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Testosterone Boosting

Healthy testosterone levels are critical for men's health, but confusion abounds. "Normal" ranges vary depending on the lab and health practitioner, and levels don't always correspond to symptoms. A few simple steps can help you maintain healthy levels.

Our evidence-based analysis on testosterone boosting features 33 unique references to scientific papers.

Research analysis led by and reviewed by the Examine team.
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Summary of Testosterone Boosting


Testosterone is an androgen, or male sex hormone, though females also need it in lower amounts. In males, low testosterone has been associated with low libido[1] and poor health outcomes, such as the development of metabolic syndrome.[2] In males and females, low testosterone has been associated with depression.[3][4]

Middle-aged[5] and older[6] males see their testosterone levels decrease by 0.4% to 1.6% per year, many of whom had lower-than-average levels even in their 30s.[7] Fortunately, quality sleep, physical activity, weight management, magnesium, zinc, and vitamin D can all help sustain healthy testosterone levels.

Before you even think about taking a supplement for testosterone, you should really learn some basics about this important hormone.

Testosterone is often seen as the holy grail of hormones for males, but it also impacts females. And like the holy grail, it’s shrouded in mystery. If you take the time to understand the concepts laid out here, you’ll be ready for step-by-step recommendations to help support healthy testosterone levels.

A brief history of testosterone

Testosterone was discovered in 1935 when scientists isolated it from bull testes.[8] In fact, the word comes from combining testicle + sterol + ketone.

Athletes quickly discovered its benefits, and in 1972 the Olympics banned the use of testosterone. The Anabolic Steroid Control Act was passed in 1990 and then updated in 2014, making it a felony offense to use testosterone unless prescribed by a physician for medical use in the United States.

A timeline of testosterone

Testosterone can be a barometer for what’s wrong

If you’re feeling crappy in general, doctors look at a set of common things to form a diagnosis. For example, is your thyroid functioning properly? Is your vitamin D level adequate? If you’re male, there’s a decent chance your doctor will look at your testosterone levels as well.

Vitamin D status in male adults

That’s because testosterone plays a central role in wellness and vitality, and almost 40% of men over the age of 45 have low testosterone.[9] In general, hormones, such as testosterone and thyroid hormone, can play an amazing variety of roles in the body, so it’s important to pay attention to them.

Testosterone status in male adults

Indeed, low testosterone is linked to inflammation, weight gain, and worsened cardiovascular health, among many other ailments.[2]

The problem is that low testosterone can mean a number of things: something’s wrong with your body; it could be an age-related decline; or you naturally have lower-than-average testosterone levels. And if something’s wrong with your body, how easy is it to find the culprit — or, more likely, culprits? We’ll get to some answers in a bit, but first, let’s look at what the normal range is for testosterone.

Low testosterone can make you feel lethargic, depressed, and generally lousy. It can be a death knell for gains at the gym. Perhaps even more important, it’s linked to chronic disease. But the devil is in the details: low T can have a variety of causes, not all of which are easy to fix.

The range for testosterone is not standardized

Testosterone levels — both total T and free T[10] — seem to have decreased in American males over the past few decades. But testosterone levels may not tell the whole story of how testosterone is functioning in the body. Your total testosterone can be divided into three categories.[11]

  • Tightly bound testosterone: About two-thirds of the testosterone in your blood is bound to sex hormone binding globulin (SHBG). It is not readily available for use by your body.

  • Loosely bound testosterone: About one-third of the testosterone in your blood is weakly bound to albumin. Once the bond is broken, the testosterone circulates as free testosterone in your body.

  • Free testosterone: A small percentage of the testosterone in your blood (1–4%, as a rule) floats around freely. Your body can readily use it, and the enzyme 5-alpha-reductase can convert it to dihydrotestosterone (DHT), a very potent androgen.

Together, your loosely bound and free testosterone compose your bioavailable testosterone, which has a greater impact on your health than your total testosterone.

When your T levels are tested, the reference range can vary a lot from lab to lab. A recent study showed that the bottom of the range can be 5.55–10.4 nanomoles per liter, or nmol/L (160–300 nanograms per deciliter, or ng/dL), and the top of the range can be 25.17–39.18 nmol/L (726–1,130 ng/dL).[12] So if your levels are measured at 9.71 nmol/L (280 ng/dL), you may or may not be considered as having “low testosterone”.[12]

Assessing testosterone levels
Testosterone is measured as total and free testosterone. Getting measured isn’t the end of the story, though, since the range can vary a ton. So you’ll have to do your homework to figure out if you need to take action.

What causes low testosterone?


Unscrupulous supplement companies want you to believe that as you get older, the only way to prevent plummeting testosterone is with a cocktail of supplements. Decreasing testosterone even has a fancy-sounding name: andropause. Oh no, my androgens have paused. What do I do?!

Here’s what to do: pause, back away from the supplement bottle, and look at what the evidence actually says.

Total testosterone goes down by about 1–2% per year on average,[5] starting sometime in your 30s, and bioavailable testosterone decreases by about 2–3% a year. Those numbers can be pretty misleading though. Men approaching middle age tend to exercise a lot less and eat a lot worse. So nobody really knows what a “natural” decline in testosterone looks like on a population-wide basis.

It’s kind of like saying muscle mass decreases 1–2% a year once you hit middle age. That decrease can have a lot to do with more time spent on work and family and less time spent trying to get ripped.

Age and testosterone

Remember when we mentioned that almost 40% of men over the age of 45 have low T? Well, there’s a wrinkle, and it’s an important one. Only around 10% of men actually have symptoms of low T.[9] So there’s a mismatch: some men with low T have symptoms, while others with low T feel OK or even great. That’s a surefire sign that testosterone isn’t likely the only factor at play.

In fact, if you prescribe testosterone to elderly men with low-normal T levels, their symptoms may not change![13]

Yes, testosterone is very important. And yes, it goes down with age. But some people feel great after boosting their T levels, while others don’t feel any difference.


Resistance training can raise testosterone levels for 15–30 minutes after exercise.[14][15] More important, it can benefit testosterone production in the long run by improving body composition and reducing insulin resistance.[14]

Overtraining is counterproductive. Prolonged endurance exercise especially can cause your testosterone to drop.[16][17] Ensuring adequate recovery time will help you reap the full benefits of physical activity.

Don’t train too much without eating enough or train too little while eating too much. You don’t want to burn yourself out, but you also don’t want to be a sloth.

Effects of exercise and eating on testosterone


This one is big. Things such as alcohol, not enough fat intake, and high blood sugar levels can all negatively impact your testosterone. If you gain weight — fat, not muscle — your testosterone production drops. Fortunately, if you lose weight, your testosterone production can climb back up.[18][19] 

A meta-analysis of 24 randomized controlled trials (RCTs) looked at weight loss as a result of diet or bariatric surgery.[20] 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).

You don’t need to lose huge amounts of weight to see a bump in your testosterone levels either: reducing weight by 5% can increase total testosterone by 2 nmol/L (58 ng/dL).[21]

Dietary factors influencing testosterone

* Only for extremely high intake
** Moderate-to-high consumption can lower T by 7%


To optimize your testosterone, you can’t just supplement your way to high T levels. You also need to sleep well, exercise, and maintain a healthy weight. Quality sleep, physical activity, and weight management synergistically support healthy testosterone levels. If you lack sleep, you’ll find it harder to exercise and easier to gain fat. If you exercise, you’ll find it easier to sleep well and keep a healthy weight. If your weight is in the healthy range, you’ll find it easier to exercise and sleep.

Vicious cycle of staying up late and feeling crappy


There are a lot of pollutants around you that may negatively impact your hormones, deriving from the products you use to the environment you live in. For decades, starting in the 1960s, plastic made with bisphenol A (BPA) was considered the ideal material — light, resilient, and less likely than other plastics to absorb odors and become smelly.

Since then, however, BPA has been shown to interact with estrogen receptors and thus potentially cause a plethora of adverse effects in fetuses, infants, children, and adults (of both sexes).[22]

Eating canned foods (such as canned soup or fruit, or the canned foods going into the dishes you order) can expose you to BPA,[23] as can handling some types of paper store receipts.[24] And while BPA is now seldom used to make reusable plastic bottles, many such bottles now advertised as BPA-free can also release estrogenic chemicals.[25]

Phthalates, a class of chemicals that can be added to plastics, have also been implicated as chemicals of concern which can interfere with testosterone production.[26][27]

As always, exposures won’t necessarily tank your testosterone levels and the effect is dependent on the amount of duration of exposure. But there are safer alternatives that exist, such as glass or metal bottles, and using less plastic is generally a good idea.

How can I normalize my testosterone?

Maintaining a healthy testosterone level is important for many people, and we’ve written a very detailed testosterone guide on the current evidence behind different supplements.

But you should also be thinking about the forest, not just the trees. Why is your T low? What else might be going on?

Testosterone can plummet with inadequate sleep and when you’re super stressed out or working out too much, (due to the effects of cortisol).[16] Many other things can impact T levels, ranging from alcohol use to BPA.[28]

If your body fat is impacting your health, this can lead to a vicious cycle with testosterone levels.

  • Extra fat and worse metabolic health → lower testosterone[29]

  • Lower testosterone → less energy to exercise and feeling crappy, which leads to stress eating

  • Less exercise and worse eating → lower testosterone, and so on and so on

Don’t feel like you have to take prescription testosterone to feel better. For some, this is the only option that works. But for many, a change in habits can help. And for others, testosterone isn’t even to blame. There are a million and one reasons you could be feeling fatigued and have a lower libido than usual!

Here are five actions you can take to help increase and normalize your testosterone levels.

Factors that can help improve your T levels

Do you want evidence-based information on supporting your testosterone levels?

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Frequently Asked Questions and Articles on Testosterone Boosting

Does ashwagandha increase testosterone?
There is a bit of evidence that shows Ashwagandha increases testosterone, but it is not convincing.

Things to Note

Do Not Confuse With

'Steroids' (the vague societal term for illicit drugs)

🔎 Get unbiased information on what supplements to take to boost testosterone

If you want unbiased and expert guidance — based on scientific research — then you need our Supplement Guides.

Each guide breaks down what’s beneficial, what dosage is right for you, when to take each supplement, and more. They also cover any potential side effects, interactions, and more.

Click here to see all 33 references.