Testosterone is one of the most important male hormones that is key to our well-being.
Here are 23 statistics about testosterone you might not even have known.
#1 How many men have low testosterone
According to some studies, approximately 40% of men over the age of 45 and 50% of men in their 80s are hypogonadal (R).
Let’s take a deeper look. The estimated prevalence of hypogonadism varies widely (between 2.1% and 38.7%) in middle-aged and older men, but that number increases to approximately 50% among individuals with diabetes or obesity (R). Hypogonadism is often under-reported because not everyone goes to the doctor or the doctor doesn’t even test for it.
It would seem that the high number of men with low testosterone is due to comorbidities, such as obesity and diabetes, instead of age itself.
This brings us to our next point.
#2 Testosterone levels are decreasing, but it doesn’t have to
Testosterone decline with age
You might have seen the common statistic that testosterone declines by 100 ng/dL every ten years or 1% every year after the age of 35 (R).
The following study (which included over 10,000 healthy males aged between 3 and 101 years) showed that testosterone peaks (on average) at 15.4 (range of 7.2–31.1) nmol/L at 19 and then falls in the average case to 13.0 (6.6–25.3) nmol/L by age 40 years. After that, they found no further decline (R).
In reality, only 0.6% of healthy men or 0.4% of lean men developed functional hypogonadism (R).
Testosterone dropping with age is a result of comorbidities, poor sleep, stress, malnutrition, etc.
Testosterone decline over generations
Based on this 2020 study testosterone levels of men between 2016 to 2019 are on average 2-3nmol/L (57-87ng/dl) lower compared to men of the same age in 2006-2009 (R).
The main explanation for this is the increased consumption of ultra-processed foods, and increased amounts of environmental toxins (plastics, pesticides, etc.) and xenoestrogens.
#3 Free testosterone as the best marker for hypogonadism
This 2001 study showed that testosterone decreases with age, but free testosterone drops much more (R). This is why someone might have normal testosterone, but still have hypogonadal symptoms.
#4 Sleep apnea lowers testosterone
Sleep apnea is characterized by repetitive episodes of upper airway obstruction that occur during sleep and is associated with a complete (apnea) or incomplete (hypopnea) cessation of airflow. This is commonly accompanied by loud snoring and a reduction in blood oxygen saturation, followed by arousal, fragmented sleep, and daytime sleepiness.
The prevalence of sleep apnea in obese individuals is over 30% and 50-98% in morbidly obese patients.
In the table below, you can see that the more severe sleep apnea is, the lower testosterone is.
CPAP therapy significantly increased oxygen saturation and reduced nighttime arousals. According to this study, it also almost tripled testosterone levels and dramatically improved erectile function (R).
The two main mechanisms how sleep apnea lower testosterone is by causing hypoxia and sleep fragmentation (R). Obesity is one of the biggest reasons for sleep apnea.
On the flip side, testosterone improves sleep quality, but only when cortisol is low (R). Herbs like Ashwagandha will help to increase testosterone and lower cortisol and improve sleep quality.
#5 Obesity and low testosterone
Globally, the prevalence of obesity has nearly tripled since 1975 and it’s predicted that one in five adults will be obese by 2025 (R).
In 2016, the World Health Organization (WHO) data showed that 39% of the world’s population is overweight and 13% are obese.
Obese individuals (with a BMI >30 kg/m2) have an 8.7-fold increased risk of secondary hypogonadism, while about 75% of subjects with severe obesity (BMI > 40 kg/m2) have hypogonadism (R).
Men with a BMI of 35–40 kg/m2 can have up to 50% less free and total testosterone when compared to age-matched peers with a normal BMI (R).
A few mechanisms of how obesity contributes to low testosterone include:
- Elevated inflammation.
- Insulin resistance.
- Leptin resistance.
- A drop in SHBG.
- Elevated testicular temperature.
- Sleep apnea.
- Elevated aromatase.
- Gut dysbiosis and an increase in endotoxin production and leaky gut.
- Accumulation of fat-soluble endocrine-disrupting chemicals (R).
- Abnormally increased expression and activity of enzyme 11b-hydroxysteroid dehydrogenase type 1 (11b-HSD-1) in adipose tissue which activates cortisol. This leads to a high cortisol-to-testosterone ratio.
Low testosterone in turn promotes weight gain.
#6 Diabetes lowers testosterone
Men with diabetes have lower levels of testosterone than men without (R). (as you can see in the graph on the right)
In addition, diabetics tend to have elevated estradiol levels despite lower testosterone levels (R).
Testosterone and DHT are protective against diabetes
Men with diabetes and untreated low testosterone had significantly higher mortality over four years, relative to those with normal testosterone, or those who received TRT (R).
Testosterone also protects against prediabetes (R). Men with higher testosterone were less likely to become prediabetic and progress to full-on diabetes.
Lastly, it’s been shown that higher levels of DHT are inversely associated with insulin resistance and risk of diabetes over the ensuing 10 years, whereas levels of T were not (R).
So make sure you optimize both testosterone and DHT.
👇8 most powerful ways to boost DHT👇
#7 Poor sleep quality lowers testosterone
Just 1 week of sleep restriction (limited to 5 hours) decreased testosterone by 10% to 15% in young healthy men (R).
Additionally, sleep disturbances reduced the testosterone rise overnight, only if REM sleep was compromised. The dark line is the sleep disturbance group and the light line is the normal rise in T overnight (R).
It’s not just total testosterone, but also free testosterone that’s negatively affected by sleep restriction (R). In the graph below, you can see that men who slept 8-9 hours had the highest testosterone and there was no benefits to more sleep.
Finally, TRT has been shown to significantly improved sleep disturbance in hypogonadal men (R). Sleep loss lowers testosterone, but optimizing your testosterone can help to improve sleep quality.
#8 Stress lowers testosterone
Stress has been shown to lower GnRH, LH and FSH release, impair testicular function and reduce androgen receptors (R).
A study published in the journal Psychoneuroendocrinology in 2013 found that chronically stressed men had 50% lower testosterone levels than those with lower levels of stress.
A 2005 study published in the journal Psychosomatic Medicine found that men who reported high levels of work-related stress had 20% lower testosterone levels compared to lesser-stress men.
Keep in mind that there are many kinds of stressors, with 3 main categories of stress, namely immunologic (e.g. endotoxin for the gut), metabolic (e.g. hypoglycemia) and psychological. All three can increase cortisol and lower LH and testosterone (R, R).
#9 Hypothyroidism and low testosterone
32.9% of patients with hypothyroidism also have hypogonadism (R).
Thyroid hormone T3 is intricately involved in testosterone production.
Men with primary hypothyroidism have subnormal responses of luteinizing hormone (LH) to gonadotropin-releasing hormone (GnRH). The Leydig cells also contain T3 receptors, so T3 directly stimulates the testes to produce testosterone.
Men with hypothyroidism tend to have lower total and free testosterone, low testosterone-to-estradiol ratio, low DHT and higher cortisol and prolactin (R).
Low testosterone in hypothyroidism is due to (R):
- Reduced uptake of LDL-C by the Leydig cells. Testosterone is created from cholesterol.
- Reduced conversion of progesterone to testosterone
- Higher rate of conversion of testosterone to estradiol
- A decrease in serum triiodothyronine
Varicocele is a condition where the veins in the scrotum become enlarged, causing pain and discomfort, and it can also affect the production of testosterone.
Varicoceles affect 15%–20% of the general male population and up to 40% of infertile men (R).
The first study in 1975 reported that 10 out of 33 (30%) men with varicoceles had decreased testosterone levels and erectile dysfunction, and both symptoms improved in those men after varicocelectomy (R).
In 2011, Tanrikut et al. demonstrated that men with varicoceles have reduced testosterone levels. Of the men with low testosterone, 79% regained normal testosterone levels after varicocelectomy (R).
A few reasons why varicocele might cause low testosterone include venous stasis, increased testicular temperature, oxidative stress, and a resulting toxic environment.
#12 Opioid-induced low testosterone
This counts for opioid-based pain medication, sleep medication, premature ejaculation meds and narcotic use.
In the following graph, you can see all the different mechanisms of how opioids cause low testosterone and sexual dysfunction.
Most SSRIs lower testosterone for a variety of reasons, namely by increasing prolactin, serotonin and cortisol and being directly toxic to the testicles (R).
SSRIs may cause sexual dysfunction in 40% to 65% of individuals and as many as 50% of people do not discuss these issues with healthcare providers! (R) So the number might be ever higher.
Specifically, SSRIs (which inhibit serotonin reuptake (inhibit SERT)) have the highest prevalence of side effects.
According to this study, The incidence of sexual dysfunction with SSRIs and venlafaxine (an SNRI) were high ranging between 58% and 70% – fluoxetine (57.7%), sertaline (62.9%), fluvoxamine (62.3%), venlafaxine (67%), paroxetine (70.7%), and citalopram (72.7%).
The newer 5-HT2 blockers (8% nefazodone and 24% mirtazapine) have a much lower incidence of sexual dysfunction. And lastly, Moclobemide, a reversible MAOI, (3.9%) has the lowest incidence of sexual dysfunction (R).
#14 Overexercising can lower testosterone
Exercising (e.g. long distance running) a lot can lead to lower testosterone and higher levels of hypogonadal symptoms (R).
In the graph below, the gray marks are the endurance group and the black marks are the control group.
Some people can buffer the stress better than others, so the distance required that will lower testosterone will differ for each individual.
Poor sleep, eating nutrient-poor foods, not eating enough, stress, etc, will drop your testosterone even faster.
For the general population, 30-45min of aerobic exercise 3-4 times per week can increase testosterone.
#15 Excess alcohol consumption can lower testosterone
Alcoholics have (R):
- lower testosterone
- higher estrogen
- a higher prevalence of sexual dysfunction and mood disorders and
- smaller testes than non-alcoholics.
In this study, researchers gave students the equivalent of a pint of 86-proof whiskey per day for 30 days (R). They were hypogonadal at the end of 30 days.
I know a pint of whiskey per day is a lot, but even smaller amounts can over time have a negative effect on your testosterone levels.
Alcohol lowers testosterone by:
- Causing liver damage
- Depleting the body of B-vitamins
- Increasing aromatase
- Directly damaging the testes
- Contributing to gut dysbiosis
- Inhibiting key steroidogenic enzymes, such as 3β-hydroxysteroid dehydrogenase (3β-HSD) and 17-ketosteroid reductase. These enzymes convert pregnenolone to progesterone and androstenedione to testosterone.
- Enhancing the production of radical oxygen species that suppress the expression of the steroidogenic acute regulatory protein (StAR). StAR is the rate-limiting enzyme that transports cholesterol into the mitochondria of the Leydig cells to be converted to pregnenolone.
But we all like to indulge a little bit. Here is the stack that I use to speed up alcohol clearance from the body and protect the liver and testes:
- 5-10g taurine
- 300-600mg dihydromyricetin
#16 Low SHBG is the cause of low testosterone
Most people think that they should lower SHBG to increase free testosterone. But low SHBG is actually a sign of metabolic syndrome and liver dysfunction. People with liver dysfunction and low SHBG often also have low total and free testosterone.
In this graph, you’ll see that as BMI goes up, SHBG and total testosterone drop.
As SHBG drops, so will testosterone (R).
You don’t necessarily want to maximize SHBG, but you want to make sure your liver and thyroid are optimal. The liver produces SHBG and T3 stimulates the liver to produce more SHBG.
Optimal liver and thyroid function will ensure optimal SHBG and testosterone levels.
#17 Type 1 diabetics have lower free testosterone
Men with type 1 diabetes that have their blood sugar controlled with insulin have normal testosterone, but low free T and high SHBG (R).
Insulin is one of the most powerful suppressors of SHBG and low insulin will result in high SHBG.
If you want to check your insulin, check fasting insulin as well as C-peptide. C-peptide will show you how much insulin you secreted over a 24-hour period.
#18 Testosterone and bone mineral density
Between 16 and 30% of men with osteoporosis are hypogonadal (R).
In older men, DHT was inversely associated with hip fracture risk and SHBG was positively associated with hip fracture risk, while testosterone was not (R).
#19 Testosterone, CVD and stroke
Roughly 66.3% of patients with ischaemic stroke have hypogonadism (R).
A study in Denmark found that low testosterone was a significant risk factor for post-stroke mortality. At six months, free and total testosterone were significantly higher in surviving patients: 14.7 vs 10.1 nmol/L, and 13.2 vs 10.5 pmol/L respectively (R).
Higher testosterone meant higher chances of surviving after a stroke (R).
Men with higher testosterone or DHT have a reduced risk of stroke (R).
#20 Testosterone and medical bills
Low testosterone is costing you more than if you were healthy!
A large epidemiological study conducted in Germany of 2023 men, found that men with low testosterone (7.84 nmol/L on average) had:
- A significantly higher number of outpatient visits per year and
- Significantly higher yearly outpatient costs,
Relative to men with high testosterone (16.28 nmol/L on average) (R).
As you can see in the table below, the hypogonadal group (HG) had an average of $11,957 medical bill vs $7,088 of the normal men.
In an analysis of a US insurance database (of 4269 men), total yearly costs related to cardiovascular comorbidities were almost doubled in men with hypogonadism, relative to those without ($1453 vs $767) (R).
#21 Weight loss and testosterone
Weight loss has been shown to increase testosterone. You can expect a 100ng/dl increase for each 10% of body weight that you lose. If you optimize your diet and lifestyle, you can expect even greater increases.
#22 Testosterone and erectile dysfunction
Guay et al. found that roughly 36% of men with ED were hypogonadal (R). Keep in mind that the hypogonadal range is around 250-300ng/dl. So it’s likely that 85% or more of men with ED have testosterone under 500ng/dl.
#23 Testosterone and prostate cancer
Men with high testosterone are protected against prostate cancer.
In 2006, Morgentaler et al (R) found prostate cancer in:
- 21% of men with testosterone <250 ng/dl compared to only
- 12% of men with testosterone levels >250 ng/dl.
In 2013, Rastrelli et al, found that low serum testosterone (defined as <240 ng/dL) was an independent predictor for prostate cancer.
Shin et al (R) found prostate cancer in:
- 38.9% of men with testosterone less than 385ng/dl compared to
- 29.5% of men with testosterone >385ng/dl.
👉 Read the full article: Testosterone and prostate cancer: we’re been lied to
>1000ng/dl Testosterone: My Step-by-Step Guide on How I Do It Naturally!