Such sort of injuries varies in severity and extent of damage markedly from one person to the other and withdrawal of the drug/supplement coupled with proper medical attention suffice in terms of alleviating the symptoms.[8,12] This was observed in the present case. However, the liver injury observed here may not be confidently linked to product consumption as the subject later reported that the following recovery he consumed two more courses of the booster with no side effects. Tests performed following hospital discharge, and repeated use of the product showed AST and ALT to be slightly high, whereas the rest of the blood parameters tested appeared to be normal. The AST/ALT ratio is considered to be a very important parameter for the evaluation of liver diseases, such as non-alcoholic fatty liver disease,[13] though it is rarely considered alone. Overall, the evidence was inconclusive in the present work in terms of linking the use of a testosterone booster with liver injury. However, even though a single case report cannot establish causality with statistical power.[13] Further research on the usage of a commercial testosterone booster within large populations for a long period is necessary to investigate whether the symptoms shown in the present case were significantly present in other athletes consuming the same commercial product or not. To guarantee an optimal outcome with no severe side effects, further research is warranted to confirm the present findings and determine whether the effects observed in this case report would be statistically significant in larger samples.
Researchers at Ball State University found that “strength training can induce growth hormone and testosterone release.” (6) Another study from the University of Nebraska Medical Center researched the acute effects of weight lifting on serum testosterone levels. (7) The results concluded that even moderate weight lifting and light weightlifting increased serum testosterone levels in participants.
Testosterone retains nitrogen and is an essential ingredient in the development and maintenance of muscle mass (Sinha-Hikim et al 2006). With a diminution in testosterone, muscle mass diminishes as does strength. Weakness and fatigue result. A number of studies have demonstrated the ability of testosterone to restore lean body mass (muscle) in hypogonadal men, while at the same time causing a reduction in fat mass (Wang et al 2004). Treatment of hypogonadal men with testosterone results in improvement in overall physical performance as well as strength as assessed by, eg, hand grip power (Page 2005). Because of decreased muscle strength and impaired balance, older hypogonadal men are susceptible to falling and since they may already be osteopenic or osteoporotic as a consequence of hypogonadism, they are at increased risk for fracture as a result of the fall (Szulc et al 2003). Men with low levels of testosterone as in androgen deprivation therapy for prostate cancer, have a significant decrease in lean body mass and hemoglobin, while at the same time they experience an increase in weight, body fat and body mass index (Smith et al 2002). Treatment of frail hypogonadal men with testosterone, therefore, can result in changes in muscle gene expression, increased muscle mass, improvements in strength, power and endurance and improved physical function.
Japanese Knotweed (a.k.a Hu Zhang or Polygonum cuspidatum) is highlighted by WebMD as needing more evidence to rate its effectiveness in a number of different areas: like treating constipation and liver or heart disease. They also warn that it can interact poorly with medications that are changed and broken down by the liver, and those that slow blood clotting (anticoagulants and antiplatelets).
Acne and Allergic Reactions: The testosterone is universally regarded as one of the triggering factors for acne. It stimulates the activity of oil glands making the skin more oily and vulnerable to acne. This body hormone might also cause allergic reactions, such as hives, rash, difficulty breathing, itching, chest tightness, and big swelling of the facial parts.
The ingredients in testosterone supplements may be different. Some testosterone supplements contain zinc and magnesium. They increase testosterone levels in men who exercise. Some other testosterone supplements have hormones like DHEA (dehydroepiandrosterone) and pregnenolone. They help with making new testosterone and may help improve the ability to have an erection. But it doesn't seem to be helpful if the problem with erections is caused by diabetes or nerve disorders. Some testosterone booster supplements contain natural ingredients like herbs and botanicals. They may increase testosterone by increasing a hormone produced by the brain, which signals the testicles to produce more testosterone. In addition, others work by releasing bound testosterone, so it is in a form the body can use. Studies do not provide strong evidence that women benefit from taking these supplements. You need to talk to your doctor or pharmacist before starting a testosterone booster supplement. Discuss your medical history and current prescribed medications, over the counter medications, and any supplements that you are taking. Your doctor or pharmacist can tell you if a testosterone booster supplement is right for you. Once you know if a testosterone booster supplement is right for you, Walgreens has a variety of testosterone booster supplements to choose from and they come in different forms like tablets, capsules or gels.

Some of the effects of testosterone treatment are well recognised and it seems clear that testosterone treatment for aging hypogonadal men can be expected to increase lean body mass, decrease visceral fat mass, increase bone mineral density and decrease total cholesterol. Beneficial effects have been seen in many trials on other parameters such as glycemic control in diabetes, erectile dysfunction, cardiovascular risk factors, angina, mood and cognition. These potentially important effects require confirmation in larger clinical trials. Indeed, it is apparent that longer duration randomized controlled trials of testosterone treatment in large numbers of men are needed to confirm the effects of testosterone on many aspects of aging male health including cardiovascular health, psychiatric health, prostate cancer and functional capacity. In the absence of such studies, it is necessary to balance risk and benefit on the best available data. At the present time the data supports the treatment of hypogonadal men with testosterone to normalize testosterone levels and improve symptoms. Most men with hypogonadism do not have a contraindication to treatment, but it is important to monitor for adverse consequences including prostate complications and polycythemia.
Mental status changes including excess aggression are a well known phenomenon in the context of anabolic steroid abuse (Perry et al 1990). An increase in self-reported aggressive behaviors have also been reported in one double blind placebo controlled trial of testosterone in young hypogonadal men (Finkelstein et al 1997), but this has not been confirmed in other studies (Skakkebaek et al 1981; O’Connor et al 2002). Aggression should therefore be monitored but in our experience is rarely a significant problem during testosterone replacement producing physiological levels.
Testosterone is an anabolic steroid hormone that plays a critical role in metabolism, sex drive, muscle building, mood regulation, memory & cognitive function.  Normal testosterone levels play a huge role in maintaining optimal weight as well as reducing risk of degenerative diseases such as osteoporosis, heart disease, diabetes, & certain cancers (1, 2, 3).
Cross-sectional studies have found a positive association between serum testosterone and some measures of cognitive ability in men (Barrett-Connor, Goodman-Gruen et al 1999; Yaffe et al 2002). Longitudinal studies have found that free testosterone levels correlate positively with future cognitive abilities and reduced rate of cognitive decline (Moffat et al 2002) and that, compared with controls, testosterone levels are reduced in men with Alzheimer’s disease at least 10 years prior to diagnosis (Moffat et al 2004). Studies of the effects of induced androgen deficiency in patients with prostate cancer have shown that profoundly lowering testosterone leads to worsening cognitive functions (Almeida et al 2004; Salminen et al 2004) and increased levels of serum amyloid (Gandy et al 2001; Almeida et al 2004), which is central to the pathogenesis of Alzheimer’s disease (Parihar and Hemnani 2004). Furthermore, testosterone reduces amyloid-induced hippocampal neurotoxity in vitro (Pike 2001) as well as exhibiting other neuroprotective effects (Pouliot et al 1996). The epidemiological and experimental data propose a potential role of testosterone in protecting cognitive function and preventing Alzheimer’s disease.
This is because your body is really good at self-regulating your hormone levels. So if you have normal testosterone levels, boosting above your natural base level may at best give you a few hours while your body makes, and then immediately processes out, the excess testosterone. This means you might experience higher than your average testosterone levels, but not by much, and only for a little while.
Bhatia et al (2006) studied 70 male patients with type2 diabetes mellitus (age range 24–78 years). Thirty-seven subjects were found to have hypogonadism based on a calculated free testosterone level of less than 6.5 μg/dl. The hypogonadal group had a statistically significant lower hematocrit. Anemia was observed in 23% of the patients (16 out of 70). In 14 of 15 anemic patients calculated free testosterone was low.
Ashwagandha is sometimes included in testosterone supplements because of the hypothesis that it improves fertility. However, we couldn’t find sufficient evidence to support this claim (at best, one study found that ashwagandha might improve cardiorespiratory endurance). WebMD advocates caution when taking this herb, as it may interact with immunosuppressants, sedative medications, and thyroid hormone medications.

That there is an association between depression and testosterone concentration seems possible because of the observation that depression may be associated with reduced testosterone concentrations, hypogonadal men may have their symptoms of depression relieved by TRT and that testosterone itself may have anti-depressant properties (Pope et al 2003). The evidence, however, is inconsistent. Seidman and colleagues (2002), for example, found that there was no relationship between testosterone and depression but there was an association of testosterone with dysthymia. McIntyre and colleagues (2006), on the other hand, found that middle-aged men with depression did have a reduction in bio-available testosterone.

Here’s one proof: in a number of British rivers, 50 percent of male fish were found to produce eggs in their testes. According to EurekAlert,3 EDCs have been entering rivers and other waterways through sewage systems for years, altering the biology of male fish. It was also found that fish species affected by EDCs had 76 percent reduction in their reproductive function.
4. Foods rich in vitamin A. Vitamin A is more commonly known for its association with eyesight improvement, but it is also a vitamin supplements the production of testosterone. The June 2004 issue of the Clinical Endocrinology journal published research conducted by Israel’s Kaplan Medical Center. This study involved Israeli boys that had delays in puberty. These boys were given Vitamin A supplements and foods rich in Vitamin A over the course of 6 months, and most of them showed an improvement with their testosterone levels. If you want to boost the level of testosterone in your body, food types that are rich in Vitamin A are carrots, sweet potatoes, squash, cantaloupe and eggs.
When you’re under stress (be it from lack of sleep, workplace stress, emotional stress, stress from a bad diet, overtraining etc.), your body releases cortisol. Cortisol blunts the effects of testosterone (47), which makes sense from an evolutionary point of view – if we were stressed as cavemen chances are it was a life or death situation – not running late to a meeting - in this state (i.e. running from a lion) the body wouldn’t care if you couldn’t get it up, there was more to worry about!
The testosterone supplements are primarily used to enhance the body muscle mass. Various studies have shown that testosterone therapy is also crucial in development of the memory as well as concentration, increase the level of energy, and increase libido or sexual desire. However, use of high levels of testosterone booster can also contribute to the development of certain medical conditions and health problems. Two types are available on the market, legal boosters, and illegal boosters. There are also certain excellent natural testosterone boosters that are efficient and so not have side effects.
Testosterone is an essential hormone for men, and a decline in the levels can occur due to many reasons, but these natural supplements are great. They are safe to use and don’t have any side effects, that’s why you can take these supplements without doctor consultations. But if you have any other health issues, then consult a doctor before taking them.
It seems like today it’s a badge of honor to train every day until exhaustion. The ethos is to push yourself harder and harder every day. If that’s your philosophy towards exercise, you might be sabotaging your testosterone levels (as well as your 20 Mile March). Studies have shown that overtraining can reduce testosterone levels significantly. Yes, it’s important to exercise hard, but it’s even more important to give your body rest so it can recuperate from the damage you inflicted upon it.

I was reading in the university health news daily website that a study performed by researchers at the University of Texas M.D. Anderson Cancer Center found that men with prostate cancer who ate 3 tablespoons of milled or ground flax seeds each day had decreased prostate cancer cell proliferation compared to similar men who did not eat flax seeds. According to the American Cancer Society, men who supplement their diets with flax seed have lower PSA levels and slower growth of benign as well as cancerous prostate cells.
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).

Acne and Allergic Reactions: The testosterone is universally regarded as one of the triggering factors for acne. It stimulates the activity of oil glands making the skin more oily and vulnerable to acne. This body hormone might also cause allergic reactions, such as hives, rash, difficulty breathing, itching, chest tightness, and big swelling of the facial parts.
4. Foods rich in vitamin A. Vitamin A is more commonly known for its association with eyesight improvement, but it is also a vitamin supplements the production of testosterone. The June 2004 issue of the Clinical Endocrinology journal published research conducted by Israel’s Kaplan Medical Center. This study involved Israeli boys that had delays in puberty. These boys were given Vitamin A supplements and foods rich in Vitamin A over the course of 6 months, and most of them showed an improvement with their testosterone levels. If you want to boost the level of testosterone in your body, food types that are rich in Vitamin A are carrots, sweet potatoes, squash, cantaloupe and eggs.
Having low T is associated with decreased sex drive and less muscle mass, and one new study even found that lower levels of testosterone may raise the risk of depression. Fortunately, strength training spikes T, and living a healthy lifestyle also goes a long way toward keeping your levels topped off. But there are some completely natural compounds that can help as well.
Longjack, also known as Tongkat ali and pasak bumi, is a shrub hailing from Southeast Asia purporting to improve libido. It’s gaining traction in the scientific community for potentially increasing testosterone levels, and researchers at South Africa’s University of the Western Cape found that longjack improved testosterone levels and muscular strength in physically active seniors (a population with typically low testosterone).

Christopher Walker is a co-founder of UMZU and creator of the Thermo Diet. He is the first person to get a Duke Neuroscience degree in 3 years. After naturally solving his own health complications with a brain tumor as a teenager, he has devoted his life to creating all-natural products and education to help men, women, children and pets to improve their own health naturally using science-backed research.
The second theory is similar and is known as "evolutionary neuroandrogenic (ENA) theory of male aggression".[78][79] Testosterone and other androgens have evolved to masculinize a brain in order to be competitive even to the point of risking harm to the person and others. By doing so, individuals with masculinized brains as a result of pre-natal and adult life testosterone and androgens enhance their resource acquiring abilities in order to survive, attract and copulate with mates as much as possible.[78] The masculinization of the brain is not just mediated by testosterone levels at the adult stage, but also testosterone exposure in the womb as a fetus. Higher pre-natal testosterone indicated by a low digit ratio as well as adult testosterone levels increased risk of fouls or aggression among male players in a soccer game.[80] Studies have also found higher pre-natal testosterone or lower digit ratio to be correlated with higher aggression in males.[81][82][83][84][85]
4. Foods rich in vitamin A. Vitamin A is more commonly known for its association with eyesight improvement, but it is also a vitamin supplements the production of testosterone. The June 2004 issue of the Clinical Endocrinology journal published research conducted by Israel’s Kaplan Medical Center. This study involved Israeli boys that had delays in puberty. These boys were given Vitamin A supplements and foods rich in Vitamin A over the course of 6 months, and most of them showed an improvement with their testosterone levels. If you want to boost the level of testosterone in your body, food types that are rich in Vitamin A are carrots, sweet potatoes, squash, cantaloupe and eggs.
Testosterone is only one of many factors that influence aggression and the effects of previous experience and environmental stimuli have been found to correlate more strongly. A few studies indicate that the testosterone derivative estradiol (one form of estrogen) might play an important role in male aggression.[66][67][68][69] Studies have also found that testosterone facilitates aggression by modulating vasopressin receptors in the hypothalamus.[70]
There are valid concerns about the safety of long-term treatment with testosterone particularly with respect to the cardiovascular system and the potential for stimulating prostate cancer development. There are no convincing hard data, however, to support these concerns. If anything, the data strongly suggest that adequate testosterone availability is cardioprotective and coronary risk factors such as diabetes, obesity and the metabolic syndrome are associated with reduced testosterone levels. It is certainly appropriate to avoid giving testosterone to men with prostate or breast cancer but it is not appropriate to accuse testosterone of inducing the development of de novo prostate cancers since evidence for this accusation is lacking (Wang et al 2004; Feneley and Carruthers 2006).
If you’re a frequent reader here in AM, you already know that increased dietary fat intake is directly correlated with increased testosterone production. And not only that, but the types of fat that increase T seem to be saturated fats (SFAs) and monounsaturated fats (MUFAs), while polyunsaturated (PUFAs) actually tend to lower testosterone (more here).
ZMA (unnecessary). So when I researched how to increase testosterone, a supplement called ZMA kept popping up. It’s a blend of zinc, magnesium, and vitamin B6. The purported benefits of ZMA include better and deeper sleep which indirectly is supposed to increase testosterone. Zinc and magnesium are necessary minerals in testosterone production, so a mega-dose should be useful, right? Well, no. I bought some and took it during the duration of experiment. I should have done some more research before I made the purchase. While one study in 1998 showed increased strength among athletes taking ZMA, two recent studies (study 1, study 2) have shown that it has absolutely no effect on total or free testosterone levels. Crap. My advice, unless you have a zinc and magnesium deficiency, no need to waste your money on this.
Mental status changes including excess aggression are a well known phenomenon in the context of anabolic steroid abuse (Perry et al 1990). An increase in self-reported aggressive behaviors have also been reported in one double blind placebo controlled trial of testosterone in young hypogonadal men (Finkelstein et al 1997), but this has not been confirmed in other studies (Skakkebaek et al 1981; O’Connor et al 2002). Aggression should therefore be monitored but in our experience is rarely a significant problem during testosterone replacement producing physiological levels.
14. Volek JS, Volk BM, Gómez AL, Kunces LJ, Kupchak BR, Freidenreich DJ, Aristizabal JC, Saenz C, Dunn-Lewis C, Ballard KD, Quann EE, Kawiecki DL, Flanagan SD, Comstock BA, Fragala MS, Earp JE, Fernandez ML, Bruno RS, Ptolemy AS, Kellogg MD, Maresh CM, Kraemer WJ. Whey protein supplementation during resistance training augments lean body mass. J Am Coll Nutr. 2013;32(2):122-35. PMID: 24015719

“I'm a truck driver and for 13 hours a night I sit in my truck and I drive. Out of boredom, I'd stop and eat. That was all until Andro400 – ever since then my life has changed. I started out weighing 341 pounds, and since taking Andro400 I've dropped 85 pounds! There's no cravings – I actually don't even think about food anymore. One thing that Andro400 said on the radio ad is it attacks belly fat – well let me tell you it did – the 2nd month is where I saw a drastic change in the size of my stomach. I've lost 6 inches! I'm sleeping better. My knee pain went away. I've had some lower back issues and that went away, and I can only attribute that to Andro400. It's a Life Changer for me!”
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Testogenix is quickly becoming one of the best-selling testosterone supplements on the market! Its 12 clinically-proven ingredients have helped men everywhere dramatically raise their testosterone levels and do it safely with a 100% All-Natural Ingredients. Priced under $40, it is no wonder why Testogenix has become our User’s Favorite Testosterone Supplement. When surveyed, Testogenix was chosen as their top choice for its affordable, safe & effective formulation all for UNDER $40!
Everyone knows that carbohydrates are extremely important for testosterone production, but instead of reaching for grains during your next meal, stack your plate high with potatoes. Research reveals that grains have inflammatory properties, but the testosterone-friendly starches in potatoes will have the bodybuilder in your life smiling at dinnertime!
One study found that men who took 3,332 international units (IU) of vitamin D daily for one year significantly increased their testosterone levels. But vitamin D supplements may only work for men who are severely deficient in this specific vitamin. Another study found that men without a vitamin D deficiency had no increase in testosterone levels after taking vitamin D.
The effects of testosterone in humans and other vertebrates occur by way of multiple mechanisms: by activation of the androgen receptor (directly or as DHT), and by conversion to estradiol and activation of certain estrogen receptors.[109][110] Androgens such as testosterone have also been found to bind to and activate membrane androgen receptors.[111][112][113]
Nutritional developers formulated Nugenix® with Testofen®, a key natural ingredient to help boost “free” testosterone along with resistance training. This key ingredient is carefully extracted from the fenugreek plant. A Testofen® study in Irvine, California indicated positive free testosterone-related results. Nugenix also includes L-Citrulline Malate, Tribulus, Zinc, plus Vitamins B6 and B12 to help promote overall health and performance.*
To get a good dietary source of selenium, you can eat shellfish or Brazilian nuts. 1-2 Brazilian nuts is enough to get 200% of your daily intake. You don’t need any more than that. Read more about increasing testosterone with Brazilian nuts here. It’s a good idea to get your selenium levels checked before hand and then adjust your diet as needed to avoid selenium toxicity.
If you're a man who's experiencing symptoms such as decreased sex drive, erectile dysfunction, depressed mood, and difficulties with concentration and memory, and you think low testosterone may be to blame, you can have your levels tested. Since testosterone levels fluctuate throughout the day, you'll probably need more than a blood test to get a true picture of your levels.
Testosterone functions within the brain. There are several lines of evidence for this: there are androgen receptors within the brain; testosterone is converted to both dihydrotestosterone (DHT) and estradiol by the actions of 5-α-reductase and aromatase respectively in the brain; steroid hormones promote neuronal cell growth and survival (Azad et al 2003). Testosterone enhances cerebral perfusion in hypogonadal men and that perfusion takes place specifically in Brodman areas 8 and 24, regions of the brain that are concerned with: strategic planning, higher motor action, cognitive behaviors, emotional behavior, generalized emotional reaction, wakefulness and memory (Greenlee 2000; Azad et al 2003). Studies of cognition demonstrate that older men with higher levels of free testosterone index (a surrogate measure of bioavailable testosterone) have better scores in tests of: visual memory, verbal memory, visuospatial functions and visuomotor scanning. Hypogonadal men have lower scores in tests of memory, visuospatial function, with a faster decline in visual memory (Moffat et al 2002). In a very small, short term placebo-controlled study hypogonadal men with Alzheimer’s Disease (AD) treated with testosterone demonstrated a modest improvement in a cognition assessment score in AD (Tan and Pu 2003).
No one will argue with the well-established fact that the dramatic lows of testosterone as seen in castration or other significant primary testicular disturbances such as those induced by chemotherapy, radiation therapy, congenital problems, or as seen in secondary testicular insufficiency (eg, large compressive pituitary or hypothalamic tumors) produce dramatic signs and symptoms of testosterone deficiency that require testosterone replacement therapy. Less clear, or at least more controversial, is the necessity of treating the gentler reduction of testosterone seen in the aging process.
Here’s a scary thought: You may be less of a man than your father was—at least hormonally. A study in the Journal of Clinical Endocrinology and Metabolism found that, on average, testosterone levels were higher in men of the same age in the ’80s than they were in the 2000s (due, researchers speculate, to higher rates of obesity and the wider use of medication these days).  
Boron, a mineral, keeps the cell walls of plants strong. Eating dried fruits and nuts gives you abundant amounts of boron. You can also take boron supplements. It's important to keep your daily boron intake at less than 20 mg, however, according to a current factsheet available from the U.S. National Library of Medicine. High doses of boron can cause serious side effects such as skin inflammation and peeling, irritability, tremors or depression.
   The International Journal of Sports Physiology and Performance recently studied tennis players, rugby teams, and wrestlers to find a link between testosterone and competitive outcome. They found that the difference between winning and losing was reflected in testosterone levels! The athletes' own natural testosterone prior to the game was directly related to the outcome after the game -- the higher the testosterone, the more frequently the athlete won.6
The amount of testosterone synthesized is regulated by the hypothalamic–pituitary–testicular axis (see figure to the right).[129] When testosterone levels are low, gonadotropin-releasing hormone (GnRH) is released by the hypothalamus, which in turn stimulates the pituitary gland to release FSH and LH. These latter two hormones stimulate the testis to synthesize testosterone. Finally, increasing levels of testosterone through a negative feedback loop act on the hypothalamus and pituitary to inhibit the release of GnRH and FSH/LH, respectively.
That there is an association between depression and testosterone concentration seems possible because of the observation that depression may be associated with reduced testosterone concentrations, hypogonadal men may have their symptoms of depression relieved by TRT and that testosterone itself may have anti-depressant properties (Pope et al 2003). The evidence, however, is inconsistent. Seidman and colleagues (2002), for example, found that there was no relationship between testosterone and depression but there was an association of testosterone with dysthymia. McIntyre and colleagues (2006), on the other hand, found that middle-aged men with depression did have a reduction in bio-available testosterone.
The changes in average serum testosterone levels with aging mean that the proportion of men fulfilling a biochemically defined diagnosis of hypogonadism increases with aging. Twenty percent of men aged over 60 have total testosterone levels below the normal range and the figure rises to 50% in those aged over 80. The figures concerning free testosterone are even higher as would be expected in view of the concurrent decrease in SHBG levels (Harman et al 2001).

In summary it’s important to know that this topic is still hotly debated, and there are a lot of inconsistencies in the data. We do know that soy contains phytoestrogens and does seem to have a lot of affects on the body, including some studies that show decreased Testosterone levels. For that reason (and the fact that it tastes like ass) I avoid it, and I recommend you also avoid it (in particular soy isolates!) if you’re seeking higher testosterone.

^ Mehta PH, Jones AC, Josephs RA (Jun 2008). "The social endocrinology of dominance: basal testosterone predicts cortisol changes and behavior following victory and defeat" (PDF). Journal of Personality and Social Psychology. 94 (6): 1078–93. CiteSeerX 10.1.1.336.2502. doi:10.1037/0022-3514.94.6.1078. PMID 18505319. Archived from the original (PDF) on April 19, 2009.
The researchers found that the dose of testosterone required to produce different effects in the body varied widely. The influence of testosterone and estradiol also differed. As the testosterone gel dose was reduced, the scientists showed, reductions in lean mass, muscle size, and leg-press strength resulted from decreases in testosterone itself. In contrast, increases in body fat were due to the related declines in estradiol. Both testosterone and estradiol levels were associated with libido and erectile function.
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