Knowing what causes low testosterone is important for prevention and treatment. Many people first think of "aging," but the real picture is more complicated. While age-related decline is common, it is usually not the only cause. This article looks at all the possible reasons for low testosterone, from biology to lifestyle, so you can talk more confidently with your healthcare provider.
Age-Related Decline: The Most Common Factor
Around age 30, most men start to see a slow drop in testosterone production, usually about one to two percent each year. This happens because of changes in the hypothalamic-pituitary-gonadal (HPG) axis, which is the hormone system that controls testosterone. As time goes on, the signals from the brain to the testes get weaker, and the testes do not respond as well.
By the time a man is in his fifties or sixties, this steady drop can lead to much lower testosterone levels than he had in his twenties and thirties. However, the rate of decline is different for everyone. Some men keep healthy levels into old age, while others have low levels much sooner.
Obesity and Metabolic Health
Having too much body fat, especially around the belly, is one of the main changeable reasons for lower testosterone. Fat tissue has an enzyme called aromatase that turns testosterone into estrogen. The more fat you have, the more this happens, and your testosterone levels drop. This can become a cycle: low testosterone leads to more fat, and more fat lowers testosterone even further.
Metabolic conditions, including type 2 diabetes, insulin resistance, and metabolic syndrome, are also strongly associated with low testosterone. Research suggests these conditions may affect both testicular function and the HPG axis.
Sleep and Stress
Testosterone production is closely tied to sleep quality. The majority of daily testosterone release occurs during sleep, particularly during REM stages. Men who consistently get fewer than five to six hours of quality sleep per night have been shown to have significantly lower testosterone levels than those who sleep seven to nine hours.
Chronic stress is another contributor. Prolonged stress elevates cortisol, and elevated cortisol has an inverse relationship with testosterone—when one goes up, the other tends to go down. Chronic high cortisol can suppress the HPG axis and directly impair testosterone production.
Medical Conditions and Medications
Several medical conditions can cause or contribute to low testosterone. These include pituitary disorders that reduce LH and FSH production, testicular injury or conditions affecting the testes, chronic kidney or liver disease, HIV/AIDS, hemochromatosis (iron overload), and autoimmune conditions. Certain medications can also suppress testosterone, including opioid pain medications, corticosteroids, some antidepressants, and certain chemotherapy drugs.
Lifestyle Factors You Can Control
Beyond the medical causes, several lifestyle factors contribute to testosterone decline and are within your control. Excessive alcohol consumption suppresses the HPG axis and can damage testicular tissue over time. Sedentary behavior is associated with lower testosterone levels, while regular resistance training has been shown to support healthy testosterone levels. Poor nutrition—particularly diets very low in fat or deficient in zinc, vitamin D, and magnesium—can impair testosterone production. And environmental exposures to certain endocrine-disrupting chemicals may also play a role.
Getting to the Root Cause
Effective treatment starts with understanding what's driving your low testosterone. A thorough evaluation should look beyond the testosterone number itself and assess contributing factors, including metabolic health, sleep quality, stress levels, medication history, and overall lifestyle. At HRT Wellness, our evaluations are designed to identify not just low testosterone but the factors behind it, so your treatment plan addresses root causes alongside symptom management. Schedule a consultation to start the process.
References
- Bhasin S, et al. Testosterone therapy in men with hypogonadism. Journal of Clinical Endocrinology & Metabolism. 2018;103(5):1715–1744.
- Leproult R, Van Cauter E. Effect of 1 week of sleep restriction on testosterone levels in young healthy men. JAMA. 2011;305(21):2173–2174.
- Grossmann M. Low testosterone in men with type 2 diabetes. Journal of Clinical Endocrinology & Metabolism. 2011;96(8):2341–2353.