What Causes Low Testosterone? 10 Common Factors

Understanding Testosterone Production

Testosterone is produced primarily in the testicles, regulated by signals from the pituitary gland and hypothalamus in the brain. This complex hormonal axis can be disrupted at multiple points, leading to low testosterone (hypogonadism).¹

Low testosterone affects an estimated 4-5 million American men, though many cases go undiagnosed. Understanding the causes helps identify the best treatment approach.

1. Age-Related Decline (Andropause)

Testosterone levels naturally decline with age, typically starting around age 30. Men lose approximately 1-2% of their testosterone annually after this point. By age 70, many men have testosterone levels 40-50% lower than in their 20s.²

This gradual decline is sometimes called "andropause" or "male menopause," though it's much more gradual than female menopause. Not all men experience symptoms, but many do.

2. Obesity and Excess Body Fat

Obesity is one of the most significant modifiable risk factors for low testosterone. Fat tissue contains aromatase, an enzyme that converts testosterone to estrogen. The more body fat you carry, the more testosterone gets converted.⁴

Additionally, obesity is associated with insulin resistance, inflammation, and other metabolic changes that further suppress testosterone production. Weight loss can significantly improve levels.

3. Type 2 Diabetes and Insulin Resistance

Men with type 2 diabetes are twice as likely to have low testosterone compared to non-diabetic men. Insulin resistance and chronic high blood sugar damage the cells that produce testosterone and disrupt the hormonal signals from the brain.

4. Sleep Disorders, Especially Sleep Apnea

Most testosterone is produced during deep sleep. Sleep disorders—particularly obstructive sleep apnea—significantly reduce testosterone production. Studies show men with untreated sleep apnea have substantially lower testosterone levels.

Treating sleep apnea with CPAP therapy often improves testosterone levels naturally.

5. Chronic Stress and High Cortisol

Chronic stress elevates cortisol, the body's primary stress hormone. Cortisol and testosterone have an inverse relationship—when cortisol stays elevated, testosterone production decreases.

This is an evolutionary adaptation (stress isn't the time for reproduction), but chronic modern stress keeps testosterone suppressed long-term.

6. Medications That Lower Testosterone

Several common medications can significantly reduce testosterone levels:

• Opioid pain medications: Among the most common causes of medication-induced low T
• Corticosteroids: Long-term use suppresses the hormonal axis
• Certain antidepressants: Some SSRIs affect hormone levels
• Hair loss medications: 5-alpha reductase inhibitors alter hormone metabolism
• Prostate medications: GnRH agonists intentionally lower testosterone

7. Testicular Injury or Conditions

Primary hypogonadism occurs when the testicles themselves are damaged or dysfunctional. Causes include:

• Physical injury to the testicles
• Infections (such as mumps orchitis)
• Cancer treatment (chemotherapy or radiation)
• Genetic conditions (Klinefelter syndrome)
• Undescended testicles

8. Pituitary or Hypothalamic Disorders

Secondary hypogonadism occurs when the brain doesn't properly signal testosterone production. Causes include pituitary tumors, head injuries, certain medications, and inflammatory conditions affecting these brain regions.³

9. Alcohol and Substance Abuse

Chronic heavy alcohol consumption directly damages testosterone-producing cells and disrupts the hormonal axis. Illicit drugs, particularly opioids and anabolic steroids, also significantly impact natural testosterone production.

10. Lifestyle Factors

Several lifestyle factors contribute to testosterone decline:

• Sedentary lifestyle: Lack of exercise, especially resistance training
• Poor diet: Highly processed foods, excessive sugar, nutrient deficiencies
• Chronic inflammation: From diet, obesity, or underlying conditions
• Environmental toxins: Certain chemicals may act as endocrine disruptors