Testosterone: The Ultimate Guide to the Key Male Hormone

Written by: Christine VanDoren, nutritionist

Fact checked by: SaVanna Shoemaker, MS, RDN, LD

Testosterone: The Ultimate Guide to the Key Male Hormone

The sex hormone testosterone plays a vital part in the maturation and health maintenance of men. As a sex hormone, it is responsible for facilitating sexual maturation and the development of what are deemed to be “physically masculine” characteristics, as well as increasing sex drive.

In this article, we will discuss exactly what testosterone does and why it’s important for some people, namely men, to have sufficient levels of it. The effects of having healthy levels of testosterone will also be discussed, along with ways to promote testosterone production through the use of natural lifestyle changes if this happens to be the case for you.

What is Testosterone?

Testosterone is the main male sex hormone, which is responsible for regulating several important processes in a man’s body. 

Its most important functions are related to reproduction and sexual development. Testosterone regulates a man’s sex drive (or libido) and facilitates the production of sperm cells (known as spermatogenesis), both of which affect overall fertility in men. Testosterone is what also allows for sex differentiation between a male and a female, as well as the enlargement of the penis and testes during puberty in males.

Beyond the male reproductive system, testosterone regulates various other physiological factors such as bone density, muscle mass, fat distribution, and the production of red blood cells. This is likely because greater muscle mass and higher hematocrit are associated with masculinity. Exclusively in men, testosterone is also responsible for regulating secondary male characteristics such as vocal changes and hair growth in certain areas of the body.

Although it is known as the main male sex hormone, testosterone is also produced in a woman’s ovaries and adrenal glands, albeit in significantly smaller amounts than estrogen.

Regardless, testosterone can have very similar effects on a female in terms of libido regulation and muscle mass, but obviously to a lesser extent. 

Testosterone Production

The process of testosterone production starts in the hypothalamus and pituitary gland. 

The hypothalamus first releases gonadotropin-releasing hormones, which in turn trigger the release of luteinizing hormones within the pituitary glands. These hormones then travel to the man’s testicles, where they stimulate both the production and release of testosterone throughout the body. 

As the amount of testosterone in a man’s body increases, the production of gonadotropin-releasing hormones is slowed down to maintain healthy levels of testosterone and prevent too much of it from being made.

Abnormal testosterone levels occur if the hypothalamus, pituitary glands, or testicles (or ovaries in women) are not working properly in this regard. If this is the case for either the pituitary glands or hypothalamus, then either too little or too much of either gonadotropin-releasing hormones or luteinizing hormones are being produced. 

Although the process of producing sex hormones is similar in women, the luteinizing hormones that females produce more often produce estrogen and progesterone instead. These hormones produce very small amounts of testosterone in women, but usually not enough to lead to the development of male characteristics.

Testosterone and Physical Health

Effects on Bone Density

The growth and maintenance of bones are greatly influenced by testosterone, which acts directly on osteoblasts to promote the formation of bone material. It also affects bone metabolism to some extent as it influences certain growth factors, which help maintain the structure and quality of the bones by balancing the process of building and breaking down bone material as needed.

Effects on Muscle Mass

Because more developed muscles are considered a secondary male characteristic compared to females, testosterone is found to increase muscle mass by increasing the production of muscle proteins in the body. With more muscle proteins being synthesized thanks to testosterone, it becomes easier to contract and relax muscles to resist greater amounts of weight. 

The results of one particular study involving long-term testosterone supplementation in older men suggest this. The participants who were given the experimental testosterone supplement showed significant increases in both muscle mass and muscle power, especially when compared to the participants who only received the placebo. 

Effects on Fat Storage

Testosterone is noted to accelerate the rate of metabolism in body cells. Relating back to how testosterone plays a role in muscle growth, increased levels of this hormone allow more excess fat to be burned away in order to make room for more muscle material. 

In one study, the presence of testosterone is shown to impede the growth of body fat and reduce the amount of fatty tissue being produced in mice. In contrast, lower metabolism levels led to an increase in fat production and growth as there is not enough of the hormone to control it, as well as in the mice with higher testosterone levels.

However, it should be noted that this study involved the use of mice and not human males due to the process of castration being involved. Therefore, whether or not this also applies to human males is left up for debate.

Effects on Red Blood Cell Production

Researchers have discovered that there is also a correlation between the amount of testosterone in a man’s body and the production of red blood cells, also known as erythropoiesis. 

The results of one study suggest that the presence of testosterone stimulates the production of the hormone erythropoietin (EPO) in the kidneys, which in turn stimulates red blood cell production within the bone marrow. This chain reaction leads to slightly higher hemoglobin and hematocrit levels, even after EPO levels slowly decrease back to the baseline level after six months of testosterone therapy.

Testosterone and Mental Health

Not only does testosterone affect your body, but it also affects your mind.

In terms of mood regulation and self-perception, having sufficient levels of testosterone is shown to reduce the severity or frequency of symptoms often associated with mental health challenges.

Having healthy levels of testosterone can also help people be more equipped to deal with daily stressors. It's been noted that those with normal testosterone levels are also known to appear more confident and assertive without being aggressive.

Fluctuations in Testosterone

As men grow older, the amount of testosterone their bodies produce begins to wane over time, starting in their mid-30s. This decreased production of testosterone can lead to changes in sex drive), muscle mass and strength, and even the regulation of emotions and cognition in some people.

Healthy testosterone levels are also attributed to healthy red blood cells, which is essential for proper circulation of nutrients through the blood and normal amounts of fat in the body.

Fortunately, there are multiple ways to promote testosterone production. These can range from healthy lifestyle choices and changes in physical activity or diet to the use of supplements that support testosterone production.

Testosterone Supplements

Testosterone supplements help to maintain healthy testosterone levels in a person’s blood by promoting more testosterone production. Please note that testosterone supplements do not actually contain any of the hormone testosterone. Testosterone replacement therapy, which provides bioidentical, synthetic testosterone, is available via prescription only and must be managed by a qualified healthcare provider.

The primary purpose of testosterone supplements is to foster healthy aging. These include changes in sexual drive, physical changes in terms of muscle mass and strength in men, and even emotional changes. 

Although testosterone supplements are considered popular and “natural” alternatives, some research suggests that there is no solid proof that these supplements are very effective in either men or women. Only 24.8% of the products observed in one study had scientific data to support such claims, and some data suggests that they negatively impact testosterone production. However, evidence hinting at even a small possibility of testosterone supplements working means they may still be worth considering for some people.

Like several other dietary supplements, testosterone supplements come with the possibility of some mild side effects such as acne, dizziness, and stomach cases. Fortunately, these mild side effects are fairly uncommon but still easy to treat if they should occur. However, some people using testosterone supplements have experienced more severe adverse reactions, such as abnormalities in the kidney and liver, as a result of these supplements’ ingredients. As always, it's important to consult a healthcare professional before adding any new supplements to your routine.

Natural Ways to Support Testosterone

Of course, testosterone supplements are not for everyone. If you prefer to support testosterone production in more natural ways, there are some steps you can take that don’t require taking testosterone supplements.


Some researchers have discovered that due to its connections with the regulation of muscle mass, men can promote testosterone production through resistance training exercises, such as weightlifting. 

The extent of testosterone production in this way heavily depends on how heavy the weights being used are. Higher volumes lead to higher metabolic demand, which in turn makes it more likely to promote testosterone production as higher levels of this hormone allow for more fat to be burned as energy.


Testosterone production is believed to be linked to protein intake to some extent. It is hypothesized that the more protein products you consume, such as red meats and seafood, the more testosterone your body will be able to produce. 

However, one study concluded that diets that are extremely high in protein do not help at all. In fact, diets consisting of more than 3.4 g/kg of body weight per day actually decrease testosterone levels, while diets consisting of 1.25 to 3.4 g/kg of body weight per day do not negatively affect testosterone levels.

This does not mean you should avoid protein-rich foods if you’re looking to promote testosterone production. Rather, you should ensure that your protein intake isn’t exceeding 3.4 g/kg of body weight per day.

In contrast, diets that are high in dietary fat appear to increase resting testosterone concentrations, especially in men who also do resistance training. This is likely because the additional fat requires more testosterone circulating in the bloodstream to metabolize it into additional energy while still maintaining healthy fat distribution throughout the body. Although fat should not be considered an optimal fuel source for everyone, that doesn’t change the fact that a high-fat diet appears to have a positive effect on circulating testosterone levels.

If you plan to go on a high-fat diet to increase testosterone levels, it is recommended to eat foods that are high in natural fats as opposed to more unstable fats, such as corn oil or soybean oil used for frying and in processed meals and snacks. Healthier choices include nuts and seeds, avocados, fatty fish like salmon and tuna, eggs, and unprocessed meats.

Lifestyle Changes

Aside from diet and exercise, there are also some other things to consider that can help maintain healthy testosterone levels. 

Although mental stress, in general, is unavoidable in life, placing yourself in too many stressful situations can inhibit testosterone production. For more acute instances of stress, you can simply utilize simple relaxation techniques such as visualization or meditation. In more severe or chronic cases, you can speak with a licensed therapist to create a stress management plan that works for you.

In relation to managing stress, better sleep quality can also help you maintain sufficient levels of testosterone, especially when combined with exercise. Some good ways to improve the quality of sleep at night are by participating in physical activity during the day and avoiding caffeinated products or alcohol a few hours before you go to bed.

Not only can alcohol make it harder for you to fall asleep at night, but drinking, in general, has been found to be associated with lower testosterone levels. In one study, heavy drinkers were found to have less testosterone than those who didn’t drink at all. This is because too much alcohol can reduce function in the testicles, thereby reducing testosterone production. As such, it is recommended to avoid or at least heavily restrict alcohol intake if you’re hoping to support testosterone levels.


Overall, testosterone, as the main male sex hormone, plays a vital role in regulating various processes within males (and females, to a significantly smaller extent) in regard to both reproduction and overall physical health, which is why it is crucial for men to maintain healthy testosterone levels. 

Of course, this isn’t easy for all men. Fortunately, there are various options and natural lifestyle changes that may help men promote the production of this important hormone.

Before making any substantial lifestyle changes, such as beginning testosterone supplements, it is very important to consult a medical professional for personalized advice, as some methods may not be suitable for everyone. Even if they decide that testosterone supplements aren’t right for you, there are still many easy and natural ways to ensure that you benefit from having healthy levels of testosterone in your body.


  1. Bachman, Eric et al. The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences vol. 69,6 (2014): 725-35. doi:10.1093/gerona/glt154.
  2. DiNicolantonio, James J, and James H O'Keefe. Open heart vol. 5,2 e000898. 26 Sep. 2018, doi:10.1136/openhrt-2018-000898.
  3. Koh, Kyungmi et al. Korean Journal of Family Medicine vol. 43,6 (2022): 381-387. doi:10.4082/kjfm.21.0173.
  4. Nassar, George N, and Stephen W Leslie. StatPearls, StatPearls Publishing, 2 Jan. 2023, https://www.ncbi.nlm.nih.gov/books/NBK526128/.
  5. Nedresky, Daniel, and Gurdeep Singh. StatPearls, StatPearls Publishing, 26 Sept. 2022, https://pubmed.ncbi.nlm.nih.gov/30969514/.
  6. Patel, Premal et al. World Journal of Urology vol. 37,7 (2019): 1449-1453. https://doi.org/10.1124/pr.117.014092.
  7. Sebo, Zachary L, and Matthew S Rodeheffer. Molecular Metabolism vol. 44 (2021): 101141. doi:10.1016/j.molmet.2020.101141
  8. Shigehara, Kazuyoshi et al. Journal of Clinical Medicine vol. 10,3 530. 2 Feb. 2021, doi:10.3390/jcm10030530
  9. Storer, Thomas W et al. The Journal of Clinical Endocrinology and Metabolism vol. 102,2 (2017): 583-593. doi:10.1210/jc.2016-2771.
  10. Vingren, Jakob L et al. Sports Medicine (Auckland, N.Z.) vol. 40,12 (2010): 1037-53. doi:10.2165/11536910-000000000-00000
  11. Whittaker, Joseph. Nutrition and Health vol. 29,2 (2023): 185-191. doi:10.1177/02601060221132922
  12. Xiong, Xiaofan et al. Journal of Cellular and Molecular Medicine vol. 26,2 (2022): 354-363. doi:10.1111/jcmm.17085
  13. Zamir, Amit et al. ” Nutrients vol. 13,10 3375. 25 Sep. 2021, doi:10.3390/nu13103375
  14. Zitzmann, Michael. Andrology vol. 8,6 (2020): 1598-1605. doi:10.1111/andr.12867