What Does Testosterone Affect? 

Testosterone is the most important male sex hormone that is naturally secreted in male’s body mainly by testicles (it is also produced in females but in much smaller amounts). Without testosterone males are not able to develop and maintain their reproductive system. Therefore, the hormone affects everything in the entire body and especially those things that make men different from women: reproductive organs and sexuality, behavior, muscle growth and hair growth on face, legs, chest and sometimes the back. If for some reason the body does not produce enough testosterone (the condition known as testosterone insufficiency, or hypogonadism), it leads to changes in sexual functions, behavior, muscle growth, etc.

How Testosterone Affects Behavior

Testosterone is associated with typical male behavior: dominant and competitive, and indeed it was scientifically proven that low testosterone levels in men lead to negative changes in mood: depression, irritation, loss of interest, lack of energy, etc. Men with low testosterone are less active and decisive, more pessimistic, and also act less protective of women. Another behavioral aspect testosterone is responsible for is aggression.

How Testosterone Affects Aggression

It was indicated in many studies that the level of testosterone in men correlates with the level of aggression: the lower testosterone is, the less aggressive is a male. It has been noticed that testosterone increases anger and hostility. On the other hand, the matter is still being studied and the correlation between testosterone level and aggression is not linear and sometimes not evident. In addition to that it has to be noted that the hormone testosterone is just one of the multiple chemical and environmental factors that influence the nervous system, and it is not only testosterone that is responsible for aggression.

How Testosterone Affects Muscle Growth

Hormone testosterone is involved in many biological processes in the body including those that affect muscle growth and fat loss. First, testosterone interacts with cells inducing them to produce more protein; second, the hormone causes the increase of growth hormones; third, it increases the tissue growth in general by interacting with neurotransmitters. That is why testosterone is widely used in bodybuilding to induce muscle growth. The most common way to use it is to inject testosterone (in ester form) intramuscularly; other ways include capsules and cream. It is important to mention that the increase of testosterone within the normal level (from low to normal or high) would not affect the muscle growth although it would bring changes in mood and sexuality. Only substantial increase of testosterone level can considerably increase muscle bulk.

How Testosterone Affects and Changes Face 

Testosterone is responsible for more masculine, strong and dominant appearance in men (as well as in women). However, facial features stop developing after puberty, so testosterone injections or pills won’t make a difference, except that it may increase fat in face and in such a way make a man look more masculine. Besides that, the hormone incites growth of facial hair (on neck, cheeks, upper lip and chin) and makes them thicker and darker than hair on the head. Although sometimes men who use testosterone may notice unusual hair loss. The unpleasant side effect of testosterone is that it makes skin oily by increasing oil secretion and, therefore, causes acne.