sexual desire, thrill-seeking, dominance, and responses to success or failure. Testosterone levels may drop during stress or failure but rise with victories or social achievements [8].

How to Maintain Testosterone as You Age? 

Maintaining testosterone levels as you age depends not only on natural biology but also on managing health conditions, lifestyle, and daily habits. Here are key factors that can help protect your testosterone and overall health.

First, address underlying health conditions. Studies show that men with chronic illnesses like obesity, diabetes, heart disease, high blood pressure, or chronic kidney disease often have lower testosterone.

Managing these conditions improves overall health and helps stabilize hormone levels. For example, testosterone is often lower in men who’ve had a heart attack [7].

Stress is another major factor. Both physical and mental stress can lower testosterone while raising cortisol, a hormone that causes fatigue. Reducing stress can help testosterone return to normal levels (Mudali, 2004).

Alcohol and smoking also impact testosterone. Heavy or prolonged drinking significantly lowers testosterone, but quitting can help levels recover [7]. The link between smoking and testosterone is complex—some studies suggest smokers have higher total testosterone, while others show heavy smoking reduces it [3, 8].

Lifestyle changes are crucial for maintaining testosterone. Regular exercise, especially moderate aerobic activity for about 150 minutes per week, can make a big difference. One study found that short-term moderate exercise increased serum testosterone by 39% and free testosterone by 23% in older men [2].

Maintaining a healthy weight is also essential. In obese men, fat tissue converts testosterone into estrogen via aromatase, reducing available testosterone. Weight loss has been shown to improve testosterone levels in many men [3, 4, 7].

Relaxation techniques like meditation, deep breathing, or proper rest can reduce stress and help manage testosterone decline [7].

Diet-wise, some studies suggest vegetarian diets may lead to higher total testosterone, but free testosterone levels are similar to those of meat-eaters [7]. The key is a balanced, healthy diet to support overall health.

When to See A Doctor for Low Testosterone?

While testosterone decline is a natural part of aging, abnormally low levels can cause significant health issues, affecting physical, mental, and quality-of-life aspects. Seeing a doctor is crucial in these cases.

Common signs of low testosterone include changes in sexual function, such as reduced desire, difficulty maintaining erections (especially morning erections), or less interest in sexual activities. In some cases, it may affect ejaculation or fertility [7, 8].

Low testosterone can also impact mood and emotions. Men may feel persistently sad, depressed, irritable, anxious, or fatigued, with a lack of enthusiasm for daily life (Seidman & Walsh, 1999).

Cognitively, some notice reduced focus, forgetfulness, or lower productivity in daily tasks (Seidman & Walsh, 1999). These subtle changes can affect confidence and adaptability.

Physically, low testosterone is linked to muscle loss, reduced strength, and increased body fat, especially around the abdomen. Over time, it can also reduce bone density, raising the risk of osteoporosis and fractures [8].

If you experience these symptoms for an extended period—especially a combination of low sexual desire, lack of morning erections, mood changes, and low energy—it’s time to talk to a doctor. A blood test can measure testosterone levels accurately (Seidman & Walsh, 1999).

If hypogonadism is suspected, an endocrinologist or urologist can provide a thorough evaluation and discuss treatment options, including the benefits and risks of TRT [8].

Listening to your body and noticing unusual changes is key to long-term health. If caught early, low testosterone can be managed to improve quality of life in middle and older age.

Conclusion

Testosterone is vital for men’s health, and its natural decline with age is normal. However, its impact varies from person to person, and proactive health management can help you adapt to these changes.

To maintain quality of life, combine healthy habits with professional guidance when needed. More than just focusing on testosterone levels, pay attention to how your body and mind are functioning.