While testosterone stimulates a man’s sex drive, it also aids in achieving and maintaining an erection. Testosterone alone doesn’t cause an erection, but it stimulates receptors in the brain to produce nitric oxide. Nitric oxide is a molecule that helps trigger a series of chemical reactions necessary for an erection to occur. When testosterone levels are too low, a man may have difficulty achieving an erection prior to sex or having spontaneous erections (for example, during sleep).


These results have been echoed in clinical trials. A meta-analysis of 24 RCTs looked at weight loss caused by diet or bariatric surgery:[22] In the diet studies, the average 9.8% weight loss was linked to a testosterone increase of 2.9 nmol/L (84 ng/dL). In the bariatric-surgery studies, the average 32% weight loss was linked to a testosterone increase of 8.7 nmol/L (251 ng/dL).
The final two studies looked directly at soy vs testosterone levels. The first looked at introducing consumption of soya flour on testosterone levels. They found that those who ate the Soy flour lowered their T levels during the study (43). And the second study looked at the consumption of soy protein isolates (powder) in healthy men. They found that testosterone levels decreased upon consumption of soy powder (45).
We should probably start with the elephant in the room: do these supplements increase testosterone? The answer is probably yes. There are some ingredients that help convince your body to produce more testosterone, but there’s a catch. Testosterone boosters aren’t actually great at boosting; that is, at pushing your testosterone levels above your healthy, normal balance. Boosters typically act more like restorers — helping bring low testosterone levels back to that healthy equilibrium rather than boosting you above normal testosterone levels. Just like how if you have anemia, taking a vitamin B12 supplement can help restore your energy and reduce fatigue, but if your B12 levels are good, a supplement won’t give you super energy levels to stay awake for three days — your body will likely just process (read: pee) out the extra.
In fact, high cortisol deals a crushing blow to testosterone in two ways. During, long-lasting stress, high amounts of cortisol release very often and have a direct negative influence on T levels. Thus, cortisol inhibits testosterone synthesis in the testes and hypothalamus. In addition, the production of cortisol is impossible without cholesterol. But testosterone synthesis also demands cholesterol. Since during stress cholesterol is first of all used for making cortisol, T levels simply plummet.
Does the diminution that age brings with it in both total and bioavailable T have any clinical significance? This question leads us to the theme of this paper, “The Many Faces of Testosterone”. If testosterone were simply a “sex hormone” involved only with sexual desire and arousal we might tend to dismiss testosterone treatment in the aging man as merely a “life-style” therapy without any substantive basis for broad physiological necessity. The fact is, however, that the sexual attributes of testosterone are the least of its physiological necessities and that testosterone has a broad spectrum of demonstrated physiological functions as well as a wide variety of physiological and pathophysiological associations about which we are just learning.
If in a 46 XY individual testosterone is either not produced in adequate concentrations as in gonadal dysgenesis (MacLaughlin and Donahue 2004), or in the absence of the enzyme 17 alpha-hydroxylase so that testosterone is not produced (Ergun-Longmire et al 2006), or testosterone androgen receptors are absent as in the androgen insensitivity syndrome (Hughes and Deeb 2006), phenotypic females will result.
It is hard to know how many men among us have TD, although data suggest that overall about 2.1% (about 2 men in every 100) may have TD. As few as 1% of younger men may have TD, while as many as 50% of men over 80 years old may have TD. People who study the condition often use different cut-off points for the numbers, so you may hear different numbers being stated.

Beast Sports recommends taking four capsules twice per day. The pills are about the same size as a multivitamin or a Tylenol liquid gel pill — not tiny tablets, unfortunately, but they aren’t horse pills. They smell like the boxes of raisins your Mom packed into your school lunch, but stale, like they were forgotten in the pantry for a few years, and a little spicy, like she sprinkled curry powder on them. If you follow this eight pills per day regime, your $46 bottle will last you twenty-two days, and cost you about $2 per day.


Watch out for ingredients that interfere with blood clotting If you are taking any kind of blood medication, take aspirin or ibuprofen, or have any kind of blood-related condition, you’ll want to consult your doctor before taking any of these supplements. Fenugreek, Forskolin, and Acetyl-L-carnitine are just a few of the ingredients that can make these situations worse and increase your chances of bruising and bleeding.
Steven Doerr, MD, is a U.S. board-certified Emergency Medicine Physician. Dr. Doerr received his undergraduate degree in Spanish from the University of Colorado at Boulder. He graduated with his Medical Degree from the University Of Colorado Health Sciences Center in Denver, Colorado in 1998 and completed his residency training in Emergency Medicine from Denver Health Medical Center in Denver, Colorado in 2002, where he also served as Chief Resident.
Both Beast Sports’ Super Test and iSatori’s ISA-Test contain a proprietary blend, which means they don’t disclose the amount of each and every ingredient in the mix. This is only a problem if there is an ingredient tucked into a proprietary blend for which we need to know an amount, like magnesium and zinc. While none of the ingredients in Beast Sports’s proprietary blend raised any red flags, iSatori’s blend contains melatonin, a hormone that helps regulate sleep. Melatonin is an ingredient that has a hard upper limit — Healthline suggests at most 10mg for an adult — and even lower doses can interact poorly with many medications. Since we can’t confirm whether the amount of melatonin in iSatori’s proprietary blend is under 10mg, we cut iSatori.
When females have a higher baseline level of testosterone, they have higher increases in sexual arousal levels but smaller increases in testosterone, indicating a ceiling effect on testosterone levels in females. Sexual thoughts also change the level of testosterone but not level of cortisol in the female body, and hormonal contraceptives may affect the variation in testosterone response to sexual thoughts.[51]
Dr. Anthony’s Notes: DHEA is a powerful supplement for testosterone, energy, and overall well-being in our older Fit Fathers. A small dose of 25-50mg/day is enough to exert noticeable benefits. This supplement is over-the-counter. Verdict: this is one of the testosterone supplements that work. How To Take DHEA: Take 25-50mg once per day with food. Special Medical Note: DHEA is a MILD CYP3A4 inhibitor (a liver enzyme that processes MANY very common medications). This is the same isoenzyme that Grapefruit inhibits – albeit DHEA inhibits to a much weaker degree. If you’ve ever heard “don’t eat grapefruit with your Lipitor (cholesterol medication)”… this is the reason why. When we inhibit the CYP3A4 enzyme, more of the medications you're taking circulates (it’s not metabolized as fast). Check with your doctor for medication interactions before using DHEA.
TT may help you but it may have adverse (harmful) results. (See discussion of these side effects below.) The Federal Drug Administration (FDA) has said that testosterone drug labels should state that there is a risk for heart disease and stroke for some men using testosterone products. All men should be checked for heart disease and stroke before, and periodically while on, TT. The AUA however, on careful review of evidence-based peer review literature, has stated that there is no strong evidence that TT either increases or decreases the risk of cardiovascular events.
A 2010 study published in the journal Hormones and Behavior first suggested this when researchers evaluated the “dual-hormone hypothesis” clinically. (11) They discovered that when cortisol is elevated, testosterone responds by elevating as well but soon after bottoms out at a much lower level than before cortisol kicked in! That means you want to find ways to relieve stress to keep your testosterone levels up.
Intracoronary artery infusion of testosterone causes significant coronary artery dilatation and not constriction as previously thought (Webb et al 1999). When degree of coronary obstruction is assessed by angiography, there is a direct relationship between degree of coronary artery narrowing and reduced testosterone levels (Phillips et al 1994). Men with low testosterone levels have been observed to have: premature atherosclerosis, increased visceral adipose tissue, hyperinsulinemia, and other risk factors for myocardial infarction (Phillips 2005). Insulin resistance has been shown to be associated with a decrease in Leydig cell secretion of testosterone (Pitteloud et al 2005). Muller and colleagues suggest that low endogenous total testosterone and SHBG levels increase the risk of metabolic syndrome in aging and aged men. They demonstrated that low levels of testosterone are related to lower insulin sensitivity and higher fasting insulin levels (Muller et al 2005). These authors speculate that testosterone might play a protective role in the development of metabolic syndrome, insulin resistance, diabetes mellitus and cardiovascular disease in aging men.
The first of the natural testosterone boosters is intermittent fasting. One of the biggest intermittent fasting benefits? It’s been shown to increase testosterone by nearly 200 percent or even up to 400 percent. (4) In addition, a study by the University of Virginia Medical School noted that growth hormone levels increased 2,000 percent over the baseline in men who ate no calories for 24 hours, and growth hormone levels are correlated with testosterone. (5)

TT may help you but it may have adverse (harmful) results. (See discussion of these side effects below.) The Federal Drug Administration (FDA) has said that testosterone drug labels should state that there is a risk for heart disease and stroke for some men using testosterone products. All men should be checked for heart disease and stroke before, and periodically while on, TT. The AUA however, on careful review of evidence-based peer review literature, has stated that there is no strong evidence that TT either increases or decreases the risk of cardiovascular events.
When females have a higher baseline level of testosterone, they have higher increases in sexual arousal levels but smaller increases in testosterone, indicating a ceiling effect on testosterone levels in females. Sexual thoughts also change the level of testosterone but not level of cortisol in the female body, and hormonal contraceptives may affect the variation in testosterone response to sexual thoughts.[51]
The most common "out of balance" testosterone levels are found to be on the low side of normal; this occurs because a male's highest testosterone level usually peaks at about age 20, and then it decreases slowly with age. It has been suggested that a 1% decrease in testosterone level per year is not unusual for middle-aged (30 to 50 years old) and older males. While this decrease may not be noticeable in some men, others may experience significant changes starting in their middle-aged years or more commonly at age 60 and above. This drop in testosterone levels is sometimes termed hypogonadism, "male menopause" or andropause.
As blood levels of testosterone increase, this feeds back to suppress the production of gonadotrophin-releasing hormone from the hypothalamus which, in turn, suppresses production of luteinising hormone by the pituitary gland. Levels of testosterone begin to fall as a result, so negative feedback decreases and the hypothalamus resumes secretion of gonadotrophin-releasing hormone. 
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