What is Testosterone? The Basics and Production of Androgens
By Ali Kuoppala | Last reviewed Tue 25 September 2018
Medical Review by Dr. Stefano Pizzo, MD
Sadly, most guys who start optimizing their natural testosterone production, don’t really know how the hormone works and is produced in the first place. Even though the process is the exact thing that they’re trying to optimize, hack, fix, or whatever.
To put it simply, this is the most important thing you have to fully understand before you even begin to read anything about diet, supplementation, lifestyle changes, etc.
So pay close attention:
What Actually is Testosterone
Testosterone is the principal male sex steroid hormone. It belongs to the group of androgens, which simply means that it belongs to the group of other male hormones (DHEA, DHT, etc).
Testosterone is found in both men and women, but men have about 10 times more of it, and obviously men are the gender that benefits more of having high levels of the principal male hormone.
Testosterone – and many other androgens – are most known for their effects on sexual characteristics. Simply put, testosterone is the hormone that makes us men. It stimulates the growth of the penis and scrotum, is crucial factor in sperm production, strengthens vocal cords, increases the growth rate of body and facial hair, impacts body shape, controls fat distribution, and simply makes men more manly from the tops of our scalp, to the tips of our toes.
Oh, and it’s also anabolic. When testosterone molecules enter the androgen receptor sites in your muscle tissue, they trigger protein synthesis, and therefore growth of new muscle tissue. Similar effects take place in your bones. Testosterone molecules bind to the skeletal androgen receptors and increase the density, strength, and mineral uptake of them.
The above is also the reason why synthetic testosterone is the most sought after performance enhancing drug in many sports, especially in bodybuilding. It just makes you build muscle so much faster.
Many men also ask me why I’m interested in natural testosterone optimization, when I could just inject testosterone like almost all of the pro-bodybuilders do?
The reasoning for that is very simple: When you fill your body up with exogenous testosterone, your body declines its natural production of the hormone. Guess what happens when you stop using the exogenous T? That’s right, your body still won’t produce its own. And by the way, this is not only happening with freakishly huge amount of steroid usage, the same thing happens with those testosterone gels, creams, pellets, and patches that your kind doctor man is prescribing with a smile on his face.
So yeah, that’s testosterone, but how it is actually produced in the body? That’s what you’re about to find out next.
How Testosterone is Produced
A lion’s share of about ~95% of your testosterone is produced inside the ballsack, in the testicular leydig cells to be more precise. The remaining ~5% is synthesized from DHEA (precursor androgen) in the adrenal glands.
Obviously the molecule doesn’t just magically appear in the testicles, there’s a strategic cascade of events that leads to the production of the hormone. And like everything in the body, it starts from the brain.
Here’s how the natural “feedback loop” of testosterone production operates:
1. It all starts from the hypothalamus, which is an almond sized brain substrate that links your nervous system to the endocrine system. The first step of the process is simply when the hypothalamus releases a hormone called gonadotropin releasing hormone (GnRH). Keep in mind that this is the master hormone that starts everything.
2. GnRH then stimulates the pituiary gland, which is a small pea sized endocrine gland portruding from the bottom of the hypothalamus. When the gland is stimulated by GnRH, it releases two hormones: luteinizing hormone (LH) and follicle stimulating hormone (FSH). These are the gonadotropins, and this is exactly why they first hormone is called gonadotropin relasing hormone.
3. After the pituiary gland has released LH and FSH to the bloodstream, both of the hormones make their way from the brain, down to the ballsack. When they have reached their destination they enter the testicular leydig cells.
4. Inside the leydig cells, the following events take place: FSH starts the process of spermatogenesis, whereas LH – through an extremely complex process – converts cholesterol (at this point its actually already pregnenolone) into testosterone.
Ta-da! That’s how the big T is produced. But wait, why is it called a feedback loop?
Answer: After the fresh testosterone molecules are produced, your brain constantly monitors the amount of the hormone in blood, if it gets to be too high, it slows down the release and transportation of LH. And that’s how the loop is completed.
How Testosterone Excerts its Effects in The Body
Now the testosterone is freshly produced and your leydig cells release it to the bloodstream. What happens next? How does the hormone exert the effects?
It doesn’t just float around the blood for nothing. Right?
Well of course not.
Here’s what happens next:
1. As the fresh baby testosterone enters the bloodstream, it’s called “free testosterone”. This is because it’s literally free, as it’s not bound to anything yet. But then your liver also releases this carrier protein called sex hormone binding globulin (SHBG). And this is where things get complicated.
2. About ~98% of the fresh “free testosterone” is bound to either SHBG or albumin (another carrier protein), and when testosterone is bound to either one of these proteins, it cannot effectively enter cells anymore, and it has really hard time binding to the androgen receptors. Meaning that ~98% of the testosterone is not really that “active”. Simply put, the more of the carrier proteins (SHBG and albumin) you have in your bloodstream, the fewer testosterone molecules actually remain bio-available.
3. The remaining testosterone that isn’t bound to carrier proteins (free testosterone), freely circulates around your body, just waiting to be bound into a receptor. Then for example, let’s say that you’re lifting weights at the gym. Your androgen receptors in the muscle tissue activate and free testosterone molecules will be bound to the receptors. This is when the effects start to take place.
4. Once the free testosterone molecule is bound to androgen receptor, the receptor goes through a structural change, making it able to enter your DNA. Once it actually enters the DNA, the effects of testosterone finally take place. When it happens in your muscle tissue, you’ll get increased protein synthesis and muscle growth as a result. If this takes place in your face, your beard growth might increase, or facial bone structure might become more dense and angular, etc.
That’s that! Wherever there are androgen receptors in the body (muscle tissue, penis, bones, etc) free testosterone can bound to it and then enter DNA, and that’s where the hormone finally works its magic.
So that’s what testosterone is, how it’s produced, and how it actually works in the body.
Obviously the above is only a simplified version of the process. I think this quote from Christopher Walker (the author of TestShock) clarifies how complex the subject really is:
“The HPA axis, as a whole, is incredibly complex. There are (very very smart) people who devote their entire lives to studying its effects on the human body & behavior (ie endocrinologists, neuroscientists, etc) who still do not understand everything, nor will they ever.” –Christopher Walker