Welcome to the first installment of Testosterone Week! Based on the reaction from yesterday’s announcement post , this is a subject that many of you are both interested in and passionate about. I’m looking forward to reading your constructive contributions to the discussion.
I know many of you are clamoring for the “how-to” part of this series (which will go up on Thursday), but before we get to that, it’s important to cover why you should even care about your testosterone levels in the first place, what T is and how it’s made, and how to get properly tested for it. Building a sound foundation before we dive into the nitty gritty details will be highly beneficial.
Today we take a look at some of the physical and psychological benefits that come with having optimal testosterone levels (I’ll talk about what “optimal” means regarding T later this week). You probably know about some of the benefits already, but some of the ones I discuss may surprise you. When appropriate, I’ll report any health benefits that I experienced during my own 90-day testosterone boosting experiment.
First, A Caveat…
Before we delve into the benefits, let me begin with a caveat. Research on the benefits of testosterone is inconclusive in some areas. You’ll find some research saying, “T gives you ‘x’ benefit,” but other research that says, “No, T actually does the opposite.”
The other problem researchers run into when studying the benefits of testosterone is distinguishing between “cause” and “effect.” Is it T that’s providing all these great health benefits or does simply being healthy give you optimal levels of testosterone? It’s tricky because in some instances the answer is “both.” Testosterone (like all hormones) often plays a part in a “virtuous cycle” that regulates a whole host of processes in our bodies — as you increase T, you get healthier; as you get healthier, your T levels rise. It can also play a part in a “vicious cycle” — as your T levels go down, your health suffers; as your health suffers, your T levels decrease even more.
Below, when a supposed benefit of testosterone is not 100% conclusive, I’ve used the modifier “may” in the opener.
The Benefits of Optimal Testosterone Levels
Testosterone may fight depression. If you’ve been battling the black dog of depression, it may be because of low testosterone levels. Researchers have found  that men suffering from depression typically have deficient testosterone levels. While scientists haven’t been able to figure out whether it’s low testosterone that causes depression or if depression causes low T levels, preliminary research has shown  that some men suffering depression report improvement in mood and other factors of depression after undergoing doctor-directed testosterone treatments.
As someone who’s prone to being an Eeyore, I can report that I definitely felt much more hearty and hopeful during my experiment. Kate also noticed that I was less moody and in better spirits.
Testosterone decreases body fat. Testosterone plays an important role in regulating insulin, glucose, and fat metabolism. As our T levels decrease, our body’s ability to regulate insulin, glucose, and fat metabolism decreases, which in turn causes adipose tissue (i.e. fat) to begin accumulating.  To add insult to injury, that increased adipose tissue may also contribute to further decreasing testosterone levels because it converts testosterone into estrogen. 
This negative feedback loop may explain why obese men typically have below-normal testosterone levels  and higher levels of estrogen . However, research has shown  that by taking steps to increase testosterone levels, you can break the vicious cycle of low T and high body fat and actually create a virtuous cycle of fat loss and increased T levels.
For an in-depth article on the interplay between testosterone and body fat, click here. 
I can report that I saw decreased body fat during my three-month testosterone experiment. I started off with 18% body fat and ended the experiment with 12% body fat. I almost have a six-pack! This is the leanest I’ve ever been in my entire life. The funny thing is, I wasn’t even trying to shed body fat. It just happened. All hail, mighty testosterone!
Testosterone increases muscle mass. We all know about testosterone’s ability to increase muscle mass and strength. It works its muscle-building magic by increasing muscle protein synthesis. 
I definitely enjoyed an increase in muscle mass during my experiment. Despite dropping six percentage points in body fat in three months, my weight stayed about the same; I began the experiment weighing 185 pounds and I ended it weighing the same. The body fat I lost was replaced with muscle. It was fun to see and hear Kate’s reaction when I’d take off my shirt to get into the shower. “Whoa! Your muscles have gotten huge!”
Another benefit of the increased muscle mass was that I got stronger. My bench press, squat, and deadlift all enjoyed significant gains during my experiment. It’s great to be able to bench press 225 pounds again for 5 sets of 5 like I used to in high school, and I’m on track to beat my maxes on the bench and squat that my 18-year-old self set over 12 years ago.
Testosterone may strengthen your heart. Research on testosterone’s relation to heart health is split. Some scientists have found that men with higher testosterone levels have an increased risk of heart disease , while recent studies  have shown that men with below-normal T levels are more at risk for heart problems. The research is still on-going, but many doctors find the evidence compelling that optimal testosterone levels can help prevent cardiovascular disease.
To be clear, it’s not the testosterone hormone itself that strengthens your cardiovascular system, but rather the myriad of health benefits that come from optimal testosterone levels.
Testosterone strengthens bones. You may have thought of osteoporosis as a health problem that only women have to worry about, but men can suffer from this bone-weakening disease too. And low testosterone levels may be to blame. Testosterone has been shown to play an important role in bone health.  It increases bone density by stimulating bone mineralization as well as decreases bone resorption. Elderly men suffering from osteoporosis typically have sub-optimal testosterone levels. If you want to enjoy strong, healthy bones well into old age, take steps to improve your testosterone levels now.
Testosterone increases libido and improves erections. Testosterone is a sex hormone, so it’s not surprising that low libido and erectile dysfunction are two of the first signs of low T that men notice . If you’ve noticed a sharp decrease in your interest in sex, you might have low testosterone.
When I told people that I was doing an experiment to increase my testosterone, the question that people would invariably ask in hushed tones was, “So, did it, you know, improve your sex life?” Honestly, I didn’t see too much change. I had a robust and healthy sex life before the experiment and continued to do so afterwards. I guess I was a bit more randier than usual, but not much. I’d imagine if you had been suffering from low T for a long time and took steps to increase it, you’d likely see improvement in the bedroom department.
Testosterone may decrease your chances of Alzheimer’s Disease. Several studies  have linked low testosterone levels to an increased risk of Alzheimer’s disease. In a 2010 study by the University of Hong Kong, researchers studied 153 Chinese men who were recruited from social centers. They were at least 55 years and older, lived in the community, and didn’t have dementia. Of those men, 47 had mild cognitive impairment — or problems with clear thinking and memory loss.
Within a year, 10 men who were part of the cognitively-impaired group developed probable Alzheimer’s disease. These men also had low testosterone in their body tissues.
That study is not alone. Researchers at the University of Southern California have reported  that increasing testosterone levels in mice with Alzheimer’s actually slows the progression of the disease. This observation has led scientists to hypothesize that maintaining optimal T levels into old age may help prevent Alzheimer’s in humans.
Testosterone may improve cognitive ability. Not only have studies shown that there is a link between testosterone levels and Alzheimer’s , they’ve also shown a link between T levels and overall cognitive ability, particularly in older men. One such study performed by Dutch researchers found a direct linear relationship between T levels and cognitive function, while other studies have found a linear relationship between memory loss and T levels. Because of these correlations, many researchers believe testosterone plays a role in preventing brain tissue decay in elderly men. The hormone’s connection to cognition explains why some of the symptoms of low T in men are memory loss, trouble concentrating, and “fogginess.”
While studies haven’t found a link between increased testosterone levels and cognitive ability in young men, that shouldn’t stop you young bucks from striving to achieve optimal T levels. It’s important to establish testosterone-healthy habits NOW, so you can reap the benefits in old age.
Testosterone may increase competitiveness. Men are known to be a competitive bunch and testosterone is likely responsible for our drive to win. Testosterone is linked with a man’s desire for power and status (Dabbs & Dabbs 2000). Testosterone ramps up before a fight or competition – producing effects on muscle mass and hemoglobin, quickening reactions, improving visual acuity, and increasing your feelings of endurance and indomitability. It also increases your “gameness:” One study  showed that a man’s testosterone level after losing a game predicted whether or not he got back in for another round. Men who experienced a severe drop were less likely to play again, while men who experienced little or no drop in T levels got back into the game. Researchers concluded from this observation that T is one of the factors driving competitiveness in men.
Testosterone increases dominance and the desire for power. The link between testosterone and dominance has been demonstrated in numerous studies . T motivates men to gain and maintain social status. The desire for dominance can be a bad thing if it leads to criminal behavior, but it’s also what fuels the climb for success, motivates men to resist oppression and buck authority, and may even help you with the ladies…
Testosterone may help you woo a woman. In the animal kingdom, higher testosterone levels have long been shown to be associated with a male’s dominance in the competition for mates. But a recent study  has shown this is true for human males as well. When a pair of men were instructed to compete for the affection of an attractive female undergraduate, the men’s assertiveness, ability to control the conversation, and ultimately, their chances of having the woman say she “clicked” with them most, were positively associated with their pre-competition testosterone levels. So there is truth to the idea that men with swagger get the girl, and this self-assuredness may be partly rooted in T.
Testosterone increases the tolerance for risk-taking. Testosterone has a strong link with one’s willingness to take risks. Studies show  that men with low levels of power and status, but high levels of T, are motivated to take risks in order to gain status and power. On the other hand, men with high T, who already have power and status, are more risk-averse, because they want to hold on to what they have.
It has also been found  that college graduates with higher levels of T (men and women alike) are more likely to go into riskier careers. Another study  discovered that among financial traders, a trader’s morning level of testosterone accurately predicted his day’s profitability – higher levels of T mean he’s more likely to take risks that day and score big.
Finally, related to the point about competitiveness above, studies have shown that testosterone levels not only go up before a fight or competition, they increase after each win , and this gives the winner a much higher probability of winning his next round, and the next round after that, even against evenly matched competitors. This is called the “winner-effect ,” and John Coates, author of The Hour Between Dog and Wolf: Risk Taking, Gut Feelings and the Biology of Boom and Bust , explains why it works:
“Life for the winner is more glorious. It enters the next round of competition with already elevated testosterone levels, and this androgenic priming gives it an edge that increases its chances of winning yet again. Through this process an animal can be drawn into a positive-feedback loop, in which victory leads to raised testosterone levels which in turn leads to further victory.”
The potential downside of this positive feedback loop, Coates argues, is that testosterone levels can eventually surge past optimal levels and have the opposite effect – leading to overconfidence and poor decision-making. When this happens to animals, Coates, observed, they “go out in the open, pick too many fights [and] patrol areas that are too large…Risk taking becomes risky behaviour.”
For this reason, after the 2008 financial market meltdown, some commentators  put the blame for the crash on the male-dominated profession, arguing that men take too many risks, and the economy would do better and be more stable if it was run by women. Of course, risk-taking does come with inherent risk, but it has also been responsible for the lion’s share of society’s progress and innovation since the dawn of time. Financial markets would likely not exist – period – without testosterone-driven risk-taking.
Myths about Testosterone
Testosterone results in anti-social behavior. Testosterone gets a bad rap as causing antisocial behavior – bullying, aggression, not getting along with others, taking advantage of others, etc.
However, studies have found that social success among men is actually linked with high testosterone levels. For example, teenage boys who were perceived as socially adept and dominant had higher levels of testosterone than boys that were low on the totem pole . What’s even more interesting is that this same study found that teenage boys who had a history of being anti-social and displaying high physical aggression were found to have lower testosterone levels at age 13 compared with boys with no history of high physical aggression.
Testosterone’s pro-social effect can also be seen in grown men. Swiss researchers found  that men with increased testosterone acted much more fairly in a bargaining game than men with lower T. The results were a surprise to researchers, who thought they’d see more unethical and anti-social behavior among men with higher testosterone.
In a similar study using a bargaining game, researchers found  that aggressive social behavior occurred in men with high testosterone ONLY when there was a perceived unfairness in the bargaining situation. So if there’s a threat of getting bamboozled by someone, a man with high T gets unfriendly.
Testosterone makes you angry. This is probably the most common myth about T. The reality is that there’s no concrete evidence that high testosterone levels cause anger and violent outbursts. In fact, the opposite might be true; low testosterone, not high T, is what causes anger and irritability in men. As discussed above, having low T levels has been linked to depression in men and it just so happens that two of the primary symptoms of depression in men are increased angry outbursts and irritability. So if you’re chronically angry, you might be depressed, and you might be depressed because you have low T. As I mentioned above, I became less moody and irritable during my experiment, which I attribute to the boost in my testosterone levels.
Where did the myth about T and anger come from? It’s likely from people’s association of testosterone with steroid use and “roid rage.” What’s interesting is that the anger and aggressiveness that comes with steroid use is likely due to decreases in natural testosterone production that is a byproduct of artificially juicing. No T = roid rage.
Testosterone causes prostate cancer. Since the 1940s, it was commonly believed in the medical field that high testosterone levels were the cause of prostate cancer in men. Doctors reached this conclusion because two scientists in 1941 noticed that prostate cancer regressed in a patient after they castrated him and his T levels subsequently declined. This conclusion was based on the results from a single patient!
Since then, multiple studies  have found no link between high testosterone levels and increasing your chances of developing prostate cancer. However — and this is a BIG however — if you already have prostate cancer, increased levels of testosterone may exacerbate the problem. It’s best to wait until after you treat your prostate cancer before you begin any T-boosting regimens. Tread carefully and talk with your doctor.
Testosterone Week Series:
The Declining Virility of Men and the Importance of T 
The Benefits of Optimal Testosterone 
A Short Primer on How T is Made 
What’s a “Normal” Testosterone Level and How to Measure Your T 
How I Doubled My Testosterone Levels Naturally and You Can Too 
Any other benefits of testosterone that I forgot? What’s your experience with testosterone and your health? Share with us in the comments!