Testosterone Explained

Ziven Testosterone is a science-based, state-of-the-art testosterone restoration program that helps men GET IT BACK - reclaim their energy, sexual desire, and masculinity.

We’ve produced the following resources to help you understand just how vital testosterone is to a man’s health. If you prefer reading, skip the video below.




Although it’s often called the “male” hormone, both men and women have testosterone. It’s critical for women’s health, but their level is much lower, and it plays a minor role compared to its vital function in men.

During puberty, testosterone drives the process of making a boy’s body into a man’s, including muscle building, hair growth, and sexual development. 

In adulthood, it influences our energy level, body composition, and overall health. It can even affect our behavior. 

Having too much or too little testosterone causes problems, so it’s important to know your level of it. To find what our level is, we measure the two types of testosterone in our blood: total testosterone and free testosterone. 

Total testosterone is how much testosterone is bound to proteins in the blood – albumin and SHGB, or sex-hormone binding globulin. This is the better biomarker indicator to measure in men.

Testosterone that is not bound to these proteins is free testosterone. This is the better biomarker for women, because it measures the availability of testosterone in their bodies.


Low testosterone leads to very noticeable problems in men. A number of these relate to sex: low sex drive, difficulty getting and maintaining an erection, low semen volume, and smaller testicular size. Other signs you don’t have enough testosterone include hair loss, fatigue, loss of muscle mass, increased body fat, decreased bone mass, mood changes, memory problems, and diminished red blood cell count. You won’t necessarily experience all of these symptoms if your testosterone level is low, but as we’ll see a bit later, you will lose more and more testosterone as you age, so eventually you may experience all of them. Let’s take a look at each symptom.
Do you have low testosterone?

Low Sex Drive

Testosterone is key to maintaining a normal sex drive, or libido. Most men will experience a decline in their libido as they age, but if you have low testosterone, your desire to have sex will fall off sooner and more steeply.

Difficulty with Erections

Beyond helping us want to have sex, testosterone is essential to being able to have it. A man’s ability to have an erection isn’t caused directly by testosterone. Instead, testosterone stimulates receptors in the brain that produce a molecule called nitric oxide. 

Nitric oxide helps trigger a series of chemical reactions that are necessary for erections, including opening arteries that increase blood flow.

If you don’t have enough nitric oxide, this chain of events leading to an erection is stymied. Other health problems, like diabetes, high cholesterol, depression, and so on, can play a role in erectile difficulties, but not having enough testosterone is a big factor. 

Low Semen Volume, Smaller Sex Organ Size

Semen is the milky fluid that carries sperm during an ejaculation. Men who are low in testosterone produce less semen. They may also experience atrophy, or shriveling, of the penis, scrotum, and testicles. 

Muscle, Bone, and Hair Loss

Testosterone plays a vital role in building muscle, growing and maintaining hair, and keeping bones strong. 

Without adequate testosterone, your muscle mass may decrease, although muscle strength and function won’t necessarily be affected. 

Low testosterone can cause hair loss all over one’s body, beyond what would be expected with age or genetic factors. 

And making sure our bones stay strong as we age can help prevent not just bone loss, or osteoporosis, but also fractures that can badly affect our quality of life. 

Increased Body Fat

Low testosterone increases our body fat, which in turn makes it harder for our bodies to produce testosterone. If we don’t increase our testosterone level in the face of this feedback cycle, it will continue unchecked, potentially leading to gynecomastia, or enlarged breast tissue, which is thought to occur when there’s an imbalance between testosterone and estrogen in men.

Decreased Red Blood Cell Count

Research published in the Journal of the American Medical Association has shown a link between low testosterone and an increased risk of anemia. Anemia is caused by a deficiency of red blood cells and also a lack of hemoglobin, which carries iron, in the blood. 

Mental and Behavioral Changes

As we get older, our cognitive functions, especially memory, will decline. Some doctors believe this may be linked to declining testosterone levels in men. A recent study in the Journal of the American Medical Association linked testosterone supplementation with improved memory in men who had low testosterone levels. 

On top of worsening memory, testosterone deficiency can cause fatigue and a lack of motivation. This in turn can make you less likely to exercise, which can result in adding more body fat, which decreases testosterone production. 

Do these symptoms sound depressing? A suboptimal testosterone level may actually cause depression, as well as irritability and a lack of focus.



The normal testosterone level for you depends on your age, and whether or not you are having symptoms of low testosterone. 

For men, total testosterone peaks at around 1,100 nanograms per deciliter (ng/dL) at age 20. After that the level steadily declines. Although below 300 ng/dL is commonly considered the cut-off point, a man can have symptoms of low testosterone at higher levels.



The symptoms mentioned above can certainly indicate low or decreasing testosterone, but the first sign you’re likely to notice as you age is difficulty maintaining lean body mass. It’s harder to keep weight off, to stay as fit as you used to be, even with the same amount of exercise.

An example of this is how players in the NFL are usually more lean when they join the league than they are four or five years later. 

For every pound of muscle you lose, you no longer burn 50 calories when you’re at rest. Pound after pound, these unburned calories add up, and even if you’re exercising and eating as you did before, you’ll accumulate more fat. 

Men store fat mostly in the abdomen as deep visceral fat. This fat isn’t passive; it is actually an organ, a hormone-producing endocrine gland. It produces estrogen and harmful inflammatory markers that can increase your risk of cancer significantly, as shown in a Michigan State University study in 2017. 

Negative feedback loop

With this fat now producing more estrogen in your body, a negative feedback loop is established that actually inhibits testosterone production further. Your brain measures the amount of estrogen in your body to determine if it needs to make more testosterone, so when it detects more estrogen, you make less testosterone, which in turn means more deep visceral fat, and more estrogen, and so on.

This process is natural and normal, and most men accept it as their fate in life to lose their vitality as they age. Doctors will usually tell you your testosterone level is in the normal range even if it’s declined over 70% since you were 20. And even if it’s low for your current age relative to other men, it may still be considered “normal” compared to a wide range of men in the general population. 



You don’t have to live life with low testosterone. 

Millions of men supplement their testosterone levels safely and affordably, reclaiming the vigor of past years. 

We know not having optimal testosterone can make a man weak, forgetful, uninterested in sex, and at a higher risk for health problems. 

But the good news is it’s relatively easy to get it back—to bring your testosterone level up high enough to counteract the effects of not having enough.

With an optimized level of testosterone, you can:

  • —improve your metabolism
  • —lose body fat
  • —increase your lean body mass, which means more calories are burned at rest
  • —reduce your total cholesterol and increase your “good” (HDL) cholesterol
  • —help prevent plaque formation in your arteries, reducing your risk of stroke and heart attack
  • —increase your bone mineral density for stronger bones
  • —regain libido, energy, and memory function
  • —improve mood and outlook


To do all of this, you need to have at least a normal level of testosterone for your age, but even better, an optimal level, which may be higher than what your doctor tells you is “adequate.”




Of all of the methods of administering testosterone, we believe the two most effective are injections and a topical cream. They are also more convenient than many other methods because they can be self-administered in the privacy of your home. 

The testosterone in injections and cream is the same, and both methods have been used safely for decades. Here are the pros and cons of each. 



The main advantage of using a cream to increase your testosterone level is that it is easy to apply compared to self-injection, which some people may not feel comfortable with. If you have a bleeding disorder or are taking blood thinners, creams are safer to use. 

Applying cream twice a day means your testosterone level is very stable through the week, compared to injectable testosterone, which can result in peaks and troughs in your level. 

And while both injectable and cream forms of testosterone can lower bad cholesterol levels, cream tends to have a greater effect.

Cream is best applied to the scrotum. This is for several reasons: there are a lot of blood vessels there, the skin is thin, and it’s usually protected from contact with others. 

Several cons of using cream, though, result from its taking 3-4 hours to be completely absorbed. You must wash your hands thoroughly so you don’t transfer it to another person, especially a woman or child. You should not have sexual contact with anyone during that time either. 

Also, sweat can interfere with full absorption of the cream, so working out or doing something outdoors on a hot day can reduce its effectiveness. 

Cream is also implicated in accelerated hair loss in men who have male pattern baldness or pre-existing thinning of the hair and a receding hairline. 

Lastly, you have to remember to apply the cream twice daily to maintain a stable testosterone level. 


Pros and cons of topical testosterone cream


Injecting yourself with testosterone has advantages over topical cream. 

Injections once or twice a week are more convenient than twice-daily applications of cream. You also don’t have to worry about accidentally transferring testosterone to others. 

If you have male pattern baldness, or pre-existing thinning of hair and a receding hairline, injectable testosterone is less likely to accelerate hair loss. 

The biggest hurdle for some men with injecting testosterone is the process of administering it to themselves. The injection site is on the thigh, a bit to the outside of the middle of the leg. While it’s not hard to do, and is completely safe when done as directed, it may take a while to get used to doing it. 

The injections are usually painless, but they can cause minor bruising and bleeding even when done correctly. Some men experience soreness as well, which generally stops occurring after a few times.

Because doses are administered once or twice a week, your testosterone level will peak right away, then decrease steadily until your next dose. A small percentage of patients feel this variation, but most people don’t.

Pros and cons of topical testosterone cream


One potential side effect of testosterone supplementation is the reduction, or even elimination, of your body’s natural testosterone production. 

Your body converts some of the testosterone you produce into estrogen. Supplemental testosterone means more estrogen is made. In response to this rise in your estrogen level, your body will decrease, or even shut down, testosterone production.

When this happens, your testicles will begin to shrink. You can prevent this by taking a pill, called an estrogen blocker, that helps prevent conversion of some of the testosterone to estrogen, and keeps your body’s production of testosterone going. 


Now that we’ve covered testosterone replacement therapy in depth, we hope you feel prepared to begin treatment, or continue it, with full confidence that it is right for you. 

We are constantly reviewing new research and attending medical conferences to stay on top of the latest findings in testosterone replacement therapy and inform our users of them. 

We believe in empowering our clients to optimize their health with state-of-the-art medical knowledge and best-in-class supplementation products. 

Our goal is to help you enjoy all the benefits of restoring your body’s testosterone to its youthful levels: to bring you optimal health and vitality so you can live an optimal life.