Testosterone is an androgen, the most important male hormone when it comes to reproductive and sexual health. Basically, it is what men are made of. Testosterone gives men deep manly voices, scruffy facial hair, large muscles. It’s entirely responsible for turning boys into men by stimulating the growth of the male genitals, fueling libido and sperm production, as well as sustaining normal erections.
Outside sexual health, testosterone plays a role in the production of red blood cells, protecting the brain and boosting mood. However, the joys of testosterone don’t last forever. Levels begin to peak at around age 18, continuing throughout a man’s 20’s. At around age 40, testosterone levels start to fall by about 1% per year.
As men enter their 50s, their levels become low enough to cause symptoms of andropause, which is estimated to affect 5.6% of men between ages 30 and 69, and 18% of men aged 70 and above or 5 million men in the U.S.
Although testosterone levels decline naturally as a man ages, there are some factors that can contribute to the process. These include:
- Injuries and infections
- Steroid use
- Chemotherapy or radiation
- Pituitary dysfunction
- Inflammatory diseases like sarcoidosis
- Drugs used to treat prostate cancer or benign prostatic hyperplasia
- Kidney failure
- Psychiatric disease
- Liver cirrhosis
- Chronic stress
- Too much iron in the blood, a condition called hemochromatosis
Often, the top two symptoms that are worrying enough to warrant a visit to the doctor are low sexual desire and erectile dysfunction. Other symptoms include:
- Decrease in muscle mass and strength
- Decrease in bone mineral density
- Weight gain
- Increase in cholesterol levels
- Enlargement of breasts or gynecomastia
- Difficulty concentrating
Older men experiencing any of these symptoms should get their testosterone levels checked, specifically free testosterone levels.
One important component in raising testosterone levels is reducing body fat percentage. Normally, some of the testosterone men have is converted to estrogen, which maintains bone strength by preventing bone resorption. However, the conversion happens within fat cells, and because obese men have more fat cells, more testosterone becomes estrogen.
For this reason, obese men are highly encouraged to lose weight. In a study presented at the Endocrine Society’s annual meeting in 2012, a group of 293 overweight and prediabetic men men aged between 45 and 65 exercised for at least 150 minutes each week, ate fewer calories and fat for a year.
At the end of the study period, only 11% of the participants still had low testosterone level while most men demonstrated an increase of about 15%.
Fat is in fact one of the critical players involved in testosterone production and metabolism, and along with carbs, is now recognized in fitness circles as the boss when it comes to boosting testosterone levels.
This has been proven in this study which found that diets consisting of 40% monounsaturated and saturated fats were associated with an increase in testosterone levels. On the other hand, diets with 20% fat decreased testosterone levels.
Interestingly, the study also found that replacing a high-protein, low-carbohydrate diet caused a corresponding decrease in testosterone levels.
In another study, switching from a high-fat diet to a low-fat, high-fiber diet resulted in a 12% decrease in circulating testosterone levels.
As a general rule, experts recommend getting 45% of calories from carbohydrates (low-fiber and low-gluten carbs from potatoes, rice, fruit and sugar), 35% from fat (polyunsaturated and monounsaturated fats from olive oil, avocados, nuts, organic dairy, and coconut oil), and 20% from protein from animal sources.
More popularly known as the ‘sunshine vitamin’, vitamin D isn’t actually a vitamin; it’s a steroid hormone that regulates more than 1,000 metabolic processes and physiological functions, including hormone production, fertility, antibody production, immune function and calcium metabolism.
Almost every organ in the body has vitamin D receptors. The blood vessels, heart muscles, the skin and the airways all have vitamin D receptors and use vitamin D in one way or another. The testicles, too, have tons of them, which suggests that vitamin D has a pretty important role in testosterone production. In fact, mice that don’t have vitamin D receptors in the testicles have abnormally low testosterone.
One human study found that men with sufficient vitamin D levels had significantly more serum testosterone and lower testosterone-binding protein than men who had low vitamin D. A study involving older men found that those who take vitamin D supplements have higher testosterone levels than men who don’t.
The chart below clearly shows the spike in serum testosterone levels that occurred as serum vitamin D levels rose. However, testosterone levels plateau as soon as vitamin D levels hit 80 nmol per liter.
This last study found that supplementing with 3332 IU’s of vitamin daily for a year increased testosterone levels by 25.2%
The best way to get vitamin D is through direct sun exposure for at least 10 minutes daily. Exposing bare chest to sunlight actually works 120% better, but exposing the genitals increases testosterone levels by 200%.
Intermittent fasting (IF) is a dietary pattern that involves purposely skipping meals with the end-goal of improving body composition.
IF has been suggested to significantly burn fat and reduce body mass. It’s also been shown to improve heart disease and metabolic diseases like type 2 diabetes by improving insulin sensitivity and reducing body fat.
Not only can IF improve overall health, clinical trials have shown that it can improve testosterone levels as well.
In a study by Rojdmark, short term fasting increased testosterone levels in non-obese men by an eye-popping 180%!
Another study reported that IF over a period of 24 hours resulted in a massive increase in growth hormone levels of 1300% in women and 2000% in men. Although the study measured only growth hormone levels, it’s been proven that growth hormone actually have a direct stimulatory effect on the testicles to produce more testosterone.
Chronic stress is testosterone’s natural enemy. It brings with it a rise in cortisol, which is the bad guy responsible for many of the chronic disease we see today. Being a catabolic hormone, which means it destroys everything unfortunate enough to be in its path, cortisol not only eats at your muscle and causes widespread oxidative damage and inflammation- it also destroys testosterone molecules inside the testicles and in the blood stream.